WO2023192282A1

WO2023192282A1 - Methods for treating brain glucose hypometabolism

Info

Publication number: WO2023192282A1
Application number: PCT/US2023/016569
Authority: WO
Inventors: Gilbert DI PAOLO; Kathryn M. MONROE; Jung H. SUH; Bettina VAN LENGERICH; Dan Xia
Original assignee: Denali Therapeutics Inc.
Priority date: 2022-03-28
Filing date: 2023-03-28
Publication date: 2023-10-05

Abstract

Certain embodiments provide a method for treating brain glucose hypometabolism in a subject in need thereof, comprising administering to the subject an effective amount of an agonist anti-triggering receptor expressed on myeloid cells 2 (TREM2) antibody.

Description

METHODS FOR TREATING BRAIN GLUCOSE HYPOMETABOLISM

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application Serial No. 63/324,425, filed March 28, 2022. The entire content of the application referenced above is hereby incorporated by reference herein.

BACKGROUND

While neurodegenerative diseases generally have complex etiologies, brain glucose hypometabolism has been shown to be a common feature that links many of these disorders. For example, decreased brain glucose consumption has been reported to play a role in Alzheimer’s disease (AD), Parkinson’s disease, and epilepsy. In particular, brain glucose hypometabolism is an early feature of AD (Jack, et al., Lancet Neurol 12, 207-216 (2013)) and has been associated with more rapid cognitive decline (Ou, Y.N., et al. Alzheimers Res Ther 11, 57 (2019)). Current therapeutics for treating brain glucose hypometabolism are limited. Accordingly, new approaches and therapies are needed.

BRIEF SUMMARY

Certain embodiments provide an agonist anti-TREM2 antibody for use in treating brain glucose hypometabolism in a subject in need thereof.

Certain embodiments provide the use of an agonist anti-TREM2 antibody in the preparation of a medicament for treating brain glucose hypometabolism in a subject in need thereof.

Certain embodiments provide a method for treating a neurodegenerative disease in a subject having brain glucose hypometabolism, the method comprising administering to the subject an effective amount of an agonist anti-TREM2 antibody.

Certain embodiments provide an agonist anti-TREM2 antibody for use in treating a neurodegenerative disease in a subject having brain glucose hypometabolism.

Certain embodiments provide the use of an agonist anti-TREM2 antibody in the preparation of a medicament for treating a neurodegenerative disease in a subject having brain glucose hypometabolism. Certain embodiments provide a method of increasing glucose metabolism, glucose uptake and/or glucose oxidation in a TREM2 expressing cell, comprising contacting the cell with an effective amount of an agonist anti-TREM2 antibody.

Certain embodiments provide an agonist anti-TREM2 antibody for use in increasing glucose metabolism, glucose uptake and/or glucose oxidation in a TREM2 expressing cell.

Certain embodiments provide the use of an agonist anti-TREM2 antibody in the preparation of a medicament for increasing glucose metabolism, glucose uptake and/or glucose oxidation in a TREM2 expressing cell.

Certain embodiments provide a method of selecting a subject having a neurodegenerative disease for treatment with an agonist anti-TREM2 antibody, the method comprising evaluating the subject’s brain glucose metabolism levels and selecting the subject for treatment when the levels are less than a control value.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1A-1B. ATV:TREM2 improved mitochondrial metabolism by promoting glucose oxidation in microglia. Seahorse analysis shows ATV:TREM2 (lOOnM, 3 day treatment) increases maximal microglial respiration via enhanced glucose oxidation. The antibody effect is blocked by a mitochondrial pyruvate carrier (MPC) inhibitor UK5099.

Figures 2A-2D. (Fig. 2A) Representative images of super-resolution microscopy showing iMG stained with TMRE and mitochondrial segmentation into networked and punctate morphologies. (Fig. 2B) Morphometric analysis showing ATV:TREM2 increases the prevalence of networked mitochondria (n=3). Data for Figs. 2A-2B are represented as mean +/- SEM of n independent experiments; unpaired t-test: *p<0.05, **p<0.01, ***p<0.001, and ****p<0.0001. (Fig. 2C) Volcano plots of RNA-seq analysis of microglia isolated from mice dosed with lOmg/kg ATV1SO or ATV:TREM2 for 1, 4, or 7 days. Dots in the upper right quadrant or dots in the upper left quadrant indicate significantly up or down regulated genes, respectively. The x-axis represents log2 fold change in expression compared to vehicle treated mice, and y-axis represents -logio adjusted p value. (Fig. 2D) Relative expression (z-scores) of the topmost up- or downregulated genes at day 1 post dose selected from oxidative phosphorylation and glycolysis pathways.

Figures 3A-3H. ATV:TREM2 increases brain microglial activity and glucose metabolism in an AD model. (Fig. 3A) Coronal and axial slices show cold scaled group average images of TSPO-PET (SUVH) with n=6 per group projected upon a standard MRI Tlw atlas from either 5XFAD; hTREM2 tg; TfR^mu/hu mice (top row) or WT; hTREM2 tg; TfR^mu/hu mice (bottom row) dosed with ATVTSO or ATV:TREM2 (10 mg/kg) on day 1, 4, or 8 post dose. (Figs. 3B, 3C) Quantification of microglial activity measured by in vivo TSPO-PET at day 1, 4 and 8 after ATV1SO or ATV:TREM2 dose in 5XFAD; hTREM2 tg; TfR^mu/hu mice (Fig. 3B) and WT; hTREM2 tg; TfR^mu/humice (Fig. 3C). Scatter plot illustrates individual TSPO-PET (SUVH) values derived from a forebrain VOI. Lines represent linear associations between interval after antibody dosing and TSPO-PET quantification per group and with a 95% confidence interval. (Fig. 3D) Coronal and axial slices show cold scaled group average images of FDG (SUV) with n = 6 per group projected upon a standard MRI Tlw atlas from 5XFAD; hTREM2 tg; TfR^mu/hu mice (top row) or WT; hTREM2 tg; TfR^mu/hu mice (bottom row) dosed with ATVTSO or ATV:TREM2 (10 mg/kg) on day 1, 4, or 8. (Figs. 3E, 3F) Quantification of cortical glucose uptake measured by in vivo FDG-PET at day 1, 4 and 8 after dose of ATVTSO or ATVTREM2 for 5XFAD; hTREM2 tg; TfR^mu/hu mice (Fig. 3E) and WT; hTREM2 tg; TfR^mu/hu mice (Fig. 3F). Scatter plot illustrates individual FDG (SUV) values derived from a forebrain VOI. Lines represent linear associations between interval after antibody dosing and FDG-PET quantification per group with a 95% confidence interval. Statistics were calculated by unpaired t-test at each timepoint: *p<0.05, **p<0.01, ***p<0.001, and ****p<0.0001. (Figs. 3G, 3H) Regional correlation of biomarker alterations (5XFAD; hTREM2 tg; TfR^mu/hu vs. WT; hTREM2 tg; TfR^mu/hu mice) between FBB- PET at 5 months and TSPO PET (SUVH) and FDG-PET (SUV) at the group level.

Figures 4A-4B: ATV:TREM2 increases surface levels of GLUT1 in iPSC microglia. (Fig. 4A) GLUT1 surface levels (Fig. 4A) and GLUT1 total levels (Fig. 4B) in iPSC microglia after treatment with either ATVTSO or ATV:TREM2. Statistics were calculated by unpaired t- test: ***p<0.001.

DETAILED DESCRIPTION

I. INTRODUCTION

Triggering receptor expressed on myeloid cells 2 (TREM2) is a transmembrane receptor that is expressed on the cell surface of microglia, dendritic cells, macrophages, and osteoclasts. Without being bound to a particular theory, it is believed that upon ligand binding, TREM2 forms a signaling complex with a transmembrane adapter protein, DNAX-activating protein 12 (DAP12), which in turn is tyrosine phosphorylated by the protein kinase SRC. It is believed that the activated TREM2/DAP12 signaling complex mediates intracellular signaling by recruiting and phosphorylating kinases such as Syk kinase. TREM2/DAP12 signaling modulates activities such as phagocytosis, cell growth and survival, pro-inflammatory cytokine secretion, and the migration of cells such as microglia and macrophages. TREM2 undergoes regulated intramembrane proteolysis, in which the membrane-associated full-length TREM2 is cleaved by the metalloprotease ADAMI 0 into a sTREM2 portion that is shed from the cell and a membrane- retained C-terminal fragment that is further degraded by a gamma-secretase.

Brain glucose hypometabolism is a common feature of many neurodegenerative disorders, including e.g., Alzheimer’s disease (Jack, et al., Lancet Neurol 12, 207-216 (2013)), Parkinson’s disease and epilepsy. Recent findings suggest microglial activation state can contribute to glucose metabolism in the brain detected by 2-deoxy-2[¹⁸F]fluoro-d-glucose (FDG)-PET imaging (Xiang, X., et al., Sci Transl Med 13, eabe5640 (2021)). TREM2 loss of function (LOF) mouse models have been reported to display hypometabolism (Kleinberger, G., et al., EMBO J 36, 1837-1853 (2017); Gotzl, J.K., et al., EMBO Mol Med 11 (2019)); however, the direct and/or indirect roles that TREM2 plays in relation to this deficiency have not been clear. As described herein, activation of TREM2 using an agonist anti-TREM2 antibody, as exemplified by ATV:TREM2, has been shown for the first time to increase brain glucose metabolism in an AD mouse model (see, Example 1). Accordingly, certain embodiments disclosed herein provide a method for treating brain glucose hypometabolism in a subject in need thereof (e.g., a human), comprising administering to the subject an effective amount of an agonist anti-TREM2 antibody.

II. DEFINITIONS

As used herein, the singular forms “a,” “an” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to “an antibody” optionally includes a combination of two or more such molecules, and the like.

As used herein, the terms “about” and “approximately,” when used to modify an amount specified in a numeric value or range, indicate that the numeric value as well as reasonable deviations from the value known to the skilled person in the art, for example ± 20%, ± 10%, or ± 5%, are within the intended meaning of the recited value.

As used herein, the term “TREM2 protein” refers to a triggering receptor expressed on myeloid cells 2 protein that is encoded by the gene TREM2. As used herein, a “TREM2 protein” refers to a native (i.e., wild-type) TREM2 protein of any vertebrate, such as but not limited to humans, non-human primates (e.g., cynomolgus monkey), rodents (e.g., mice, rat), and other mammals. In some embodiments, a TREM2 protein is a human TREM2 protein having the sequence identified in UniprotKB accession number Q9NZC2 (SEQ ID NO: 1).

As used herein, the term “anti-TREM2 antibody” refers to an antibody that specifically binds to a TREM2 protein (e.g., human TREM2). As used herein, the term “agonist anti-TREM2 antibody” refers to an antibody that can specifically bind to and activate a TREM2 protein or increase at least one biological activity of TREM2.

As used herein, the term “antibody” refers to a protein with an immunoglobulin fold that specifically binds to an antigen via its variable regions. The term encompasses intact polyclonal antibodies, intact monoclonal antibodies, single chain antibodies, multispecific antibodies such as bispecific antibodies, monospecific antibodies, monovalent antibodies, chimeric antibodies, humanized antibodies, and human antibodies. The term “antibody,” as used herein, also includes antibody fragments that retain binding specificity via its variable regions, including but not limited to Fab, F(ab’)2, Fv, scFv, and bivalent scFv. Antibodies can contain light chains that are classified as either kappa or lambda. Antibodies can contain heavy chains that are classified as gamma, mu, alpha, delta, or epsilon, which in turn define the immunoglobulin classes, IgG, IgM, IgA, IgD and IgE, respectively.

As used herein, the term “anti-TREM2 antigen binding portion” refers to an antigen binding segment or entity that specifically binds to a TREM2 protein (e.g., human TREM2). The terms “antigen-binding portion” and “antigen-binding fragment” are used interchangeably herein and refer to one or more fragments of an antibody that retains the ability to specifically bind to an antigen (e.g., a TREM2 protein) via its variable region. Examples of antigen-binding fragments include, but are not limited to, a Fab fragment (a monovalent fragment consisting of the VL, VH, CL and CHI domains along with at least a partial hinge sequence), F(ab’)2 fragment (a bivalent fragment comprising two Fab fragments linked by a disulfide bridge at the hinge region), single chain Fv (scFv), disulfide-linked Fv (dsFv), complementarity determining regions (CDRs), a VL (light chain variable region), and a VH (heavy chain variable region).

The term “variable region” or “variable domain” refers to a domain in an antibody heavy chain or light chain that is derived from a germline Variable (V) gene, Diversity (D) gene, or Joining (J) gene (and not derived from a Constant (Cp and C6) gene segment), and that gives an antibody its specificity for binding to an antigen. Typically, an antibody variable region comprises four conserved “framework” regions interspersed with three hypervariable “complementarity determining regions.”

The term “complementarity determining region” or “CDR” refers to the three hypervariable regions in each chain that interrupt the four framework regions established by the light and heavy chain variable regions. The CDRs are primarily responsible for antibody binding to an epitope of an antigen. The CDRs of each chain are typically referred to as CDR1, CDR2, and CDR3, numbered sequentially starting from the N-terminus, and are also typically identified by the chain in which the particular CDR is located. Thus, a VH CDR3 or CDR-H3 is located in the variable region of the heavy chain of the antibody in which it is found, whereas a VL CDR1 or CDR-L1 is the CDR1 from the variable region of the light chain of the antibody in which it is found.

The “framework regions” or “FRs” of different light or heavy chains are relatively conserved within a species. The framework region of an antibody, that is the combined framework regions of the constituent light and heavy chains, serves to position and align the CDRs in three- dimensional space. Framework sequences can be obtained from public DNA databases or published references that include germline antibody gene sequences. For example, germline DNA sequences for human heavy and light chain variable region genes can be found in the “VBASE2” germline variable gene sequence database for human and mouse sequences.

The amino acid sequences of the CDRs and framework regions can be determined using various well-known definitions in the art, e.g., Kabat, Chothia, international ImMunoGeneTics database (IMGT), AbM, and observed antigen contacts (“Contact”). In some embodiments, CDRs are determined according to the Contact definition. See, MacCallum el al., J. Mol. Biol., 262:732- 745 (1996). In some embodiments, CDRs are determined by a combination of Kabat, Chothia, and/or Contact CDR definitions.

The term “epitope” refers to the area or region of an antigen to which the CDRs of an antibody specifically binds and can include a few amino acids or portions of a few amino acids, e.g., 5 or 6, or more, e.g., 20 or more amino acids, or portions of those amino acids. For example, where the target is a protein, the epitope can be comprised of consecutive amino acids (e.g., a linear epitope), or amino acids from different parts of the protein that are brought into proximity by protein folding (e.g., a discontinuous or conformational epitope). In some embodiments, the epitope is phosphorylated at one amino acid (e.g., at a serine or threonine residue).

As used herein, the phrase “recognizes an epitope,” as used with reference to an agonist anti-TREM2 antibody, means that the antibody CDRs interact with or specifically bind to the antigen (i.e., the TREM2 protein) at that epitope or a portion of the antigen containing that epitope.

A “monoclonal antibody” refers to antibodies produced by a single clone of cells or a single cell line and consisting of or consisting essentially of antibody molecules that are identical in their primary amino acid sequence.

A “polyclonal antibody” refers to an antibody obtained from a heterogeneous population of antibodies in which different antibodies in the population bind to different epitopes of an antigen. A “chimeric antibody” refers to an antibody molecule in which the constant region, or a portion thereof, is altered, replaced or exchanged so that the antigen-binding site (i.e., variable region, CDR, or portion thereof) is linked to a constant region of a different or altered class, effector function and/or species, or in which the variable region, or a portion thereof, is altered, replaced or exchanged with a variable region having a different or altered antigen specificity (e.g, CDR and framework regions from different species). In some embodiments, a chimeric antibody is a monoclonal antibody comprising a variable region from one source or species (e.g., mouse) and a constant region derived from a second source or species (e.g., human). Methods for producing chimeric antibodies are described in the art.

A “humanized antibody” is a chimeric immunoglobulin derived from a non-human source (e.g., murine) that contains minimal sequences derived from the non-human immunoglobulin outside the CDRs. In general, a humanized antibody will comprise at least one (e.g, two) antigen-binding variable domain(s), in which the CDR regions substantially correspond to those of the non-human immunoglobulin and the framework regions substantially correspond to those of a human immunoglobulin sequence. The humanized antibody can also comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin sequence. Methods of antibody humanization are known in the art.

A “human antibody” or a “fully human antibody” is an antibody having human heavy chain and light chain sequences, typically derived from human germline genes. In some embodiments, the antibody is produced by a human cell, by a non-human animal that utilizes human antibody repertoires (e.g., transgenic mice that are genetically engineered to express human antibody sequences), or by phage display platforms.

The term “specifically binds” refers to a molecule (e.g., an antibody or an antigenbinding portion thereof) that binds to an epitope or target with greater affinity, greater avidity, and/or greater duration to that epitope or target in a sample than it binds to another epitope or nontarget compound (e.g., a structurally different antigen). In some embodiments, an antibody (or an antigen-binding portion thereof) that specifically binds to an epitope or target is an antibody (or an antigen-binding portion thereof) that binds to the epitope or target with at least 5 -fold greater affinity than other epitopes or non-target compounds, e.g., at least 5-fold, 10-fold, 100-fold, 1,000- fold, 10,000-fold, or greater affinity. The term “specific binding,” “specifically binds to,” or “is specific for” a particular epitope or target, as used herein, can be exhibited, for example, by a molecule having an equilibrium dissociation constant KD for the epitope or target to which it binds of, e.g., IO'⁴ M or smaller, e.g., IO'⁵ M, IO'⁶ M, IO'⁷ M, IO'⁸ M, IO'⁹ M, IO'¹⁰ M, IO'¹¹ M, or IO'¹² M. It will be recognized by one of skill that an antibody that specifically binds to a target (e.g, a TREM2 protein) from one species may also specifically bind to orthologs of that target (e.g., the TREM2 protein).

The term “binding affinity” is used herein to refer to the strength of a non-covalent interaction between two molecules, e.g., between an antibody (or an antigen-binding portion thereof) and an antigen. Thus, for example, the term may refer to 1 : 1 interactions between an antibody (or an antigen-binding portion thereof) and an antigen, unless otherwise indicated or clear from context. Binding affinity may be quantified by measuring an equilibrium dissociation constant (KD), which refers to the dissociation rate constant (kd, time'¹) divided by the association rate constant (k_a, time'¹ M'¹). KD can be determined by measurement of the kinetics of complex formation and dissociation, e.g., using Surface Plasmon Resonance (SPR) methods, e.g., a Biacore™ system; kinetic exclusion assays such as KinExA®; and BioLayer interferometry (e.g., using the ForteBio® Octet platform). As used herein, “binding affinity” includes not only formal binding affinities, such as those reflecting 1 : 1 interactions between an antibody (or an antigenbinding portion thereof) and an antigen, but also apparent affinities for which KD values are calculated that may reflect avid binding.

The term “cross-reacts,” as used herein, refers to the ability of an antibody to bind to an antigen other than the antigen against which the antibody was raised. In some embodiments, cross-reactivity refers to the ability of an antibody to bind to an antigen from another species than the antigen against which the antibody was raised. As a non-limiting example, an agonist anti- TREM2 antibody as described herein that is raised against a human TREM2 peptide can exhibit cross-reactivity with a TREM2 peptide or protein from a different species (e.g., monkey or mouse).

A “transferrin receptor” or “TfR” as used herein refers to transferrin receptor protein 1. The human transferrin receptor 1 polypeptide sequence is set forth in SEQ ID NO:62. Transferrin receptor protein 1 sequences from other species are also known (e.g., chimpanzee, accession number XP_003310238.1; rhesus monkey, NP_001244232.1; dog, NP_001003111.1; cattle, NP_001193506.1; mouse, NP_035768.1; rat, NP_073203.1; and chicken, NP_990587.1). The term “transferrin receptor” also encompasses allelic variants of exemplary reference sequences, e.g., human sequences, that are encoded by a gene at a transferrin receptor protein 1 chromosomal locus. Full length transferrin receptor protein includes a short N-terminal intracellular region, a transmembrane region, and a large extracellular domain. The extracellular domain is characterized by three domains: a protease-like domain, a helical domain, and an apical domain. The apical domain sequence of human transferrin receptor 1 is set forth in SEQ ID NO:55. The terms “CH3 domain” and “CH2 domain” as used herein refer to immunoglobulin constant region domain polypeptides. In the context of IgG antibodies, a CH3 domain polypeptide refers to the segment of amino acids from about position 341 to about position 447 as numbered according to the EU numbering scheme, and a CH2 domain polypeptide refers to the segment of amino acids from about position 231 to about position 340 as numbered according to the EU numbering scheme and does not include hinge region sequences. CH2 and CH3 domain polypeptides may also be numbered by the IMGT (ImMunoGeneTics) numbering scheme in which the CH2 domain numbering is 1-110 and the CH3 domain numbering is 1-107, according to the IMGT Scientific chart numbering (IMGT website). CH2 and CH3 domains are part of the Fc region of an immunoglobulin. In the context of IgG antibodies, an Fc region refers to the segment of amino acids from about position 231 to about position 447 as numbered according to the EU numbering scheme. As used herein, the term “Fc region” may also include at least a part of a hinge region of an antibody. An exemplary partial hinge region sequence is set forth in SEQ ID NO:57.

The terms “corresponding to,” “determined with reference to,” or “numbered with reference to” when used in the context of the identification of a given amino acid residue in a polypeptide sequence, refers to the position of the residue of a specified reference sequence when the given amino acid sequence is maximally aligned and compared to the reference sequence. Thus, for example, an amino acid residue in a polypeptide “corresponds to” an amino acid in the region of SEQ ID NO:38 from amino acids 111-217 when the residue aligns with the amino acid in SEQ ID NO:38 when optimally aligned to SEQ ID NO:38. The polypeptide that is aligned to the reference sequence need not be the same length as the reference sequence.

As used herein, the term “Fc polypeptide” refers to the C-terminal region of a naturally occurring immunoglobulin heavy chain polypeptide that is characterized by an Ig fold as a structural domain. An Fc polypeptide contains constant region sequences including at least the CH2 domain and/or the CH3 domain and may contain at least part of the hinge region, but does not contain a variable region.

A “modified Fc polypeptide” refers to an Fc polypeptide that has at least one mutation, e.g., a substitution, deletion or insertion, as compared to a wild-type immunoglobulin heavy chain Fc polypeptide sequence, but retains the overall Ig fold or structure of the native Fc polypeptide.

The term “isolated,” as used with reference to a nucleic acid or protein (e.g., antibody), denotes that the nucleic acid or protein is essentially free of other cellular components with which it is associated in the natural state. Purity and homogeneity are typically determined using analytical chemistry techniques such as electrophoresis (e.g., polyacrylamide gel electrophoresis) or chromatography (e.g., high performance liquid chromatography). In some embodiments, an isolated nucleic acid or protein (e.g., antibody) is at least 85% pure, at least 90% pure, at least 95% pure, or at least 99% pure.

The term “amino acid” refers to naturally occurring and synthetic amino acids, as well as amino acid analogs and amino acid mimetics that function in a manner similar to the naturally occurring amino acids. Naturally occurring amino acids are those encoded by the genetic code, as well as those amino acids that are later modified, e.g., hydroxyproline, y-carboxyglutamate, and O-phosphoserine. Naturally occurring a-amino acids include, without limitation, alanine (Ala), cysteine (Cys), aspartic acid (Asp), glutamic acid (Glu), phenylalanine (Phe), glycine (Gly), histidine (His), isoleucine (He), arginine (Arg), lysine (Lys), leucine (Leu), methionine (Met), asparagine (Asn), proline (Pro), glutamine (Gin), serine (Ser), threonine (Thr), valine (Vai), tryptophan (Trp), tyrosine (Tyr), and combinations thereof. Stereoisomers of a naturally occurring a-amino acids include, without limitation, D-alanine (D-Ala), D-cysteine (D-Cys), D-aspartic acid (D-Asp), D-glutamic acid (D-Glu), D-phenylalanine (D-Phe), D-histidine (D-His), D-isoleucine (D-Ile), D-arginine (D-Arg), D-lysine (D-Lys), D-leucine (D-Leu), D-methionine (D-Met), D- asparagine (D-Asn), D-proline (D-Pro), D-glutamine (D-Gln), D-serine (D-Ser), D-threonine (D- Thr), D-valine (D-Val), D-tryptophan (D-Trp), D-tyrosine (D-Tyr), and combinations thereof. “Amino acid analogs” refer to compounds that have the same basic chemical structure as a naturally occurring amino acid, i.e., an a carbon that is bound to a hydrogen, a carboxyl group, an amino group, and an R group, e.g., homoserine, norleucine, methionine sulfoxide, methionine methyl sulfonium. Such analogs have modified R groups (e.g., norleucine) or modified peptide backbones, but retain the same basic chemical structure as a naturally occurring amino acid. “Amino acid mimetics” refers to chemical compounds that have a structure that is different from the general chemical structure of an amino acid, but that functions in a manner similar to a naturally occurring amino acid. Amino acids may be referred to herein by either their commonly known three letter symbols or by the one-letter symbols recommended by the IUPAC-IUB Biochemical Nomenclature Commission.

The terms “polypeptide” and “peptide” are used interchangeably herein to refer to a polymer of amino acid residues in a single chain. The terms apply to amino acid polymers in which one or more amino acid residue is an artificial chemical mimetic of a corresponding naturally occurring amino acid, as well as to naturally occurring amino acid polymers and non- naturally occurring amino acid polymers. Amino acid polymers may comprise entirely L-amino acids, entirely D-amino acids, or a mixture of L and D amino acids. The term “protein” as used herein refers to either a polypeptide or a dimer (i.e., two) or multimer (i.e., three or more) of single chain polypeptides. The single chain polypeptides of a protein may be joined by a covalent bond, e.g., a disulfide bond, or non-covalent interactions.

The terms “polynucleotide” and “nucleic acid” interchangeably refer to chains of nucleotides of any length, and include DNA and RNA. The nucleotides can be deoxyribonucleotides, ribonucleotides, modified nucleotides or bases, and/or their analogs, or any substrate that can be incorporated into a chain by DNA or RNA polymerase. A polynucleotide may comprise modified nucleotides, such as methylated nucleotides and their analogs. Examples of polynucleotides contemplated herein include single- and double-stranded DNA, single- and double-stranded RNA, and hybrid molecules having mixtures of single- and double-stranded DNA and RNA.

The terms “conservative substitution” and “conservative mutation” refer to an alteration that results in the substitution of an amino acid with another amino acid that can be categorized as having a similar feature. Examples of categories of conservative amino acid groups defined in this manner can include: a “charged/polar group” including Glu (Glutamic acid or E), Asp (Aspartic acid or D), Asn (Asparagine or N), Gin (Glutamine or Q), Lys (Lysine or K), Arg (Arginine or R), and His (Histidine or H); an “aromatic group” including Phe (Phenylalanine or F), Tyr (Tyrosine or Y), Trp (Tryptophan or W), and (Histidine or H); and an “aliphatic group” including Gly (Glycine or G), Ala (Alanine or A), Vai (Valine or V), Leu (Leucine or L), He (Isoleucine or I), Met (Methionine or M), Ser (Serine or S), Thr (Threonine or T), and Cys (Cysteine or C). Within each group, subgroups can also be identified. For example, the group of charged or polar amino acids can be sub-divided into sub-groups including: a “positively-charged sub-group” comprising Lys, Arg and His; a “negatively-charged sub-group” comprising Glu and Asp; and a “polar sub-group” comprising Asn and Gin. In another example, the aromatic or cyclic group can be sub-divided into sub-groups including: a “nitrogen ring sub-group” comprising Pro, His and Trp; and a “phenyl sub-group” comprising Phe and Tyr. In another further example, the aliphatic group can be sub-divided into sub-groups, e.g., an “aliphatic non-polar sub-group” comprising Vai, Leu, Gly, and Ala; and an “aliphatic slightly-polar sub-group” comprising Met, Ser, Thr, and Cys. Examples of categories of conservative mutations include amino acid substitutions of amino acids within the sub-groups above, such as, but not limited to: Lys for Arg or vice versa, such that a positive charge can be maintained; Glu for Asp or vice versa, such that a negative charge can be maintained; Ser for Thr or vice versa, such that a free -OH can be maintained; and Gin for Asn or vice versa, such that a free -NH2 can be maintained. In some embodiments, hydrophobic amino acids are substituted for naturally occurring hydrophobic amino acid, e.g., in the active site, to preserve hydrophobicity.

The terms “identical” or percent “identity,” in the context of two or more polypeptide sequences, refer to two or more sequences or subsequences that are the same or have a specified percentage of amino acid residues, e.g., at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% or greater, that are identical over a specified region when compared and aligned for maximum correspondence over a comparison window, or designated region as measured using a sequence comparison algorithm or by manual alignment and visual inspection.

For sequence comparison of polypeptides, typically one amino acid sequence acts as a reference sequence, to which a candidate sequence is compared. Alignment can be performed using various methods available to one of skill in the art, e.g., visual alignment or using publicly available software using known algorithms to achieve maximal alignment. Such programs include the BLAST programs, ALIGN, ALIGN-2 (Genentech, South San Francisco, Calif.) or Megalign (DNASTAR). The parameters employed for an alignment to achieve maximal alignment can be determined by one of skill in the art. For sequence comparison of polypeptide sequences for purposes of this application, the BLASTP algorithm standard protein BLAST for aligning two proteins sequence with the default parameters is used.

The terms “subject,” “individual,” and “patient,” as used interchangeably herein, refer to a mammal, including but not limited to humans, non-human primates, rodents (e.g., rats, mice, and guinea pigs), rabbits, cows, pigs, horses, and other mammalian species. In one embodiment, the subject, individual, or patient is a human.

The terms “treating,” “treatment,” and the like are used herein to generally mean obtaining a desired pharmacologic and/or physiologic effect. “Treating” or “treatment” may refer to any indicia of success in the treatment or amelioration of a neurodegenerative disease (e.g., Alzheimer’s disease or another neurodegenerative disease described herein), including any objective or subjective parameter such as abatement, remission, improvement in patient survival, increase in survival time or rate, diminishing of symptoms or making the disease more tolerable to the patient, slowing in the rate of degeneration or decline, or improving a patient’s physical or mental well-being. The treatment or amelioration of symptoms can be based on objective or subjective parameters. The effect of treatment can be compared to an individual or pool of individuals not receiving the treatment, or to the same patient prior to treatment or at a different time during treatment. As used herein, the term “prone to developing” refers to a subject that is at an increased risk of developing the particular disease or condition (e.g., due to a genetic risk factor, such as a TREM2 mutation; due to a lifestyle choice; or due condition resulting from a combination of genetic and lifestyle factors).

The term “pharmaceutically acceptable excipient” refers to a non-active pharmaceutical ingredient that is biologically or pharmacologically compatible for use in humans or animals, such as, but not limited to a buffer, carrier, or preservative.

As used herein, a “therapeutic amount” or “therapeutically effective amount” of an agent (e.g., an antibody as described herein) is an amount of the agent that treats, alleviates, abates, or reduces the severity of symptoms of a disease in a subject. A “therapeutic amount” of an agent (e.g., an antibody as described herein) may improve patient survival, increase survival time or rate, diminish symptoms, make an injury, disease, or condition (e.g., a neurodegenerative disease) more tolerable, slow the rate of degeneration or decline, or improve a patient’s physical or mental well-being.

The term “administer” refers to a method of delivering agents, compounds, or compositions to the desired site of biological action. These methods include, but are not limited to, topical delivery, parenteral delivery, intravenous delivery, intradermal delivery, intramuscular delivery, intrathecal delivery, colonic delivery, rectal delivery, or intraperitoneal delivery. In one embodiment, an antibody as described herein is administered intravenously.

The term “control” or “control value” refers to a reference value or baseline value. Appropriate controls can be determined by one skilled in the art. In some instances, control values can be determined relative to a baseline within the same subject or experiment, e.g., a measurement of glucose metabolism taken prior to treatment with an agonist anti-TREM2 antibody can be a control value for a post-treatment measurement of glucose metabolism in the same subject. In other instances, the control value can be determined relative to a control subject (e.g., a healthy control or a disease control) or an average value in a population of control subjects (e.g., healthy controls or disease controls, e.g., a population of 10, 20, 50, 100, 200, 500, 1000 control subjects or more), e.g., a measurement of a subject’s glucose metabolism either at baseline or after treatment can be compared to a healthy control value.

III. METHODS FOR THE TREATMENT OF BRAIN GLUCOSE HYPOMETABOLISM AND DISEASES AND DISORDERS ASSOCIATED WITH THIS CONDITION

As described herein, an agonist anti-TREM2 antibody was shown to promote glucose oxidation in microglia and to increase brain glucose metabolism in an Alzheimer’s disease mouse model (see, Example 1). Brain glucose hypometabolism is not only associated with Alzheimer’s disease but is also a common feature of many other neurodegenerative disorders, including, e.g., Parkinson’s disease and epilepsy. Accordingly, as described herein, an agonist anti-TREM2 antibody may be used to increase glucose metabolism in microglia or other cell types expressing TREM2, as well as to treat related diseases and disorders.

Thus, certain embodiments provide a method of increasing glucose metabolism, glucose uptake and/or glucose oxidation in a TREM2 expressing cell, the method comprising contacting the cell with an effective amount of an agonist anti-TREM2 antibody.

In certain embodiments, the cell is a microglial cell (e.g., a human microglial cell). In certain embodiments, the cell is a human iPSC-derived microglial (iMG) cell. In certain embodiments, the cell has reduced TREM2 activity. In other embodiments, the cell has normal TREM2 activity.

In certain embodiments, glucose metabolism in the cell is increased. In certain embodiments, glucose metabolism in the cell is increased by at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or more as compared to a control value (e.g., as compared to levels in the cell prior to contact with the antibody).

In certain embodiments, glucose uptake in the cell is increased. In certain embodiments, glucose uptake in the cell is increased by at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or more as compared to a control value (e.g., as compared to levels in the cell prior to contact with the antibody). In certain embodiments, expression levels of glucose transporter type 1 (GLUT1) protein on the surface of the cell are increased. In certain embodiments, expression levels of GLUT1 on the surface of the cell are increased by at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or more as compared to a control value (e.g., as compared to surface expression levels prior to contact with the antibody).

In certain embodiments, glucose oxidation in the cell is increased. In certain embodiments, glucose oxidation in the cell is increased by at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or more as compared to a control value (e.g., as compared to levels in the cell prior to contact with the antibody).

In certain embodiments, the cell is contacted in vitro.

In certain other embodiments, the cell is present in a subject and is contacted in vivo i.e., via administration of the antibody to the subject). Accordingly, certain embodiments also provide methods of increasing glucose metabolism, glucose uptake and/or glucose oxidation in subject in need thereof, comprising administering to the subject an effective amount of an agonist anti- TREM2 antibody. In some embodiments, the method comprises administering to the subject a pharmaceutical composition comprising an agonist anti-TREM2 antibody.

Assays for measuring glucose metabolism, glucose uptake and glucose oxidation are known in the art and described herein. For example, glucose metabolism and glucose uptake may be evaluated using 2-deoxy-2[¹⁸F]fluoro-d-glucose (FDG)-PET imaging in vivo. Glucose oxidation levels may also be measured using assays known in the art, such using a Seahorse assay. In some embodiments, the assay is performed on a sample comprising cells that endogenously express TREM2, such as human macrophages or microglia. In some embodiments, the assay is performed on a sample comprising cells that have been engineered to express TREM2.

Provided herein is also a method for treating brain glucose hypometabolism in a subject in need thereof (e.g., a human), comprising administering to the subject an effective amount of an agonist anti-TREM2 antibody. In some embodiments, the method comprises administering to the subject a pharmaceutical composition comprising an agonist anti-TREM2 antibody.

As used herein, the term “brain glucose hypometabolism” refers to a condition wherein a subject has decreased brain glucose consumption as compared to a control (e.g., as compared to the consumption level in a healthy control subject(s) or subject that does not have brain glucose hypometabolism or a disease associated with this condition). In addition to reduced metabolism of glucose, this condition may also involve reduced glucose uptake by brain cells (e.g., microglial or neurons) as compared to a control value. Brain glucose metabolism can be measured using an assay known in the art or described herein. For example, glucose uptake in the brain can be detected by in vivo 2-deoxy-2[¹⁸F]fluoro-d-glucose (FDG)-PET imaging (see, e.g., Xiang, X., et al., Sci Transl Med 13, eabe5640 (2021); Example 1).

As noted herein, brain glucose hypometabolism is a condition that has been associated with a number of neurodegenerative diseases and disorders. Therefore, in certain embodiments, “a subject in need thereof’ may be a subject that has a neurodegenerative disease or that is prone to developing a neurodegenerative disease (e.g., a neurodegenerative disease described herein).

Accordingly, certain embodiments also provide a method for treating a neurodegenerative disease in a subject having brain glucose hypometabolism, the method comprising administering to the subject an effective amount of an agonist anti-TREM2 antibody. In certain embodiments, the subject has been diagnosed with brain glucose hypometabolism prior to treatment (e.g., the subject has been selected for treatment based on their diagnosis).

In certain embodiments, administration of the agonist anti-TREM2 antibody increases brain glucose metabolism in the subject by, e g., at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or more as compared a control value (e.g., as compared to metabolism levels in the subject prior to administration). In certain embodiments, glucose metabolism is increased in cells that express TREM2. In certain embodiments, glucose metabolism is increased in the subject’s microglial cells. Thus, in certain embodiments, administration of the agonist anti-TREM2 antibody increases microglial glucose metabolism in the subject by, e.g., at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or more as compared a control value (e.g., as compared to metabolism levels in the subject prior to administration).

In certain embodiments, administration of the agonist anti-TREM2 antibody increases glucose uptake by a brain cell(s) in the subject by, e.g., at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or more as compared a control value (e.g., as compared to glucose uptake levels in the subject prior to administration). In certain embodiments, glucose uptake is increased in cells that express TREM2. In certain embodiments, glucose uptake is increased in the subject’s microglial cells. In certain embodiments, administration of the agonist anti-TREM2 antibody increases GLUT1 expression levels on the surface of a brain cell(s) in the subject by, e.g., at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or more as compared a control value (e.g., as compared to GLUT1 cell surface expression levels in the subject prior to administration). In certain embodiments, GLUT1 cell surface expression levels are increased in cells that express TREM2. In certain embodiments, GLUT! cell surface expression levels are increased in the subject’s microglial cells.

In certain embodiments, administration of the agonist anti-TREM2 antibody increases glucose oxidation in a brain cell(s) in the subject by, e.g., at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or more as compared a control value (e.g., as compared to glucose oxidation levels in the subject prior to administration). In certain embodiments, glucose oxidation is increased in cells that express TREM2. In certain embodiments, glucose oxidation is increased in the subject’s microglial cells.

Glucose metabolism, glucose uptake, and/or glucose oxidation levels may be measured using an assay known in the art or described herein (e.g., an in vivo assay, such as PET imaging).

In certain embodiments, the neurodegenerative disease is selected from the group consisting of Alzheimer’s disease, primary age-related tauopathy, progressive supranuclear palsy (PSP), frontotemporal dementia, frontotemporal dementia with parkinsonism linked to chromosome 17, argyrophilic grain dementia, amyotrophic lateral sclerosis, amyotrophic lateral sclerosis/parkinsonism-dementia complex of Guam (ALS-PDC), corticobasal degeneration, chronic traumatic encephalopathy, Creutzfeldt-Jakob disease, dementia pugilistica, diffuse neurofibrillary tangles with calcification, Down’s syndrome, familial British dementia, familial Danish dementia, Gerstmann-Straussler-Scheinker disease, globular glial tauopathy, Guadeloupean parkinsonism with dementia, Guadelopean PSP, Hallevorden-Spatz disease, hereditary diffuse leukoencephalopathy with spheroids (HDLS), Huntington’s disease, inclusionbody myositis, multiple system atrophy, myotonic dystrophy, Nasu-Hakola disease, neurofibrillary tangle-predominant dementia, Niemann-Pick disease type C, pallido-ponto-nigral degeneration, Parkinson’s disease, Pick’s disease, postencephalitic parkinsonism, prion protein cerebral amyloid angiopathy, progressive subcortical gliosis, subacute sclerosing panencephalitis, adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP), epilepsy, and tangle only dementia. In some embodiments, the neurodegenerative disease is Alzheimer’s disease. In some embodiments, the neurodegenerative disease is Nasu-Hakola disease. In some embodiments, the neurodegenerative disease is frontotemporal dementia. In some embodiments, the neurodegenerative disease is Parkinson’s disease. In some embodiments, the neurodegenerative disease is ALSP.

In certain embodiments, the neurodegenerative disease is further characterized by reduced TREM2 activity (e.g., reduced activity caused by a mutation in TREM2). Thus, in certain embodiments, the subject treated using a method described herein has, or has been determined to have, reduced TREM2 activity. As used herein the term “reduced TREM2 activity” refers to a cell, or a subject comprising such cells, that has reduced TREM2 function as compared to a control cell/subject (e.g., a corresponding cell from a healthy subject). In certain embodiments, the reduced levels of functional protein may result from reduced expression of TREM2 (e.g., via inhibition of transcription, inhibition of RNA maturation, inhibition of RNA translation, altered post-translational modifications, or increased degradation of the RNA or protein) or reduced cell surface levels of TREM2 protein. In certain embodiments, the reduced levels of functional TREM2 are caused by loss or partial loss of function genetic mutations in the TREM2 gene (e.g., R47H, R62H, H157Y, Q33X, T66M or Y38C). In certain embodiments, the reduced levels of functional TREM2 are caused by reduced TREM2 protein levels. In certain embodiments, the reduced levels of functional TREM2 are caused by increased cleavage of the receptor by a disintegrin and metalloproteinase (ADAM) proteases (e.g., ADAM10 and ADAM17), which results in the release of soluble TREM2 (sTREM2) into the extracellular environment. In certain embodiments, the reduced TREM2 activity comprises reduced signaling.

The presence of reduced TREM2 activity in a cell/subject can be established by evaluating a sample (e.g., a sample comprising one or more cells) using an assay described herein or known in the art. For example, the assay may evaluate RNA or protein expression levels, cell surface TREM2 protein levels or may examine TREM2 activity (e.g., signaling) (e.g., as compared to a control). In other embodiments, the assay may measure the levels of sTREM2 (e.g., as compared to a control). Other functional measures of TREM2 activity, such as reduced pSyk activity or class I PI 3 -kinase activity as compared to control cells, can also be used be to identify cells or subjects that have reduced TREM2 activity.

Thus, in certain embodiments, the subject has, or is prone to developing, a neurodegenerative disease that is characterized by a mutation in TREM2. In some embodiments, the neurodegenerative disease that is characterized by a mutation in TREM2 is Alzheimer’s disease, e.g., Alzheimer’s disease that is characterized by a R47H mutation in TREM2.

In certain other embodiments, a subject treated using a method described herein has, or has been determined to have, normal TREM2 activity (e.g., as compared to a healthy control subject).

In certain embodiments, the subject has plaque deposits of beta-amyloid.

In some embodiments, the subject to be treated is a human, e.g., a human adult or a human child.

Certain embodiments also provide a method of selecting a subject having a neurodegenerative disease for treatment with an agonist anti-TREM2 antibody, the method comprising evaluating the subject’s brain glucose metabolism levels, and selecting the subject for treatment when the levels are less than a control value (e.g., less than the levels in a healthy subject or a subject that does not have brain glucose hypometabolism). Certain embodiments also provide a method of selecting a subject (e.g., having a neurodegenerative disease) for treatment with an agonist anti-TREM2 antibody, the method comprising identifying a subject that has brain glucose hypometabolism and selecting the identified patient for treatment with the agonist anti-TREM2 antibody. In certain embodiments, such a method further comprises administering an agonist anti- TREM2 antibody to the subject. In certain embodiments, the subject has a neurodegenerative disorder as described herein. In certain embodiments, the subject has Alzheimer’s disease. In certain embodiments, the subject has Alzheimer’s disease and has plaque deposits of betaamyloid.

Certain embodiments provide a method of selecting a treatment for a subject identified as having brain glucose hypometabolism, the method comprising selecting an agonist anti-TREM2 antibody for the subj ect identified as having brain glucose hypometabolism. Certain embodiments also provide a method of selecting a treatment for a subject, the method comprising identifying the subject has having brain glucose hypometabolism and selecting an agonist anti-TREM2 antibody for the identified subject. Certain embodiments provide a method of treating a subject comprising evaluating the subject’s brain glucose metabolism levels and administering an agonist anti-TREM2 antibody to the subject when the levels are less than a control value (e.g., less than the levels in a healthy subject or a subject that does not have brain glucose hypometabolism).

Certain embodiments provide a method of monitoring the treatment of a subject having brain glucose hypometabolism comprising evaluating the subject’s brain glucose metabolism levels after the subject has been administered an agonist anti-TREM2 agonist, and optionally, further administering an additional dose of an agonist anti-TREM2 antibody to the subject when the levels are less than a control value (e.g., less than the levels in a healthy subject or a subject that does not have brain glucose hypometabolism).

IV. AGONIST ANTI-TREM2 ANTIBODIES

As described herein, in certain embodiments, an effective amount of an agonist anti- TREM2 antibody may be administered to a subject in need thereof to treat brain glucose hypometabolism or a disease or condition associated with brain glucose hypometabolism, such as a disease described herein (e.g., Alzheimer’s disease).

Certain anti-TREM2 antibodies (e.g., agonist anti-TREM2 antibodies) are known in the art and may be used in a method described herein. For example, anti-TREM2 antibodies are described in, e.g., US Patent No. 11,186,636 and PCT Publication Nos. WO2021/113655, WO2021/146256, W02020/172457, W02020/172450, WO2019/055841, WO2019/118513, WO20 19/028292, WO2018/195506, WO2017/062672, WO2017/058866, and W02016/023019.

Additionally, certain examples of agonist anti-TREM2 antibodies and their associated sequences are described below and in Table 2. For example, in some embodiments, an agonist anti-TREM2 antibody for use in a method described herein may comprise one or more complementarity determining region (CDR), heavy chain variable region, and/or light chain variable region sequences as disclosed herein. In some embodiments, the agonist anti-TREM2 antibody comprises Fc polypeptides that comprise one or more modifications as described herein.

In one embodiment, the agonist anti-TREM2 antibody specifically binds to TREM2 and increases its activity. In some embodiments, the antibody specifically binds to a human TREM2 protein. In some embodiments, the antibody is selective for TREM2 over other TREM-like receptors (e.g., TREM1). The ability of an antibody to bind to and activate TREM2 may be determined by certain in vitro or in vivo assays known in the art or described herein, such as binding assays or activity assays. In certain embodiments, the agonist anti-TREM2 antibody is a full-length antibody (for example, an IgGl or IgG4 antibody). In certain embodiments, a fragment of an agonist anti- TREM2 antibody is used in the methods disclosed herein and comprises only an antigen-binding portion (for example, a F(ab')2 fragment). In certain embodiments, the agonist anti-TREM2 antibody is a monoclonal antibody. In certain embodiments, the agonist anti-TREM2 antibody is an isolated recombinant monoclonal antibody that binds specifically to TREM2. In some embodiments, the anti-TREM2 antibody is a chimeric antibody. In some embodiments, the anti- TREM2 antibody is a humanized and/or affinity matured antibody.

In some embodiments, an agonist anti-TREM2 antibody for use in a method described herein may comprise a heavy chain sequence, or a portion thereof, and/or a light chain sequence, or a portion thereof, that is derived from an agonist anti-TREM2 antibody described herein (e.g., Clone CL0020306, Clone CL0020188, Clone CL0020307, Clone A, Clone B, Clone C or Clone D). The CDR, heavy chain variable region, and light chain variable region amino acid sequences of these clones are set forth in Table 2.

Clones CL0020188, CL0020306, CL0020307, and variants of CL0020188

In some embodiments, an agonist anti-TREM2 antibody comprises one or more CDRs selected from the group consisting of:

(a) a heavy chain CDR1 (CDR-H1) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of any one of SEQ ID NOS:4 and 12, or having up to two amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOS:4 and 12;

(b) a heavy chain CDR2 (CDR-H2) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of any one of SEQ ID NOS:5, 13, and 25, or having up to two amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOS:5, 13, and 25;

(c) a heavy chain CDR3 (CDR-H3) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of any one of SEQ ID NOS:6, 14, and 17, or having up to two amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOS:6, 14, and 17;

(d) a light chain CDR1 (CDR-L1) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of any one of SEQ ID NOS:7 and 23, or having up to two amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOS:7 and 23; (e) a light chain CDR2 (CDR-L2) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of SEQ ID NO: 8, or having up to two amino acid substitutions relative to the amino acid sequence of SEQ ID NO:8; and

(f) a light chain CDR3 (CDR-L3) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of any one of SEQ ID NOS:9 and 18, or having up to two amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOS:9 and 18.

In some embodiments, an agonist anti-TREM2 antibody comprises two, three, four, five, or all six of (a)-(f). In some embodiments, an agonist anti-TREM2 antibody comprises the CDR- H1 of (a), the CDR-H2 of (b), and the CDR-H3 of (c). In some embodiments, an agonist anti- TREM2 antibody comprises the CDR-L1 of (d), the CDR-L2 of (e), and the CDR-L3 of (f). In some embodiments, a CDR having up to two amino acid substitutions has one amino acid substitution relative to the reference sequence. In some embodiments, a CDR having up to two amino acid substitutions has two amino acid substitutions relative to the reference sequence. In some embodiments, the up to two amino acid substitutions are conservative substitutions.

(a) a CDR-H1 sequence comprising the amino acid sequence of any one of SEQ ID NOS:4 and 12;

(b) a CDR-H2 sequence comprising the amino acid sequence of any one of SEQ ID NOS:5, 13, and 25;

(c) a CDR-H3 sequence comprising the amino acid sequence of any one of SEQ ID NOS:6, 14, and 17;

(d) a CDR-L1 sequence comprising the amino acid sequence of any one of SEQ ID NOS:7 and 23;

(e) a CDR-L2 sequence comprising the amino acid sequence of SEQ ID NO:8; and

(f) a CDR-L3 sequence comprising the amino acid sequence of any one of SEQ ID NOS:9 and 18.

In some embodiments, an agonist anti-TREM2 antibody comprises two, three, four, five, or all six of (a)-(f). In some embodiments, an agonist anti-TREM2 antibody comprises the CDR- H1 of (a), the CDR-H2 of (b), and the CDR-H3 of (c). In some embodiments, an agonist anti- TREM2 antibody comprises the CDR-L1 of (d), the CDR-L2 of (e), and the CDR-L3 of (f). In some embodiments, an agonist anti-TREM2 antibody comprises:

(a) a CDR-H1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:5, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 17, a CDR-L1 comprising the amino acid sequence of SEQ ID NO:7, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 18; or

(b) a CDR-H1 comprising the amino acid sequence of SEQ ID NON, a CDR- H2 comprising the amino acid sequence of SEQ ID NO:5, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 17, a CDR-L1 comprising the amino acid sequence of SEQ ID NO:23, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 18; or

(c) a CDR-H1 comprising the amino acid sequence of SEQ ID NON, a CDR- H2 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 17, a CDR-L1 comprising the amino acid sequence of SEQ ID NO:7, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 18; or

(d) a CDR-H1 comprising the amino acid sequence of SEQ ID NON, a CDR- H2 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 17, a CDR-L1 comprising the amino acid sequence of SEQ ID NO:23, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 18; or

(e) a CDR-H1 comprising the amino acid sequence of SEQ ID NON, a CDR- H2 comprising the amino acid sequence of SEQ ID NO:5, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 6, a CDR-L1 comprising the amino acid sequence of SEQ ID NO: 7, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:9; or

(f) a CDR-H1 comprising the amino acid sequence of SEQ ID NO: 12, a CDR- H2 comprising the amino acid sequence of SEQ ID NO: 13, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 14, a CDR-L1 comprising the amino acid sequence of SEQ ID NO:7, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:9; or

(g) a CDR-H1 comprising the amino acid sequence of SEQ ID NON, a CDR- H2 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 17, a CDR-L1 comprising the amino acid sequence of SEQ ID NO:7, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:9.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to any one of SEQ ID NOS:2, 10, 15, 19, 21, 24, and 26. In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising the amino acid sequence of any one of SEQ ID NOS:2, 10, 15, 19, 21, 24, and 26.

In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to any one of SEQ ID NOS:3, 11, 16, 20, 22, and 27. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising the amino acid sequence of any one of SEQ ID NOS:3, 11, 16, 20, 22, and 27.

In some embodiments, an agonist anti-TREM2 antibody comprises: a heavy chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to any one of SEQ ID NOS:2, 10, 15, 19, 21, 24, and 26, and a light chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to any one of SEQ ID NOS:3, 11, 16, 20, 22, and 27. In some embodiments, an agonist anti-TREM2 antibody comprises: a heavy chain variable region comprising the amino acid sequence of any one of SEQ ID NOS:2, 10, 15, 19, 21, 24, and 26, and a light chain variable region comprising the amino acid sequence of any one of SEQ ID NOS:3, 11, 16, 20, 22, and 27.

In some embodiments, an agonist anti-TREM2 antibody comprises:

(a) a VH sequence that has at least 85% sequence identity to SEQ ID NO:2 and a VL sequence has at least 85% sequence identity to SEQ ID NO:3; or

(b) a VH sequence that has at least 85% sequence identity to SEQ ID NO: 10 and a VL sequence has at least 85% sequence identity to SEQ ID NO: 11; or

(c) a VH sequence that has at least 85% sequence identity to SEQ ID NO: 15 and a VL sequence has at least 85% sequence identity to SEQ ID NO: 16; or

(d) a VH sequence that has at least 85% sequence identity to SEQ ID NO: 19 and a VL sequence has at least 85% sequence identity to SEQ ID NO:20; or

(e) a VH sequence that has at least 85% sequence identity to SEQ ID NO:21 and a VL sequence has at least 85% sequence identity to SEQ ID NO:20; or (f) a VH sequence that has at least 85% sequence identity to SEQ ID NO: 19 and a VL sequence has at least 85% sequence identity to SEQ ID NO:22; or

(g) a VH sequence that has at least 85% sequence identity to SEQ ID NO:21 and a VL sequence has at least 85% sequence identity to SEQ ID NO:22; or

(h) a VH sequence that has at least 85% sequence identity to SEQ ID NO:24 and a VL sequence has at least 85% sequence identity to SEQ ID NO:20; or

(i) a VH sequence that has at least 85% sequence identity to SEQ ID NO:26 and a VL sequence has at least 85% sequence identity to SEQ ID NO:20; or

(j) a VH sequence that has at least 85% sequence identity to SEQ ID NO:24 and a VL sequence has at least 85% sequence identity to SEQ ID NO:22; or

(k) a VH sequence that has at least 85% sequence identity to SEQ ID NO:26 and a VL sequence has at least 85% sequence identity to SEQ ID NO:22; or

(l) a VH sequence that has at least 85% sequence identity to SEQ ID NO:24 and a VL sequence has at least 85% sequence identity to SEQ ID NO:27.

In some embodiments, an agonist anti-TREM2 antibody comprises one or more sequences that are encompassed by a consensus sequence disclosed herein. As a non-limiting example, consensus sequences can be identified by aligning heavy chain or light chain sequences (e.g., CDRs) for antibodies that are from the same (or similar) germlines. In some embodiments, consensus sequences may be generated from antibodies that contain sequences that are of the same (or similar) length and/or have at least one highly similar CDR (e.g., a highly similar CDR3). In some embodiments, such sequences in these antibodies may be aligned and compared to identify conserved amino acids or motifs (i.e., where alteration in sequences may alter protein function) and/or regions where variation occurs the sequences (i.e., where variation of sequence is not likely to significantly affect protein function). Alternatively, consensus sequences can be identified by aligning heavy chain or light chain sequences (e.g., CDRs) for antibodies that bind to the same or similar (e.g., overlapping) epitopes to determine conserved amino acids or motifs (i.e., where alteration in sequences may alter protein function) and regions where variation occurs in alignment of sequences (i.e., where variation of sequence is not likely to significantly affect protein function). In some embodiments, one or more consensus sequences can be identified for antibodies that recognize the same or similar epitope as an agonist anti-TREM2 antibody as disclosed herein. Exemplary consensus sequences include SEQ ID NOS:28-32. In the consensus sequences of SEQ ID NOS:28-32, the capitalized letter represents an amino acid residue that is absolutely conserved among the aligned sequences (e.g., aligned CDR sequences), while an “X” or a Greek letter (e.g., “a,” “ ,” “y,” “6,” “a,” or “cp”) represents an amino acid residue that is not absolutely conserved among the aligned sequences. It will be appreciated that, when selecting an amino acid to insert at a position marked by an “X” or by a Greek letter, in some embodiments the amino acid is selected from those amino acids found at the corresponding position in the aligned sequences.

Thus, in some embodiments, an agonist anti-TREM2 antibody comprises:

(a) a CDR-H1 sequence comprising the sequence of G-F-T-F-T-ae-F-Y-M-S (SEQ ID NO:28), wherein CLG is D or N;

(b) a CDR-H2 sequence comprising the sequence of V-I-R-N-Ps-Pe-N-Ps-Y- T-P11-P12-Y-N-P-S-V-K-G (SEQ ID NO:29), wherein p₅ is K or R; p₆ is A or P; p₈ is G or A; Pn is A or T; and P12 is G or D;

(c) a CDR-H3 sequence comprising the sequence of yi-R-L-y4-Y-G-F-D-Y (SEQ ID NO:30), wherein yi is A or T; and yj is T or S;

(d) a CDR-L1 sequence comprising the sequence of Q-S-S-K-S-L-L-H-S-610- G-K-T-Y-L-N (SEQ ID NO:31), wherein 5io is N or T;

(e) a CDR-L2 sequence comprising the sequence of WMSTRAS (SEQ ID NO:8); and

(f) a CDR-L3 sequence comprising the sequence of Q-Q-F-L-E-(|)6-P-F-T (SEQ ID NO:32), wherein <|>6 is Y or F.

In some embodiments, an agonist anti-TREM2 antibody comprises a CDR-H1 sequence that is selected from SEQ ID NOS:4 and 12. In some embodiments, an agonist anti-TREM2 antibody comprises a CDR-H2 sequence that is selected from SEQ ID NOS:5, 13, and 25. In some embodiments, an agonist anti-TREM2 antibody comprises a CDR-H3 sequence that is selected from SEQ ID NOS:6, 14, and 17. In some embodiments, an agonist anti-TREM2 antibody comprises a CDR-L1 sequence that is selected from SEQ ID NOS:7 and 23. In some embodiments, an agonist anti-TREM2 antibody comprises a CDR-L3 sequence is selected from SEQ ID NOS:9 and 18.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to any one of SEQ ID NOS:2, 10, 15, 19, 21, 24, and 26. In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising the amino acid sequence of any one of SEQ ID NOS :2, 10, 15, 19, 21, 24, and 26. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to any one of SEQ ID NOS:3, 11, 16, 20, 22, and 27. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising the amino acid sequence of any one of SEQ ID NOS:3, 11, 16, 20, 22, and 27.

Clone CL0020188 and Associated Antibodies

In some embodiments, an agonist anti-TREM2 antibody comprises a CDR-H1 sequence comprising the amino acid sequence of SEQ ID NO:4, a CDR-H2 sequence comprising the amino acid sequence of SEQ ID NO:5, a CDR-H3 sequence comprising the amino acid sequence of SEQ ID NO: 17, a CDR-L1 sequence comprising the amino acid sequence of SEQ ID NO:7, a CDR-L2 sequence comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 sequence comprising the amino acid sequence of SEQ ID NO: 18.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 15. In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 15.

In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 16. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising the amino acid sequence of SEQ ID NO: 16.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 15 and a light chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 16. In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 15 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 16.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region that comprises a heavy chain CDR1-3 comprising the amino acid sequences of SEQ ID N0S:4, 5, and 17, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 15. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region that comprises a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:7, 8, and 18, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 16.

In some embodiments, an agonist anti-TREM2 antibody competes for binding with an antibody as described herein (e.g., an antibody comprising a heavy chain CDR1-3 and a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:4, 5, 17, 7, 8, and 18, respectively, or an antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 15 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 16).

In some embodiments, an agonist anti-TREM2 antibody comprises a CDR-H1 sequence comprising the amino acid sequence of SEQ ID NON, a CDR-H2 sequence comprising the amino acid sequence of SEQ ID NO:25, a CDR-H3 sequence comprising the amino acid sequence of SEQ ID NO: 17, a CDR-L1 sequence comprising the amino acid sequence of SEQ ID NO:23, a CDR-L2 sequence comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 sequence comprising the amino acid sequence of SEQ ID NO: 18.

In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a heavy chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity, such as at least 90%, 95%, or 97% sequence identity) to SEQ ID NO:24. In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:24.

In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a light chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity, such as at least 90%, 95%, or 97% sequence identity) to SEQ ID NO:22. In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a light chain variable region comprising the amino acid sequence of SEQ ID NO:22.

In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a heavy chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity, such as at least 90%, 95%, or 97% sequence identity) to SEQ ID NO:24 and a light chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity, such as at least 90%, 95%, or 97% sequence identity) to SEQ ID NO:22. In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:24 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:22.

In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a heavy chain variable region that comprises a heavy chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:4, 25, and 17, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity, such as at least 90%, 95%, or 97% sequence identity) to SEQ ID NO:24. In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a light chain variable region that comprises a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:23, 8, and 18, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity, such as at least 90%, 95%, or 97% sequence identity) to SEQ ID NO:22.

In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) competes for binding with an antibody as described herein (e.g., an antibody comprising a heavy chain CDR1-3 and a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:4, 25, 17, 23, 8, and 18, respectively, or an antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:24 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:22).

In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a CDR-H1 sequence comprising the amino acid sequence of SEQ ID NO:4, a CDR-H2 sequence comprising the amino acid sequence of SEQ ID NO:25, a CDR-H3 sequence comprising the amino acid sequence of SEQ ID NO: 17, a CDR-L1 sequence comprising the amino acid sequence of SEQ ID NO:7, a CDR-L2 sequence comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 sequence comprising the amino acid sequence of SEQ ID NO:9.

In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a heavy chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity, such as at least 90%, 95%, or 97% sequence identity) to SEQ ID NO:24. In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:24. In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a light chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity, such as at least 90%, 95%, or 97% sequence identity) to SEQ ID NO:27. In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a light chain variable region comprising the amino acid sequence of SEQ ID NO:27.

In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a heavy chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity, such as at least 90%, 95%, or 97% sequence identity) to SEQ ID NO:24 and a light chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity, such as at least 90%, 95%, or 97% sequence identity) to SEQ ID NO:27. In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:24 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:27.

In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a heavy chain variable region that comprises a heavy chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:4, 25, and 17, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity, such as at least 90%, 95%, or 97% sequence identity) to SEQ ID NO:24. In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a light chain variable region that comprises a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:7, 8, and 9, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity, such as at least 90%, 95%, or 97% sequence identity) to SEQ ID NO:27.

In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) is an antibody that competes for binding with an antibody as described herein (e.g., an antibody comprising a heavy chain CDR1-3 and a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:4, 25, 17, 7, 8, and 9, respectively, or an antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:24 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:27). Clone CL0020306

In some embodiments, an agonist anti-TREM2 antibody comprises a CDR-H1 sequence comprising the amino acid sequence of SEQ ID NO:4, a CDR-H2 sequence comprising the amino acid sequence of SEQ ID NO:5, a CDR-H3 sequence comprising the amino acid sequence of SEQ ID NO:6, a CDR-L1 sequence comprising the amino acid sequence of SEQ ID NO:7, a CDR-L2 sequence comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 sequence comprising the amino acid sequence of SEQ ID NO:9.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO:2. In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:2.

In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO:3. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising the amino acid sequence of SEQ ID NO:3.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO:2 and a light chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO:3. In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:2 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:3.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region that comprises a heavy chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:4, 5, and 6, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO:2. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region that comprises a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:7, 8, and 9, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO:3. In some embodiments, an agonist anti-TREM2 antibody competes for binding with an antibody as described herein (e.g., an antibody comprising a heavy chain CDR1-3 and a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:4, 5, 6, 7, 8, and 9, respectively, or an antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:2 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:3).

Clone CL0020307

In some embodiments, an agonist anti-TREM2 antibody comprises a CDR-H1 sequence comprising the amino acid sequence of SEQ ID NO: 12, a CDR-H2 sequence comprising the amino acid sequence of SEQ ID NO: 13, a CDR-H3 sequence comprising the amino acid sequence of SEQ ID NO: 14, a CDR-L1 sequence comprising the amino acid sequence of SEQ ID NO:7, a CDR-L2 sequence comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 sequence comprising the amino acid sequence of SEQ ID NO:9.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 10. In some embodiments, an agonist anti-TREM2 antibody (e.g., or antigen binding portion) comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 10.

In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g, at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 11. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising the amino acid sequence of SEQ ID NO: 11.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g, at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 10 and a light chain variable region comprising an amino acid sequence that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO:11. In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 10 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 11.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region that comprises a heavy chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS: 12, 13, and 14, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 10. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region that comprises a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:7, 8, and 9, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 11.

In some embodiments, an agonist anti-TREM2 antibody is an antibody that competes for binding with an antibody as described herein (e.g., an antibody comprising a heavy chain CDR1-3 and a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS: 12, 13, 14, 7, 8, and 9, respectively, or an antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 10 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 11).

Clones A-D

Clone A

(a) a heavy chain CDR1 (CDR-H1) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of SYWIG (SEQ ID NO: 90), or that has up to two amino acid substitutions relative to the amino acid sequence of SYWIG (SEQ ID NO:90);

(b) a heavy chain CDR2 (CDR-H2) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of IIYPGDADARYSPSFQG (SEQ ID NO:91), or that has up to two amino acid substitutions relative to the amino acid sequence of IIYPGDADARYSPSFQG (SEQ ID NO:91);

(c) a heavy chain CDR3 (CDR-H3) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of RRQGIFGDALDF (SEQ ID NO:92), or that has up to two amino acid substitutions relative to the amino acid sequence of RRQGIFGDALDF (SEQ ID NO: 92);

(d) a light chain CDR1 (CDR-L1) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of RASQSVSSNLA (SEQ ID NO: 86), or that has up to two amino acid substitutions relative to the amino acid sequence of RASQSVSSNLA (SEQ ID NO: 86);

(e) a light chain CDR2 (CDR-L2) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of G ASTRAT (SEQ ID NO: 87), or that has up to two amino acid substitutions relative to the amino acid sequence of GASTRAT (SEQ ID NO:87); and

(f) a light chain CDR3 (CDR-L3) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of LQDNNFPPT (SEQ ID NO:88), or that has up to two amino acid substitutions relative to the amino acid sequence of LQDNNFPPT (SEQ ID NO:88).

(a) a CDR-H1 sequence comprising the amino acid sequence of SEQ ID NO:90;

(b) a CDR-H2 sequence comprising the amino acid sequence of SEQ ID NO:91;

(c) a CDR-H3 sequence comprising the amino acid sequence of SEQ ID NO: 92;

(d) a CDR-L1 sequence comprising the amino acid sequence of SEQ ID NO:86;

(e) a CDR-L2 sequence comprising the amino acid sequence of SEQ ID NO: 87; and

(f) a CDR-L3 sequence comprising the amino acid sequence of SEQ ID NO:88.

In some embodiments, an agonist anti-TREM2 antibody comprises two, three, four, five, or all six of (a)-(f). In some embodiments, an agonist anti-TREM2 antibody comprises the CDR- H1 of (a), the CDR-H2 of (b), and the CDR-H3 of (c). In some embodiments, an agonist anti- TREM2 antibody comprises the CDR-L1 of (d), the CDR-L2 of (e), and the CDR-L3 of (f).

In some embodiments, an agonist anti-TREM2 antibody comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO: 90, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:91, a CDR-H3 comprising the amino acid sequence of SEQ ID NO:92, a CDR-L1 comprising the amino acid sequence of SEQ ID NO:86, a CDR-L2 comprising the amino acid sequence of SEQ ID NO: 87, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 88.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO:89. In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:89.

In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO:85. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising the amino acid sequence of SEQ ID NO:85.

In some embodiments, an agonist anti-TREM2 antibody comprises: a heavy chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 89, and a light chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO:85. In some embodiments, an agonist anti-TREM2 antibody comprises: a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 89, and a light chain variable region comprising the amino acid sequence of SEQ ID NO:85.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region that comprises a heavy chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:90, 91, and 92, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO:89. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region that comprises a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:86, 87, and 88, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO:85.

In some embodiments, an agonist anti-TREM2 antibody competes for binding with an antibody as described herein (e.g., an antibody comprising a heavy chain CDR1-3 and a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:90, 91, 92, 86, 87, and 88, respectively, or an antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:89 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:85).

Clone B

(a) a heavy chain CDR1 (CDR-H1) comprising a sequence that has at least 90% sequence identity to the amino acid sequence NYWIA (SEQ ID NO:98), or that has up to two amino acid substitutions relative to the amino acid sequence of NYWIA (SEQ ID NO:98);

(b) a heavy chain CDR2 (CDR-H2) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of IIYPGDSDTRYSPSFQG (SEQ ID NO:99), or that has up to two amino acid substitutions relative to the amino acid sequence of IIYPGDSDTRYSPSFQG (SEQ ID NO:99);

(c) a heavy chain CDR3 (CDR-H3) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of QRTFYYDSSGYFDY (SEQ ID NO: 100), or that has up to two amino acid substitutions relative to the amino acid sequence of QRTFYYDSSGYFDY (SEQ ID NO: 100);

(d) a light chain CDR1 (CDR-L1) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of RASQGISNWLA (SEQ ID NO:94), or that has up to two amino acid substitutions relative to the amino acid sequence of RASQGISNWLA (SEQ ID NO: 94);

(e) a light chain CDR2 (CDR-L2) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of AASSLQV (SEQ ID NO:95), or that has up to two amino acid substitutions relative to the amino acid sequence of AASSLQV (SEQ ID NO:95); and

(f) a light chain CDR3 (CDR-L3) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of QQADSFPRN (SEQ ID NO:96), or that has up to two amino acid substitutions relative to the amino acid sequence of QQADSFPRN (SEQ ID NO:96).

(a) a CDR-H1 sequence comprising the amino acid sequence of SEQ ID NO:98;

(b) a CDR-H2 sequence comprising the amino acid sequence of SEQ ID NO:99;

(c) a CDR-H3 sequence comprising the amino acid sequence of SEQ ID NO: 100;

(d) a CDR-L1 sequence comprising the amino acid sequence of SEQ ID NO: 94;

(e) a CDR-L2 sequence comprising the amino acid sequence of SEQ ID NO: 95; and

(f) a CDR-L3 sequence comprising the amino acid sequence of SEQ ID NO:96.

In some embodiments, an agonist anti-TREM2 antibody comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO: 98, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:99, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 100, a CDR-L1 comprising the amino acid sequence of SEQ ID NO:94, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:95, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:96.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO:97. In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:97.

In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 93. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising the amino acid sequence of SEQ ID NO: 93.

In some embodiments, an agonist anti-TREM2 antibody comprises: a heavy chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 97, and a light chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 93. In some embodiments, an agonist anti-TREM2 antibody comprises: a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:97, and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 93.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region that comprises a heavy chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:98, 99, and 100, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO:97. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region that comprises a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:94, 95, and 96, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO:93.

In some embodiments, an agonist anti-TREM2 antibody competes for binding with an antibody as described herein (e.g., an antibody comprising a heavy chain CDR1-3 and a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS:98, 99, 100, 94, 95, and 96, respectively, or an antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:97 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:93).

Clone C

(a) a heavy chain CDR1 (CDR-H1) comprising a sequence that has at least 90% sequence identity to the amino acid sequence SYWIA (SEQ ID NO: 106), or that has up to two amino acid substitutions relative to the amino acid sequence of SYWIA (SEQ ID NO: 106);

(c) a heavy chain CDR3 (CDR-H3) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of QRTFYYDSSDYFDY (SEQ ID NO: 107), or that has up to two amino acid substitutions relative to the amino acid sequence of QRTFYYDSSDYFDY (SEQ ID NO: 107);

(d) a light chain CDR1 (CDR-L1) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of RASQGISSWLA (SEQ ID NO: 102), or that has up to two amino acid substitutions relative to the amino acid sequence of RASQGISSWLA (SEQ ID NO: 102);

(e) a light chain CDR2 (CDR-L2) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of AASSLQN (SEQ ID NO: 103), or that has up to two amino acid substitutions relative to the amino acid sequence of AASSLQN (SEQ ID NO: 103); and

(f) a light chain CDR3 (CDR-L3) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of QQADSFPRT (SEQ ID NO: 104), or that has up to two amino acid substitutions relative to the amino acid sequence of QQADSFPRT (SEQ ID

NO: 104).

In some embodiments, an agonist anti-TREM2 antibody comprises two, three, four, five, or all six of (a)-(f). In some embodiments, an agonist anti-TREM2 antibody comprises the CDR- H1 of (a), the CDR-H2 of (b), and the CDR-H3 of (c). In some embodiments, an agonist anti¬

TREM2 antibody comprises the CDR-L1 of (d), the CDR-L2 of (e), and the CDR-L3 of (f). In some embodiments, a CDR having up to two amino acid substitutions has one amino acid substitution relative to the reference sequence. In some embodiments, a CDR having up to two amino acid substitutions has two amino acid substitutions relative to the reference sequence. In some embodiments, the up to two amino acid substitutions are conservative substitutions.

(a) a CDR-H1 sequence comprising the amino acid sequence of SEQ ID

NO: 106;

(b) a CDR-H2 sequence comprising the ammo acid sequence of SEQ ID

NO:99;

(c) a CDR-H3 sequence comprising the amino acid sequence of SEQ ID

NO: 107; (d) a CDR-L1 sequence comprising the amino acid sequence of SEQ ID NO: 102;

(e) a CDR-L2 sequence comprising the amino acid sequence of SEQ ID NO: 103; and

(f) a CDR-L3 sequence comprising the amino acid sequence of SEQ ID NO: 104.

In some embodiments, an agonist anti-TREM2 antibody comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO: 106, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:99, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 107, a CDR-L1 comprising the amino acid sequence of SEQ ID NO: 102, a CDR-L2 comprising the amino acid sequence of SEQ ID NO: 103, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 104.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 105. In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 105.

In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 101. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising the amino acid sequence of SEQ ID NO: 101.

In some embodiments, an agonist anti-TREM2 antibody comprises: a heavy chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 105, and a light chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 101. In some embodiments, an agonist anti-TREM2 antibody comprises: a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 105, and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 101. In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region that comprises a heavy chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS: 106, 99, and 107, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 105. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region that comprises a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS: 102, 103, and 104, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 101.

In some embodiments, an agonist anti-TREM2 antibody competes for binding with an antibody as described herein (e.g., an antibody comprising a heavy chain CDR1-3 and a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS: 106, 99, 107, 102, 103, and 104, respectively, or an antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 105 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 101).

Clone D

(a) a heavy chain CDR1 (CDR-H1) comprising a sequence that has at least 90% sequence identity to the amino acid sequence Y f'SSQWM'x (SEQ ID NO: 113), or that has up to two amino acid substitutions relative to the amino acid sequence of YAFSSQWMN (SEQ ID NO: 113);

(b) a heavy chain CDR2 (CDR-H2) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of RIYPGGGDTNYAGKFQG (SEQ ID NO: 114), or that has up to two amino acid substitutions relative to the amino acid sequence of RIYPGGGDTNYAGKFQG (SEQ ID NO: 114);

(c) a heavy chain CDR3 (CDR-H3) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of ARLLRNQPGESYAMDY (SEQ ID NO: 115), or that has up to two amino acid substitutions relative to the amino acid sequence of ARLLRNQPGESYAMDY (SEQ ID NO: 115);

(d) a light chain CDR1 (CDR-L1) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of RSSQSLVHSNRYTYLH (SEQ ID NO: 109), or that has up to two amino acid substitutions relative to the amino acid sequence of RSSQSLVHSNRYTYLH (SEQ ID NO: 109); (e) a light chain CDR2 (CDR-L2) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of KVSNRFS (SEQ ID NO: 110), or that has up to two amino acid substitutions relative to the amino acid sequence of KVSNRFS (SEQ ID NO: 110); and

(f) a light chain CDR3 (CDR-L3) comprising a sequence that has at least 90% sequence identity to the amino acid sequence of SQSTR.VPYT (SEQ ID NO: 111), or that has up to two amino acid substitutions relative to the amino acid sequence of SQSTRVPY T (SEQ ID NO: 111).

(a) a CDR-H1 sequence comprising the amino acid sequence of SEQ ID NO: 113;

(b) a CDR-H2 sequence comprising the amino acid sequence of SEQ ID NO: 114;

(c) a CDR-H3 sequence comprising the amino acid sequence of SEQ ID NO:115;

(d) a CDR-L1 sequence comprising the amino acid sequence of SEQ ID NO: 109;

(e) a CDR-L2 sequence comprising the amino acid sequence of SEQ ID NO: 110; and

(f) a CDR-L3 sequence comprising the amino acid sequence of SEQ ID NO: 111.

In some embodiments, an agonist anti-TREM2 antibody comprises two, three, four, five, or all six of (a)-(f). In some embodiments, an agonist anti-TREM2 antibody comprises the CDR- H1 of (a), the CDR-H2 of (b), and the CDR-H3 of (c). In some embodiments, an agonist anti- TREM2 antibody comprises the CDR-L1 of (d), the CDR-L2 of (e), and the CDR-L3 of (f). In some embodiments, an agonist anti-TREM2 antibody comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO: 113, a CDR-H2 comprising the amino acid sequence of SEQ ID NO: 114, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 115, a CDR-L1 comprising the amino acid sequence of SEQ ID NO: 109, a CDR-L2 comprising the amino acid sequence of SEQ ID NO: 110, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 111.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 112. In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 112.

In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 108. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region comprising the amino acid sequence of SEQ ID NO: 108.

In some embodiments, an agonist anti-TREM2 antibody comprises: a heavy chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 112, and a light chain variable region comprising an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity to SEQ ID NO: 108. In some embodiments, an agonist anti-TREM2 antibody comprises: a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 112, and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 108.

In some embodiments, an agonist anti-TREM2 antibody comprises a heavy chain variable region that comprises a heavy chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS: 113, 114, and 115, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 112. In some embodiments, an agonist anti-TREM2 antibody comprises a light chain variable region that comprises a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS: 109, 110, and 111, respectively, and that has at least 85% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity) to SEQ ID NO: 108.

In some embodiments, an agonist anti-TREM2 antibody competes for binding with an antibody as described herein (e.g., an antibody comprising a heavy chain CDR1-3 and a light chain CDR1-3 comprising the amino acid sequences of SEQ ID NOS: 113, 114, 115, 109, 110, and 111, respectively, or an antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 112 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 108).

Binding Characteristics

In some embodiments, an agonist antibody as described herein that specifically binds to a TREM2 protein binds to TREM2 that is expressed on a cell (e.g., a primary cell or cell line that endogenously expresses TREM2, such as human macrophages, or a primary cell or cell line that has been engineered to express TREM2). In some embodiments, an agonist antibody that specifically binds to a TREM2 protein as described herein binds to purified or recombinant TREM2 protein of a portion thereof, or to a chimeric protein comprising TREM2 or a portion thereof (e.g., an Fc-fusion protein comprising TREM2 or an Fc-fusion protein comprising the ecto-domain of TREM2).

In some embodiments, an agonist antibody that specifically binds to human TREM2 protein exhibits cross-reactivity with one or more other TREM2 proteins of another species. In some embodiments, an agonist antibody that specifically binds to human TREM2 protein exhibits cross-reactivity with a cynomolgus monkey (“cyno”) TREM2 protein. In some embodiments, an agonist antibody that specifically binds to human TREM2 protein exhibits cross-reactivity with a mouse TREM2 protein. In some embodiments, an agonist anti-TREM2 antibody exhibits crossreactivity with human TREM2, cyno TREM2, and mouse TREM2.

Methods for analyzing binding affinity, binding kinetics, and cross-reactivity are known in the art. These methods include, but are not limited to, solid-phase binding assays (e.g., ELISA assay), immunoprecipitation, surface plasmon resonance (e.g., Biacore™ (GE Healthcare, Piscataway, NJ)), kinetic exclusion assays (e.g., KinExA®), flow cytometry, fluorescence- activated cell sorting (FACS), BioLayer interferometry (e.g., Octet™ (ForteBio, Inc., Menlo Park, CA)), and western blot analysis. In some embodiments, ELISA is used to determine binding affinity and/or cross-reactivity. Methods for performing ELISA assays are known in the art. In some embodiments, surface plasmon resonance (SPR) is used to determine binding affinity, binding kinetics, and/or cross-reactivity. In some embodiments, kinetic exclusion assays are used to determine binding affinity, binding kinetics, and/or cross-reactivity. In some embodiments, BioLayer interferometry assays are used to determine binding affinity, binding kinetics, and/or cross-reactivity. Epitopes Recognized by Agonist Anti-TREM2 Antibodies

In some embodiments, an agonist anti-TREM2 antibody recognizes an epitope of human TREM2 that is the same or substantially the same as the epitope recognized by an antibody clone as described herein or competes for binding with the clone. As used herein, the term “substantially the same,” as used with reference to an epitope recognized by an antibody clone as described herein, means that the agonist anti-TREM2 antibody recognizes an epitope that is identical, within, or nearly identical to (e.g., has at least 90% sequence identity to, or has one, two, or three amino acid substitutions, e.g., conservative substitutions, relative to), or has substantial overlap with (e.g., at least 50%, 60%, 70%, 80%, 90%, or 95% overlap with) the epitope recognized by the antibody clone as described herein.

In some embodiments, an agonist anti-TREM2 antibody recognizes an epitope of human TREM2 that is the same or substantially the same as the epitope recognized by an antibody clone, or competes for binding with a clone, selected from the group consisting of Clone CL0020306, Clone CL0020188, Clone CL0020307, Clone A, Clone B, Clone C, Clone D, and variants of the same.

In some embodiments, an agonist anti-TREM2 antibody binds to human TREM2 at an epitope within the stalk region of TREM2. In some embodiments, an agonist anti-TREM2 antibody recognizes an epitope of human TREM2 comprising, within, or consisting of residues 129-172 or residues 131-169 of SEQ ID NO: 1. In some embodiments, an agonist anti-TREM2 antibody recognizes an epitope of human TREM2 comprising, within, or consisting of residues 129-148 of SEQ ID NO: 1 (e.g., 143-148 of SEQ ID NO: 1). In some embodiments, an agonist anti-TREM2 antibody activates TREM2/DAP12 signaling (e.g., by inducing phosphorylation of a kinase such as Syk) and binds to human TREM2 at an epitope within the stalk region of TREM2. In some embodiments, an agonist anti-TREM2 antibody binds to human TREM2 at an epitope within the stalk region of TREM2 and inhibits cleavage of TREM2 by a protease (e.g., ADAM17).

Certain Fc Polypeptide Modifications

An agonist anti-TREM2 antibody for use a method described herein may comprise two Fc polypeptides, wherein one or both may each comprise independently selected modifications (e.g., mutations) or may be a wild-type Fc polypeptide, e.g., a human IgGl Fc polypeptide. Nonlimiting examples of mutations that can be introduced into one or both Fc polypeptides include, e.g., mutations to increase serum stability, to modulate effector function, to influence glycosylation, to reduce immunogenicity in humans, and/or to provide for knob and hole heterodimerization of the Fc polypeptides. Additionally, as described below, one or both of the Fc polypeptides may be modified to specifically binds to a transferrin receptor (c.g, a human or cynomolgus TfR, such as may be expressed on a brain endothelial cell).

In some embodiments, the Fc polypeptides may be modified to include knob and hole mutations to promote heterodimer formation and hinder homodimer formation. Generally, the modifications introduce a protuberance (“knob”) at the interface of a first polypeptide and a corresponding cavity (“hole”) in the interface of a second polypeptide, such that the protuberance can be positioned in the cavity so as to promote heterodimer formation and thus hinder homodimer formation. Protuberances are constructed by replacing small amino acid side chains from the interface of the first polypeptide with larger side chains (e.g., tyrosine or tryptophan). Compensatory cavities of identical or similar size to the protuberances are created in the interface of the second polypeptide by replacing large amino acid side chains with smaller ones (e.g., alanine or threonine). In some embodiments, such additional mutations are at a position in the Fc polypeptide that does not have a negative (e.g., inhibitory) effect on binding of a Fc polypeptide to a TfR..

In one illustrative embodiment of a knob and hole approach for dimerization, position 366 (numbered according to the EU numbering scheme) of one of the Fc polypeptides present in the proteins described herein comprises a tryptophan in place of a native threonine. The other Fc polypeptide in the dimer has a valine at position 407 (numbered according to the EU numbering scheme) in place of the native tyrosine. The other Fc polypeptide may further comprise a substitution in which the native threonine at position 366 (numbered according to the EU numbering scheme) is substituted with a serine and a native leucine at position 368 (numbered according to the EU numbering scheme) is substituted with an alanine. Thus, one of the Fc polypeptides of an anti-TREM2 binding molecule of the disclosure has the T366W knob mutation and the other Fc polypeptide has the Y407V mutation, which is typically accompanied by the T366S and L368A hole mutations.

In some embodiments, one or both Fc polypeptides may also be engineered to contain other modifications for heterodimerization, e.g., electrostatic engineering of contact residues within a CH3-CH3 interface that are naturally charged or hydrophobic patch modifications.

In some embodiments, one or both Fc polypeptides in a molecule as described herein may comprise modifications that reduce effector function, i.e., having a reduced ability to induce certain biological functions upon binding to an Fc receptor expressed on an effector cell that mediates the effector function. Examples of antibody effector functions include, but are not limited to, Clq binding and complement dependent cytotoxicity (CDC), Fc receptor binding, antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cell-mediated phagocytosis (ADCP), down-regulation of cell surface receptors (e.g., B cell receptor), and B-cell activation. Effector functions may vary with the antibody class. For example, native human IgGl and IgG3 antibodies can elicit ADCC and CDC activities upon binding to an appropriate Fc receptor present on an immune system cell; and native human IgGl, IgG2, IgG3, and IgG4 can elicit ADCP functions upon binding to the appropriate Fc receptor present on an immune cell.

In some embodiments, one Fc polypeptide may include one or more modifications that modulate effector function or both Fc polypeptides may each independently include one or more modifications that modulate effector function.

In some embodiments, one or both Fc polypeptides may comprise independently selected modifications that reduce or eliminate effector function. Illustrative Fc polypeptide mutations that reduce effector function include, but are not limited to, substitutions in a CH2 domain, e.g., at positions 234 and 235, according to the EU numbering scheme. For example, in some embodiments, one or both Fc polypeptides can comprise alanine residues at positions 234 and 235. Thus, one or both Fc polypeptides may have L234A and L235A (LALA) substitutions.

Additional Fc polypeptide mutations that modulate an effector function include, but are not limited to, the following: position 329 may have a mutation in which proline is substituted with a glycine, arginine, serine, or an amino acid residue large enough to destroy the Fc/Fcy receptor interface that is formed between proline 329 of the Fc and tryptophan residues Trp 87 and Trp 110 of FcyRIII. Additional illustrative substitutions include S228P, E233P, L235E, N297A, N297D, N297G, and P331S, according to the EU numbering scheme. Multiple substitutions may also be present, e.g., L234A and L235A of a human IgGl Fc region; L234A, L235A, and P329G of a human IgGl Fc region (LALAPG); L234A, L235A, and P329S of a human IgGl Fc region (LALAPS); S228P and L235E of a human IgG4 Fc region; L234A and G237A of a human IgGl Fc region; L234A, L235A, and G237A of a human IgGl Fc region; V234A and G237A of a human IgG2 Fc region; L235A, G237A, and E318A of a human IgG4 Fc region; and S228P and L236E of a human IgG4 Fc region, according to the EU numbering scheme. In some embodiments, one or both Fc polypeptides may have one or more amino acid substitutions that modulate ADCC, e.g., substitutions at positions 298, 333, and/or 334, according to the EU numbering scheme.

In certain aspects, one or both of the Fc polypeptides (e.g., modified Fc polypeptides) present in a molecule as described herein, can comprise an FcRn binding site. In some embodiments, the FcRn binding site is within the Fc polypeptide or a fragment thereof. In some embodiments, the FcRn binding site comprises a native FcRn binding site. In some embodiments, the FcRn binding site does not comprise amino acid changes relative to the amino acid sequence of a native FcRn binding site. In some embodiments, the native FcRn binding site is an IgG binding site, e.g., a human IgG binding site. In some embodiments, the FcRn binding site comprises a modification that alters FcRn binding.

In some embodiments, an FcRn binding site has one or more amino acid residues that are mutated, e.g., substituted, wherein the mutation(s) increase serum half-life or do not substantially reduce serum half-life (i.e., reduce serum half-life by no more than 25% compared to a counterpart Fc polypeptide having the wild-type residues at the mutated positions when assayed under the same conditions). In some embodiments, an FcRn binding site has one or more amino acid residues that are substituted at positions 251-256, 428, and 433-436, according to the EU numbering scheme.

In some embodiments, one or more residues at or near an FcRn binding site are mutated, relative to a native human IgG sequence, to extend serum half-life of the polypeptide.

In some embodiments, the mutations are M428L and/or N434S. In some embodiments, an Fc polypeptide further comprises the mutation N434S with or without M428L. In some embodiments, an Fc polypeptide comprises a mutation at one, two, or all three of positions T307, E380, and N434, according to the EU numbering scheme. In some embodiments, the mutations are T307Q and N434A. In some embodiments, an Fc polypeptide comprises mutations T307A, E380A, and N434A. In some embodiments, an Fc polypeptide comprises mutations at positions T250 and M428, according to the EU numbering scheme. In some embodiments, the Fc polypeptide comprises mutations T250Q and/or M428L. In some embodiments, an Fc polypeptide comprises mutations at positions M428 and N434, according to the EU numbering scheme. In some embodiments, the Fc polypeptide comprises mutations M428L and N434S (LS). In some embodiments, a molecule as described herein can comprise two Fc polypeptides, wherein each of the two Fc polypeptides comprises M428L and/or N434S substitutions. In some embodiments, the Fc polypeptide comprises an N434S or N434A mutation. In some embodiments, a molecule as described herein can comprise two Fc polypeptides, wherein each of the two Fc polypeptides comprises an N434S or N434A substitution.

By way of a non-limiting example, one or both of the Fc polypeptide sequences may independently comprise one or more modifications selected from the group consisting of a knob mutation (e.g., T366W as numbered according to the EU numbering scheme), hole mutations (e.g., T366S, L368A, and Y407V as numbered according to the EU numbering scheme), L234A, L235A, R292C, N297G, V302C, P329G, P331S, D356E, L358M, M428L, E430G, and N434S. In some embodiments, the C-terminal Lys residue is removed in an Fc polypeptide described herein (i.e., the Lys residue at position 447, according to the EU numbering scheme).

Thus, in certain embodiments, an agonist anti-TREM2 antibody as described herein may comprise one or more wildtype Fc polypeptides or may comprise one or more Fc polypeptides that comprise modifications (e.g., a modification described herein). For example, in certain embodiments an agonist anti-TREM2 antibody may comprise a first and a second Fc polypeptide, wherein the first Fc polypeptide comprises a sequence that has at least 80% sequence identity SEQ ID NO:38 or 119, and the second Fc polypeptide may comprise a sequence that has at least 80% sequence identity to SEQ ID NO:38 or 119. In certain embodiments an agonist anti-TREM2 antibody may comprise a first and a second Fc polypeptide, wherein the first Fc polypeptide comprises a sequence that has at least 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity SEQ ID NO:38 or 119, and the second Fc polypeptide may comprise a sequence that has at least 85%, 90%, or 95%, 96%, 97%, 98%, 99% or 100% sequence identity to SEQ ID NO:38 or 119.

In particular embodiments, an agonist anti-TREM2 antibody may comprise (i) a first heavy chain (HC) comprising 1) a VH comprising a sequence that has at least 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising a sequence that has at least 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to SEQ ID NO:38 or 119; (ii) a second HC comprising 1) a VH comprising a sequence that has at least 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising a sequence that has at least 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to SEQ ID NO:38 or 119; and (iii) two light chains each comprising a VL comprising a sequence that has at least 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to a sequence selected from the group consisting of SEQ ID NOS: 22, 85, 93, 101, and 108. In particular embodiments, an agonist anti-TREM2 antibody may comprise (i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising a sequence that has at least 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to SEQ ID NO: 38; (ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising a sequence that has at least 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to SEQ ID NO:38; and (iii) two light chains each comprising a VL comprising a sequence selected from the group consisting of SEQ ID NOS: 22, 85, 93, 101, and 108. In certain embodiments, an agonist anti- TREM2 antibody may comprise (i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising a sequence that has at least 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to SEQ ID NO: 119; (ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising a sequence that has at least 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to SEQ ID NO: 119; and (iii) two light chains each comprising a VL comprising a sequence selected from the group consisting of SEQ ID NOS: 22, 85, 93, 101, and 108. In certain embodiments, (a) each VH comprises SEQ ID NO:24 and each VL comprises SEQ ID NO:22; (b) each VH comprises SEQ ID NO:89 and each VL comprises SEQ ID NO:85; (c) each VH comprises SEQ ID NO:97 and each VL comprises SEQ ID NO:93; (d) each VH comprises SEQ ID NO: 105 and each VL comprises SEQ ID NO: 101; or (e) each VH comprises SEQ ID NO: 112 and each VL comprises SEQ ID NO: 108. In certain embodiments, such an antibody comprises one or more modifications as described herein, as compared to a wildtype Fc polypeptide sequence.

Fc Modifications for Transferrin Receptor Binding

In some embodiments, an agonist anti-TREM2 antibody for use in a method as described herein may include an Fc polypeptide that comprises modifications (e.g., amino acid substitutions) that permit binding of the Fc polypeptide to a TfR. protein. Briefly, binding to a TfR. protein (e.g., to the apical domain thereof) that is expressed on, for example, a brain endothelial cell, can, in some embodiments, permit the modified Fc polypeptide or an antibody comprising the same to cross the blood-brain barrier via receptor-mediated transcytosis. In certain embodiments, receptor-mediated transcytosis can enhance or improve the ability of the protein comprising the Fc polypeptide to be present in the brain (z.e., on the luminal side of the blood-brain barrier), which can allow for improved binding to TREM2 in the CNS, and other functions, e.g., clearance, neutralization, or immunodepletion of the target, or the like.

Exemplary TfR.-binding amino acid modifications to an Fc (e.g, CH2 and/or CH3 portion, fragment, or domain), and Fc polypeptides and portions thereof that comprise the amino acid modifications, are described in PCT patent publication No. WO 2018/152326A1. These amino acid modifications, TfR.-binding Fc polypeptide sequences and TfR.-binding Fc polypeptides, and techniques for generating and testing the same are incorporated herein by reference. One or two Fc polypeptides of an Fc dimer comprised within an agonist anti-TREM2 antibody as described herein can be engineered to comprise modifications to permit binding to TfR. In certain embodiments, one Fc polypeptide of an Fc dimer comprises modifications to permit binding to TfR, and the other Fc polypeptide does not.

In some embodiments, a Fc polypeptide modified to bind to a TfR comprises a YxTEWSS (SEQ ID NO: 58) motif. In some embodiments, a Fc polypeptide modified to bind to a TfR comprises a TxxExxxxF (SEQ ID NO:59) motif. In some embodiments, a Fc polypeptide modified to bind to a TfR comprises a YxTEWSS (SEQ ID NO:58) and a TxxExxxxF (SEQ ID NO:59) motif.

In some embodiments, a Fc polypeptide modified to bind to a TfR comprises a wild-type amino acid residue at positions 380, 389, 390, and 415, according to EU numbering, wherein the wild-type amino acid residue is found at a corresponding position in SEQ ID NO:38.

In some embodiments, an agonist anti-TREM2 antibody as described herein includes an Fc polypeptide having the following amino acids: Trp, Leu, or Glu at position 380; Tyr or Phe at position 384; Thr at position 386; Glu at position 387; Trp at position 388; Ser, Ala, or Vai at position 389; Ser or Asn at position 390; Thr or Ser at position 413; Glu or Ser at position 415; Glu at position 416; and Phe at position 421, according to EU numbering.

In some embodiments, an agonist anti-TREM2 antibody as described herein includes an Fc polypeptide that 1) comprises a sequence that has at least 80%, 85%, 90%, or 95% sequence identity to a sequence selected from the group consisting of SEQ ID NOS:38, 39, 46, 47, 49, 50, 61, 63, 68, 70, 84, and 116-124; and 2) comprises: Trp, Leu, or Glu at position 380; Tyr or Phe at position 384; Thr at position 386; Glu at position 387; Trp at position 388; Ser, Ala, or Vai at position 389; Ser or Asn at position 390; Thr or Ser at position 413; Glu or Ser at position 415; Glu at position 416; and Phe at position 421, according to EU numbering.

In some embodiments, an agonist anti-TREM2 antibody as described herein includes an Fc polypeptide that 1) comprises a sequence that has at least 80%, 85%, 90% or 95% sequence identity to a sequence selected from the group consisting of SEQ ID NOS: 46, 47, 49, 50, 68, 70,

117, 118, and 121-124; and 2) comprises: Trp, Leu, or Glu at position 380; Tyr or Phe at position 384; Thr at position 386; Glu at position 387; Trp at position 388; Ser, Ala, or Vai at position 389; Ser or Asn at position 390; Thr or Ser at position 413; Glu or Ser at position 415; Glu at position 416; and Phe at position 421, according to EU numbering.

In some embodiments, an agonist anti-TREM2 antibody as described herein includes an Fc polypeptide that 1) comprises a sequence that has at least 80%, 85%, 90% or 95% sequence identity to a sequence selected from the group consisting of SEQ ID NOS: 47, 50, 68, 70, 117,

118, 122, and 124; and 2) comprises: Trp, Leu, or Glu at position 380; Tyr or Phe at position 384; Thr at position 386; Glu at position 387; Trp at position 388; Ser, Ala, or Vai at position 389; Ser or Asn at position 390; Thr or Ser at position 413; Glu or Ser at position 415; Glu at position 416; and Phe at position 421, according to EU numbering.

In some embodiments, the Fc polypeptide has the following amino acids: Trp at position 380; Tyr at position 384; Thr at position 386; Glu at position 387; Trp at position 388; Ser at position 389; Ser at position 390; Thr at position 413; Glu at position 415; Glu at position 416; and Phe at position 421, according to EU numbering.

In some embodiments, the Fc polypeptide has the following amino acids: Glu at position 380; Phe at position 384; Thr at position 386; Glu at position 387; Trp at position 388; Ser at position 389; Asn at position 390; Ser at position 413; Glu at position 415; Glu at position 416; and Phe at position 421, according to EU numbering.

In some embodiments, the Fc polypeptide has the following amino acids: Glu at position 380; Tyr at position 384; Thr at position 386; Glu at position 387; Trp at position 388; Vai at position 389; Asn at position 390; Thr at position 413; Glu at position 415; Glu at position 416; and Phe at position 421, according to EU numbering.

In some embodiments, the Fc polypeptide has the following amino acids: Glu at position 380; Tyr at position 384; Thr at position 386; Glu at position 387; Trp at position 388; Ser at position 389; Asn at position 390; Ser at position 413; Glu at position 415; Glu at position 416; and Phe at position 421, according to EU numbering.

In some embodiments, the Fc polypeptide comprises a sequence having at least 90%, 95%, 96%, 97%, 98% or 99% identity to an amino acid sequence set forth in any one of SEQ ID NOS: 46, 47, 49, 50, 68, 70, 117, 118, 121-124. In some embodiments, the Fc polypeptide comprises a sequence having at least 90%, 95%, 96%, 97%, 98% or 99% identity to an amino acid sequence set forth in any one of SEQ ID NOS: 47, 50, 68, 70, 117, 118, 122, and 124. In some embodiments, the Fc polypeptide comprises or consists of the amino acid sequence set forth in any one of SEQ ID NOS: 47, 50, 68, 70, 117, 118, 122, and 124.

Additional examples of Fc polypeptides modified to bind to TfR. are described in Table 2.

In some embodiments, an agonist anti-TREM2 antibody as described herein comprises a first and a second Fc polypeptide, wherein the first polypeptide is modified to specifically bind to a TfR. as described herein. In certain embodiments, the second Fc polypeptide is not modified to specifically bind to TfR.. In certain embodiments, the second Fc polypeptide comprises a sequence that has at least 90%, 95%, 96%, 97%, 98% or 99% sequence identity to a sequence selected from the group consisting of SEQ ID NOS: 38, 39, 61, 63, 84, 116, 119, and 120. In certain embodiments, the second Fc polypeptide comprises a sequence that has at least 90%, 95%, 96%, 97%, 98% or 99% sequence identity to a sequence selected from the group consisting of SEQ ID NOS: 39, 61, 63, 84, 116 and 120. In some embodiments, second Fc polypeptide comprises or consists of the amino acid sequence set forth in any one of SEQ ID NOS: 39, 61, 63, 84, 116 and 120.

Embodiments of Certain Agonist Anti-TREM2 Antibodies comprising a Modified TfR Binding Fc Polypeptide

Variable regions for TREM2 binding, as well as Fc modifications for binding TfR. are described above and in Table 2. Certain exemplary combinations of these sequences are included below.

In certain embodiments, an Fc polypeptide present within an agonist anti-TREM2 antibody described herein is modified to specifically bind to a TfR.. For example, in certain embodiments, the first Fc polypeptide comprises a sequence having at least 85%, 90%, or 95% identity to an amino acid sequence selected from the group consisting of SEQ ID NOS: 47 and 68, and the second Fc polypeptide comprises a sequence having at least 85%, 90%, or 95% identity to an amino acid sequence selected from the group consisting of SEQ ID NOS: 39, 63, 61 and 84. In certain embodiments, the first Fc polypeptide comprises a sequence selected from the group consisting of SEQ ID NOS:47 and 68, and the second Fc polypeptide comprises a sequence selected from the group consisting of SEQ ID NOS: 39, 63, 61 and 84.

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) comprising 1) a VH comprising a sequence having at least 85%, 90%, 95% or 100% identity to any one of SEQ ID NOS:24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:47 or 68;

(ii) a second HC comprising 1) a VH comprising a sequence having at least 85%, 90%, 95% or 100% identity to any one of SEQ ID NOS:24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:39, 63, 61 or 84; and

(iii) two light chains each independently comprising a VL comprising a sequence having at least 85%, 90%, 95% or 100% identity to any one of SEQ ID NOS:22, 85, 93, 101, and 108.

In certain embodiments, the agonist anti-TREM2 antibody comprises: (i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS:24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:47 (e.g., 100% identity to SEQ ID NO:47);

(ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS:24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:39 (e.g., 100% identity to SEQ ID NO:39); and

(iii) two light chains each comprising a VL comprising a sequence selected from the group consisting of SEQ ID NOS:22, 85, 93, 101, and 108.

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:47 (e.g., 100% identity to SEQ ID NO:47);

(ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:61 (e.g., 100% identity to SEQ ID NO:61); and

(iii) two light chains each comprising a VL comprising a sequence selected from the group consisting of SEQ ID NOS: 22, 85, 93, 101, and 108.

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:68 (e.g., 100% identity to SEQ ID NO: 68);

(ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and the second Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:63 (e.g., 100% identity to SEQ ID NO:63); and

In certain embodiments, the agonist anti-TREM2 antibody comprises: (i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:68 (e.g., 100% identity to SEQ ID NO: 68);

(ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:84 (e.g., 100% identity to SEQ ID NO: 84); and

In certain embodiments:

(a) each VH comprises SEQ ID NO:24 and each VL comprises SEQ ID NO:22;

(b) each VH comprises SEQ ID NO:89 and each VL comprises SEQ ID NO:85;

(c) each VH comprises SEQ ID NO:97 and each VL comprises SEQ ID NO:93;

(d) each VH comprises SEQ ID NO: 105 and each VL comprises SEQ ID NO: 101; or

(e) each VH comprises SEQ ID NO: 112 and each VL comprises SEQ ID NO: 108.

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) that comprises a sequence having at least 90%, 95% or 100% identity to any one of SEQ ID NOS:48 and 69;

(ii) a second HC that comprises a sequence having at least 90%, 95% or 100% identity to any one of SEQ ID NOS:53, 52, 73 and 72; and

(iii) a first and a second light chain (LC) that each independently comprise a sequence having at least 90%, 95% or 100% identity to SEQ ID NO: 54.

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) that comprises or consists of the amino acid sequence set forth in SEQ ID NO:48;

(ii) a second HC that comprises or consists of the amino acid sequence set forth in SEQ ID NO:53; and

(iii) a first and a second light chain (LC) that each comprises or consists of the amino acid sequence set forth in SEQ ID NO:54.

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) that comprises or consists of the amino acid sequence set forth in SEQ ID NO:48; (ii) a second HC that comprises or consists of the amino acid sequence set forth in SEQ ID NO: 52; and

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) that comprises or consists of the amino acid sequence set forth in SEQ ID NO: 69;

(ii) a second HC that comprises or consists of the amino acid sequence set forth in SEQ ID NO: 73; and

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(ii) a second HC that comprises or consists of the amino acid sequence set forth in SEQ ID NO: 72; and

In certain embodiments the first Fc polypeptide comprises a sequence having at least 85%, 90%, or 95% identity to an amino acid sequence selected from the group consisting of SEQ ID NOS: 50 and 70, and the second Fc polypeptide comprises a sequence having at least 85%, 90%, or 95% identity to an amino acid sequence selected from the group consisting of SEQ ID NOS: 39 and 63. In certin embodiments, the first Fc polypeptide comprises a sequence selected from the group consisting of SEQ ID NOS:50 and 70, and the second Fc polypeptide comprises a sequence selected from the group consisting of SEQ ID NO:39 and 63.

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) comprising 1) a VH comprising a sequence having at least 85%, 90%, 95% or 100% identity to any one of SEQ ID NOS:24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO: 50 or 70;

(ii) a second HC comprising 1) a VH comprising a sequence having at least 85%, 90%, 95% or 100% identity to any one of SEQ ID NOS:24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:39 or 63; and (iii) two light chains each independently comprising a VL comprising a sequence having at least 85%, 90%, 95% or 100% identity to any one of SEQ ID NOS:22, 85, 93, 101, and 108.

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:50 (e.g., 100% identity to SEQ ID NO:50);

(ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) second Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:39 (e.g., 100% identity to SEQ ID NO:39); and

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:70 (e.g., 100% identity to SEQ ID NO: 70);

(ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising a sequence having at least 85%, 90%, 95% or 100% identity to SEQ ID NO:63 (e.g., 100% identity to SEQ ID NO:63); and

In certain embodiments:

(a) each VH comprises SEQ ID NO:24 and each VL comprises SEQ ID NO:22;

(b) each VH comprises SEQ ID NO:89 and each VL comprises SEQ ID NO:85;

(c) each VH comprises SEQ ID NO:97 and each VL comprises SEQ ID NO:93;

(d) each VH comprises SEQ ID NO: 105 and each VL comprises SEQ ID NO: 101; or

(e) each VH comprises SEQ ID NO: 112 and each VL comprises SEQ ID NO: 108.

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) that comprises a sequence having at least 90%, 95% or 100% identity to SEQ ID NO: 51 or 71; (ii) a second HC that comprises a sequence having at least 90%, 95% or 100% identity to SEQ ID NO: 53 or 73; and

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) that comprises or consists of the amino acid sequence set forth in SEQ ID NO:51;

In certain embodiments, the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) that comprises or consists of the amino acid sequence set forth in SEQ ID NO:71;

VIII. PHARMACEUTICAL COMPOSITIONS

In certain aspects, an agonist anti-TREM2 antibody may be formulated into a pharmaceutical composition for use in a method as described herein. Thus, in certain methods as described herein, a pharmaceutical composition comprising an agonist anti-TREM2 antibody is administered to a subject.

In some embodiments, the pharmaceutical composition comprises an agonist anti- TREM2 antibody and further comprises one or more pharmaceutically acceptable carriers and/or excipients. A pharmaceutically acceptable carrier includes any solvents, dispersion media, or coatings that are physiologically compatible and that does not interfere with or otherwise inhibit the activity of the active agent. Various pharmaceutically acceptable excipients are well-known in the art.

An anti-TREM2 antibody can be formulated for parenteral administration by injection, e.g., by bolus injection or continuous infusion. IX. EXAMPLES

The present disclosure will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only, and are not intended to limit the disclosure in any manner.

Example 1. Evaluation of the Effects of ATV:TREM2 on Glucose Metabolism

The effects of ATV:TREM2 on microglia function in human iPSC-derived microglia (iMG) and in an AD mouse model were evaluated. In particular, the impact of ATV:TREM2 on glucose metabolism in 5xFAD; hTREM2 tg; TfR^mu/hu was examined as described below.

RESULTS

ATV:TREM2 improved mitochondrial metabolism by promoting glucose oxidation in microglia.

Glucose oxidation was examined in vitro using iMG cells. ATV:TREM2 strongly increased the mitochondrial oxidation of glucose. This activity was blocked by the mitochondrial pyruvate carrier (MPC) inhibitor UK5099 (Fig. 1A, IB). These results suggest that ATV:TREM2 can increase the energetic capacity of microglia by promoting aerobic respiration via glucose catabolism.

To further characterize the effects of ATV:TREM2 on mitochondrial function, mitochondrial membrane potential was assessed with tetramethylrhodamine ethyl ester (TMRE) staining (Fig. 2A). High content imaging showed 72h post ATV:TREM2 treatment, TMRE intensity is increased iMG (data not shown), consistent with increased mitochondria activity. To determine whether mitochondrial structure reflects the functional effects observed with ATV:TREM2, super-resolution microscopy was performed. Morphological analysis showed increased networked mitochondria after ATV:TREM2 treatment (Figs. 2A,2B), which is consistent with an observed boost in microglial respiration. Networked mitochondria have been shown to correlate with increased oxidative phosphorylation and catabolism (Liesa et al., Cell Metab 17, 491-506 (2013); Rambold et al., Trends Immunol 39, 6-18 (2018)).

Based on ATV:TREM2’s ability to boost microglial metabolism in vitro, it was next examined whether this activity could be detected in vivo. RNA sequencing was performed on microglia isolated from hTREM2 tg; TfR^mu/hu mice dosed with lOmg/kg ATV:TREM2, ATVTSO, or vehicle control. Brain microglia were isolated 1, 4, and 7 days post dose. A significant transcriptional response was observed at 1 day compared to isotype and vehicle treated controls, which was largely attenuated 4 and 7 days post dose (Fig. 2C). Strikingly, ATV:TREM2 robustly increased oxidative phosphorylation and glycolysis pathway genes (Fig. 2D), consistent with increased mitochondrial respiration and glucose metabolism in iMG.

ATV:TREM2 increases brain microglial activity in an AD model

To investigate the functional effects of ATV:TREM2 using clinically translatable imaging techniques with potential relevance to the TREM2 pathway biology described above, the hTREM2 tg; TfR^mu/hu mice were crossed to the 5xFAD model (Oakley, H., et al. J Neurosci 26, 10129-10140 (2006)) and these mice were used to monitor brain microglial activity by [¹⁸F]GE- 180 18kDa translocator protein positron emission-tomography (TSPO-PET). Increased mitochondrial TSPO expression is associated with responsive microglia (Xiang, X., et al., Sci Transl Med 13, eabe5640 (2021)), and TREM2 LOF brains exhibit lower TSPO-PET signal compared to wild type controls (Kleinberger, EMBO J, 36, 1837-1853 (2017); Gotzl et al., EMBO Mol Med 1 l(6):e9711, (2019)). Therefore, it was hypothesized TSPO-PET imaging could be a relevant indicator of ATV:TREM2 function in vivo. TSPO-PET signal was assessed longitudinally in 5xFAD; hTREM2 tg; TfR^mu/hu and WT; hTREM2 tg; TfR^mu/hu mice dosed with ATV:TREM2 and an isotype control at 1, 4 and 8 days post dose. ATV:TREM2 increased the cortical TSPO- PET signal in 5xFAD; hTREM2 tg; TfR^mu/hu progressively with significant differences at day 8 compared to an isotype control (dl : +8%, d4: +19%, d8: +24%,) (Fig. 3 A,B). TSPO signal in WT; hTREM2 tg; TfR^mu/hu mice was detected at a lower baseline compared to 5xFAD. In wild type mice lacking amyloid pathology, ATV:TREM2 treatment resulted in a small, yet statistically significant increase in TSPO signal intensity at day 8 compared to the isotype treated control group (dl : +1%, d4: +6%, d8: +14%) (Fig. 3A,C). These results show ATV:TREM2 increased mitochondrial TSPO selectively in an amyloid model, indicating elevated microglial activity.

ATV:TREM2 increases brain glucose metabolism in an AD model

As discussed above, hTREM2 tg; TfR.^mu/hu mice were crossed to the 5xFAD model (Oakley, H., et al. J Neurosci 26, 10129-10140 (2006)) and then used to evaluate brain glucose metabolism. Specifically, cortical 2-deoxy-2[¹⁸F]fluoro-d-glucose (FDG)-PET imaging was performed in 5xFAD; hTREM2-tg; TfR.^mu/humice dosed with ATV:TREM2 or an isotype control over 8 days. FDG-PET signal was increased upon ATV:TREM2 treatment compared to isotype control (dl : +15%, d4: +19%, d8: +27%) (Fig. 3D-3F). There was no treatment effect in WT; hTREM2 tg; TfR^mu/hu mice (dl : -5%, d4: -3%, d8: -3%) (Fig. 3D, 3F). [18F]florbetaben beta- amyloid-PET in 5xFAD; hTREM2 tg; TfR.^m'^l/h" mice was also performed to determine if regional amyloid load correlated with ATV:TREM2 effects on TSPO- and FDG-PET. There was significant regional association for TSPO- and FDG-PET at day 8 with FBB signal, suggesting the presence of beta-amyloid impacts ATV:TREM2 effects (Fig. 3G,3H). Notably, while AD mouse models do not recapitulate glucose hypometabolism observed in AD patients, these results suggest ATV:TREM2 could improve brain glucose metabolism, thereby ameliorating this metabolic deficit in human disease.

MATERIALS AND METHODS

Generation of recombinant antibodies

To generate ATV:TREM2 the Fc domain was replaced on the anti-TREM2 antibody with the engineered Fc sequence (Kariolis et al., Sci Transl Med. (2020) 12(545):eaayl359) with the effector knock-out substitutions. Additionally, the sequence encoding the Fc polypeptide engineered to bind TfR also contained a “knob” (T366W) mutation; and the sequence encoding the other Fc polypeptide that lacked TfR binding mutations comprised “hole” (T366S/L368A/Y407V) mutations. These coding sequences also contained “LS” (M428L; N434S) mutations. Specifically, the sequences for ATV:TREM2 were: heavy chain 1 : SEQ ID NO:48 or 69; heavy chain 2: SEQ ID NO:53 or 73, and light chain: SEQ ID NO:54

The heavy chains of ATV:TREM2 may be further processed during cell culture production, such that the C-terminal Lys residue is removed (i.e., the Lys residue at position 447, according to the EU numbering scheme). For example, as used herein, the term ATV:TREM2 may be used to refer to antibodies having unprocessed sequences (i.e., SEQ ID NOs:48 and 53); antibodies comprising one or more processed sequences (i.e., selected from SEQ ID NOs: 69 and 73); or to a composition comprising a mixture of processed and unprocessed antibodies.

Expression and purification of antibodies

ATV:TREM2 and an isotype control were expressed via transient transfection of Expi293 cell line (Thermo Fisher Scientific) adapted to BalanCD HEK293 media (Irvine Scientific) according to manufacturer’s instructions. Cultures were co-transfected with plasmids encoding for standard monoclonal antibody (2-chain): 1 : 1 Heavy Chain (HC):Light Chain (LC); and antibody transport vehicle (ATV) molecule: 1 : 1:2 Knob:Hole:Light Chain (LC).

ATV:TREM2 and an isotype control were purified to homogeneity from serum-free BCD293 cultures by a series of chromatographic steps. Supernatants were loaded onto a lx PBS equilibrated HiTrap MabSelect PrismA affinity column (Cytiva using an Akta Pure System), the column was then washed with 5 column volumes (CVs) of lx PBS and 0.1% Triton X-100, followed by 10CV of lx PBS wash. Bound proteins were eluted using 0. IM sodium citrate pH3.6 and 150mM sodium chloride. Immediately after elution, Protein A eluate was neutralized to pH6.5 with IM Tris pH8. Neutralized Protein A eluate was conditioned with 50mM sodium acetate pH6.5 prior cation-exchange chromatography. A linear gradient with, 0.5M sodium chloride and 50mM sodium acetate pH6.5 was used to elute proteins from SP HP resin (Cytiva). Final fractions with a high degree of purity, as assessed by analytical size-exclusion chromatography (SEC) and/or microcapillary electrophoresis (Caliper), were pooled, concentrated and dialyzed into formulation buffer of lOmM sodium acetate pH5.5, 6% sucrose and/or lx PBS for cell-based functional assay. Preparations were stored at 4°C or -80°C prior to use and routinely analyzed by SEC, SPR and for endotoxin content.

Generation and cell culture of human iPSC-derived microglia

Hematopoietic Differentiation

Human iPSCs were maintained in mTESR-Plus (Stemcell Technologies #100-0276) until seeding for differentiation. When cells reached -80% confluence they were singularized with TrypLE Express (ThermoFisher #12604013) for five minutes, mechanically dissociated with a Pl 000 tip using mTeSR-Plus and transferred to a 15mL conical tube, and pelleted at 300xg for five minutes. Cells were resuspended in mTeSR-Plus and counted using a Nexcelom cellometer and seeded into mTeSR-Plus + lOuM y-27632 (Tocris #1254) at 13,200 cells/cm² (approximately 50,000 cells per well of a 12-well tissue culture plate). All media used for hematopoietic differentiation was from Stemcell Technologies STEMdiff Hematopoietic Kit (#05310). On Day 0, mTeSR-Plus+y-27632 was aspirated and replaced with l.OmL medium A. On Day 2, 0.5mL medium A was removed from each well and 0.5mL fresh medium A was added. On Day 3, all medium A was removed from each well and fresh medium B was added. On Day 3, primary human astrocyte feeder cells were thawed and seeded into poly-L-Lysine coated 10cm² tissue culture dishes using Lonza AGM (CC-3186) as growth medium. This was done so cells would be ready to serve as feeder cells by Day 12. On Days 5 and 7, 0.5mL medium B was removed from each well and 0.5mL fresh medium B was added back to the well. On Day 8, primary human astrocytes were dissociated using 0.05% Trypsin-EDTA (ThermoFisher, 25300062), counted in the Nexcelom cellometer and seeded at 10,000 cells/cm² (approximately 100,000 cells per well of a 6-well tissue culture plate was used). On Day 9, no medium was removed, but 0.5mL medium B was added to each well. On Day 10, floating colonies of hematopoietic progenitor cells (HPCs) were visible and collected. To collect the cells, medium from each well was collected and added to a 15mL conical tube. Cells were briefly mechanically dissociated with a serological pipet and tubes were transferred to the centrifuge and pelleted at 300xg for five minutes. 0.5mL fresh medium B was added to each well of the 12-well plate. After pelleting HPCs, 0.5mL of conditioned medium from each tube was added back to each well of the 12-well plate and the plate was returned to the incubator. Any remaining medium in the conical tube was then aspirated and HPCs were resuspended in microglia differentiation medium (IMDM base medium containing 10% FBS, and 20ng/mL each of GM-CSF (Peprotech, AF-300-03), IL3 (Peprotech, AF-200-03), and M-CSF (Peprotech, AF-30-25)). AGM was aspirated from the astrocyte feeder cell plates and HPCs collected from an entire 12-well plate were seeded evenly across 2, 6-well plates containing astrocyte feeder cells (bring total microglia differentiation medium volume to 2mL/well). On Day 12, the same steps from Day 10 were repeated and the cells were seeded evenly across the same 6-well plates already containing HPCs and astrocyte feeder cells (each well then contained 4mL/well). After one week of culture numerous cells are seen proliferating in suspension with some firmly attaching to astrocyte feeder cells. Note-. A small fraction of HPCs was collected at Day 10 and Day 12 to ensure that at least 80% of cells are CD43⁺ by flow cytometry analysis.

Microglia Differentiation and Maintenance

On Day 20, 2mL medium was collected from each well and suspension cells were pelleted at 300xg for five minutes. Medium was aspirated and pelleted cells were resuspended in 24mL microglia differentiation medium (see above) and 2mL of the cell suspension was added back to each well. This process was repeated ~ every 5 days as needed to maintain a consistent pH in the medium (phenol red indicated). By Day 42 cells were harvested and seeded in an assay dependent manner.

Seahorse detection of cellular respiration iMG (20,000 cells/well) were seeded on PDL-coated 96-well Agilent Seahorse XF Cell Culture microplate in microglia differentiation media. For glucose oxidation measurements, cells were kept in microglia differentiation media. Antibody (either ATV:TREM2 or ATV:ISO) was then added to the cells to a final concentration of lOOnM and incubated for three days. On the day of the assay, cells were washed twice with assay media comprised of lOmM glucose, 2mM glutamine, and ImM pyruvate. Antibody was re-added to the washed cells to a final concentration of lOOnM. Cells were imaged using brightfield microscopy to obtain cell counts utilized for normalization. Cells were then incubated for 1 hour in a non-CO2 incubator before beginning the Seahorse experiment. Ports on the sensor plate were filled according to the XF Glucose Oxidation Kit, and cells were subjected to sequential injections of oligomycin (final concentration 1.5uM), FCCP (2-[2-[4-(trifluoromethoxy)phenyl]hydrazinylidene]-propanedinitrile) (1.5uM for glucose oxidation), and rotenone/antimycin A (0.5uM each). In experiments using an inhibitor UK5099 was added in port A at 3uM final concentration. Data was analyzed using the Agilent Seahorse Analytics online software to generate kinetic curves and calculate maximal respiration and spare capacity.

Super-resolution microscopy and quantification of TMRE-stained iMG dosed with ATV:TREM2 iMG (20,000 cells/well) were seeded on PDL-coated 96-well Agilent Seahorse XF Cell Culture microplate in microglia differentiation media. After 24h, media was changed to fresh microglia differentiation media containing lOOnM ATV:TREM2 or ATV:ISO. Cells were incubated for 3 days, then media was removed and replaced with Live Cell Imaging Solution (Invitrogen A14291) containing lOnM TMRE (Abeam abl 13852) for 20 min. Cells were then washed once with Live Cell Imaging Solution, then imaged with a laser scanning confocal microscope (Leica SP8; Leica Microsystems, Inc), acquired with a 40x/1.3 NA oil objective in LIGHTNING super-resolution mode at a pixel size of 36 nm and images were processed using an adaptive processing algorithm. The representative images were generated by three-dimensional reconstruction in Imaris (Bitplane). To identify different classes of mitochondrial morphology, individual mitochondrial surfaces were segmented by thresholding on the TMRE fluorescence intensity. Morphological classes were defined by using object volume and the long axis of the object-oriented bounding box and assigning classes for punctate, elongated and networked mitochondria.

To calculate the effects of ATV:TREM2 on TMRE intensity, cells were also co-incubated with NucBlue (1 drop / mL) during the TMRE incubation, and cells were washed once with Live Cell Imaging Solution and imaged using high-content microscopy (Opera Phoenix) to obtain intensity measurements per cell on 3000-4000 cells per experimental replicate.

Transcriptional responses in isolated microglia after ATV:TREM2 treatment

Sample Preparation

Human TREM2 tg; TfR^mu/hu KI mice were dosed with ATV:TREM2 or ATVTSO at 10 mg/kg and sacrificed 1, 4, 7 days post dose (n=8 mice per group). Brains were dissected out after PBS perfusion for single cell dissociation by the Adult Brain Dissociation Kit (Miltenyi Biotec, 130-107-677), according to the manufacturer’s protocol. The single cell suspensions were enriched for immune cells via MACS sorting with Miltenyi CD45 microbeads, mouse (130-052- 301) per manufacturer's protocol. Single cell suspensions were prepared in 3 batches, each batch containing one sample of each experimental group. Sorted cells were subjected to bulk RNA sequencing.

Bulk RNA-seq library preparation

Bulk RNA-seq libraries were generated using QuantSeq 3‘ mRNA-seq Library Prep Kit FWD for Illumina (Lexogen AO 1173) with the UMI second strand synthesis module in order to identify and remove PCR duplicates, following the protocol defined by the manufacturer. Library quantity and quality were assessed with Qubit™ IX dsDNA HS Assay Kits (Invitrogen Q33231) and Bioanalyzer High Sense DNA chip (Agilent 5067-4626). Libraries were combined in equimolar ratios into one sequencing pool. Next-generation sequencing of 75 bp, single end reads were generated on an Illumina NovaSeq instrument with a SP flow cell at SeqMatic (Fremont, CA).

Bulk RNA-seq data processing and analysis

Raw FASTQ files were aligned to the genome using the STAR aligner (Dobin, A., et al. Bioinformatics 29, 15-21 (2013) and summarized into gene-level counts \ism featureCounts from the subread package (Liao, et al., Bioinformatics 30, 923-930 (2014)) as previously described (Nugent, et al., Neuron 105, 837-854 e839 (2020)). Lowly expressed and non protein-coding genes were removed, and differential expression analysis was performed using the limma/voom pipeline (Law, et al., Genome Biol 15, R29 (2014). Linear models were constructed to identify genes differentially expressed between the groups of interest. “Takedown day” was encoded as a fixed effect to account for potential technical artifacts induced by processing animals on different days. Gene set enrichment analysis (GSEA) was used to summarize individual differential gene expression results at the pathway/ signature level (Korotkevich, G., etal. bioRxiv, 060012 (2021)). Gene sets were taken from the hallmark molecular signature database (Liberzon, A., et al. Cell Syst 1, 417-425 (2015)). GSEA statistics were generated using the fgseaMultiLevel function in the fgsea R package using the moderated t-statistic as the gene ranking statistic (Korotkevich, G., et al. bioRxiv, 060012 (2021)). All software versions for the RNA-seq analysis correspond to Bioconductor release version 3.13 (Huber, W ., etal. Nat Methods 12, 115-121 (2015)). Individual genes were selected to show pathway activity in the Figure 2D heatmaps by extracting the top 10- 20 genes found in the “leading edge” of each pathway when ranked by their individual t-statistics. Generation of human Trem2 BAC transgenic mouse model

Human Trem2 BAC transgenic (tg) mouse model was used to evaluate the human specific ATV:TREM2 antibody in vivo. This mouse model was generated by introduction of engineered BAC DNA CTD-2210D2 into the pronucleus of fertilized mouse eggs from C57BL/6J mice. The engineered BAC DNA CTD-2210D2 clone covers the entire human Trem2 coding region and its regulatory elements with deletion of the exon 1 from TREML1 and exon 3 from TREML2 to abolish the expression of TREML1 and TREML2. Human Trem2 BAC tg mice were backcrossed to C57BL/6J mice for three rounds and maintained as hemizygous and then further bred with hTfR-KI mice to generate human TREM2 BAC tg; hTfR KI mice for in vivo studies. Animals were housed in standard conditions with ad libitum access to food and water.

PET Imaging study design, antibody dosing and perfusion of mice

On day 0, 5-6mo old WT; hTREM2 tg; TfR^mu/humice and 4.5mo old 5xFAD; hTREM2 tg; TfR^mu/humice were injected intraperitoneally with ATV:TREM2 and an isotype control antibody at 14mg/kg and lOmg/kg, respectively. 24h after antibody dosing mice were subjected to either TSPO-PET or FDG-PET imaging, i.e., separate cohorts of mice were used for TSPO-PET and FDG-PET imaging. Microglia activation and brain glucose metabolism were followed longitudinally with further PET scans on days 4 and 8 after antibody administration. Male and female mice were distributed evenly among both antibody treatment and PET imaging groups.

Small animal PET/MRI

All rodent PET procedures followed an established standardized protocol for radiochemistry, acquisition times and post-processing, which was transferred to a novel PET/MRI system. All mice were scanned with a 3T Mediso nanoScan PET/MR scanner (Mediso Ltd, Hungary) with a triple-mouse imaging chamber. Two 2-minute anatomical T1 MR scans were performed prior to tracer injection (head receive coil, matrix size 96 x 96 x 22, voxel size 0.24 x 0.24 x 0.80 mm³, repetition time 677 ms, echo time 28.56 ms, flip angle 90°). Injected dose was 12.3 +/- 2.2 MBq for [¹⁸F]GE-180 (TSPO) and 14.5 +/- 3.4 MBq [¹⁸F]FDG (glucose) delivered in 200 pl saline via venous injection. PET emission was recorded in a dynamic 0-90 min window for TSPO PET and in a dynamic 0-60 min window for FDG PET. List-mode data within 400-600 keV energy window were reconstructed using a 3D iterative algorithm (Tera-Tomo 3D, Mediso Ltd, Hungary) with the following parameters: matrix size 55 x 62 x 187 mm³, voxel size 0.3 x 0.3 x 0.3 mm³, 8 iterations, 6 subsets. Decay, random, and attenuation correction were applied. The T1 image was used to create a body-air material map for the attenuation correction. PET images of WT; hTREM2 tg; TfR^mu/hu mice and 5xFAD; hTREM2 tg; TfR^mu/hu mice (n=6 per antibody and placebo group) were studied. Framing was 6x10s, 6x30s, 6x60s, 10x300s for FDG-PET and 6x10, 2x30, 3x60, 5x120, 5x300, 5x600 for TSPO-PET. Normalization of TSPO PET data was performed by the previously validated myocardium correction method for the previously established 60-90 min time window, after cross validation against volume of distribution (VT) images obtained from the full dynamic scan. VT images were generated with an image derived input function (Xiang, X., et al., Sci Transl Med 13, eabe5640 (2021); Schiffer, et al., J NuclMed 48, 277-287 (2007)) using a methodology as previously described (Logan, J., et al. J Cereb Blood Flow Metab 10, 740-747 (1990)). The plasma curve was obtained from a standardized bilateral VOI placed in both carotid arteries. A maximum error of 10% and a VT threshold of 0 were selected for modelling of the full dynamic imaging data. Late static myocardium corrected TSPO-PET data were used and reported due to less methodological variance, which was proven to be beneficial in serial small animal PET imaging (PMID 28988133). Normalization of FDG-PET was performed by standardized uptake values (SUVs), reflecting the common read-out in clinical setting. Blood-flow adjusted validation of FDG-PET quantification was performed by a simplified reference tissue modelling approach, using the periaqueductal grey as an established reference tissue (PMID 31302633). The reference tissue was validated by analyzing antibody and vehicle injected mice using VT images as described above which confirmed no VT differences between study groups between groups in the periaqueductal grey. A predefined forebrain volume-of-interest (comprising 19.4 mm³) was delineated by cortical, striatal and hippocampal regions of the Mirrione atlas and served for extraction of TSPO- PET and FDG-PET values for all mice.

Example 2. Evaluation of the Effects of ATV:TREM2 on GLUT1 Expression in iP SC Microglia

The glucose transporter type 1 (GLUT1) protein, also known as solute carrier family 2, facilitated glucose transporter member 1, is a predominant glucose transporter expressed in microglia. As described below, the effects of ATV:TREM2 on GLUT1 protein expression in human iPSC-derived microglia were evaluated.

Results

GLUT1 surface levels were increased in iPSC microglia after treatment with ATV:TREM2, as compared to an isotype control (ATVTSO). In contrast, total GLUT1 levels were unchanged, suggesting GLUT1 mobilizes to the cell surface upon ATV:TREM2 treatment. These results suggest treatment with ATV:TREM2 increases glucose metabolism by increasing glucose uptake via the modulation of GLUT1 surface levels.

Materials and Methods

Generation, expression and purification of antibodies

ATV:TREM2 and an isotype control (ATV:ISO) were generated, expressed, and purified as described in Example 1.

Generation and cell culture of human iPSC-derived microglia

Human iPSC-derived microglia were generated and cultured using methods similar to those described in Example 1.

Measurement of Surface Expression Levels of GLUT1 iPSC microglia were plated on a 96-well plates (Phenoplates, Perkin Elmer) and allowed to adhere for 24h in IMDM (Gibco) containing 10% FBS (Gibco), 1% pen/strep (Gibco), 20ng/mL hM-CSF, 20ng/mL hGM-CSF (Peprotech), and 20ng/mL hIL3 (Peprotech). Cells were then treated for 96h with lOOnM antibody, then the cells were stained live at 4°C with 1 : 100 GLUT1-PE antibody (EPR3915, Abeam) in PBS containing 0.5% BSA and 2mM EDTA for 30min. Cells were fixed with 4% paraformaldehyde in PBS, stained with 1 : 1000 DAPI (Thermo Fisher), then washed twice with PBS. The plate was imaged using OperaPhoenix (Perkin Elmer) high content imager at 40x, and PE intensity determined in the 568 channel using the spot-finding algorithm (Harmony software, Perkin Elmer).

Measurement of Total Expression Levels of GLUT1

To measure total levels of GLUT1, cells were treated with antibody as described above, but fixed and permeabilized prior to GLUT1-PE staining. Cells were permeabilized for 30min in PBS containing 5% BSA and 0.05% saponin, then stained with 1 : 100 GLUT1-PE antibody overnight in PBS containing 1% BSA and 0.01% saponin. Table 2. Informal Sequence Listing

All publications, patents, and patent documents are incorporated by reference herein, as though individually incorporated by reference. The present disclosure has been described with reference to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. A method for treating brain glucose hypometabolism in a subject in need thereof, comprising administering to the subject an effective amount of an agonist anti -triggering receptor expressed on myeloid cells 2 (TREM2) antibody.

2. The method of claim 1, wherein the administration increases brain glucose metabolism in the subject by at least 10% as compared to a control value.

3. The method of claim 1 or 2, wherein the administration increases microglial glucose metabolism in the subject by at least about 10% as compared to a control value.

4. The method of any one of claims 1-3, wherein the administration increases glucose uptake by a brain cell in the subject as compared to a control value.

5. The method of claim 4, wherein the administration increases glucose uptake by a brain cell in the subject by at least about 10% as compared to a control value.

6. The method of any one of claims 1-5, wherein the administration increases glucose oxidation in a brain cell in the subject as compared to a control value.

7. The method of claim 6, wherein the administration increases glucose oxidation in a brain cell in the subject by at least about 10% as compared to a control value.

8. The method of any one of claims 4-7, wherein the brain cell is a microglial cell.

9. The method of any one of claims 1-8, wherein the subject has, or is prone to developing, a neurodegenerative disease.

10. The method of claim 9, wherein the neurodegenerative disease is selected from the group consisting of Alzheimer’s disease, primary age-related tauopathy, progressive supranuclear palsy (PSP), frontotemporal dementia, frontotemporal dementia with parkinsonism linked to chromosome 17, argyrophilic grain dementia, amyotrophic lateral sclerosis, amyotrophic lateral sclerosis/parkinsonism-dementia complex of Guam (ALS-PDC), corticobasal degeneration, chronic traumatic encephalopathy, Creutzfeldt-Jakob disease, dementia pugilistica, diffuse neurofibrillary tangles with calcification, Down’s syndrome, familial British dementia, familial Danish dementia, Gerstmann-Straussler-Scheinker disease, globular glial tauopathy, Guadeloupean parkinsonism with dementia, Guadelopean PSP, Hallevorden-Spatz disease, hereditary diffuse leukoencephalopathy with spheroids (HDLS), Huntington’s disease, inclusionbody myositis, multiple system atrophy, myotonic dystrophy, Nasu-Hakola disease, neurofibrillary tangle-predominant dementia, Niemann-Pick disease type C, pallido-ponto-nigral degeneration, Parkinson’s disease, Pick’s disease, postencephalitic parkinsonism, prion protein cerebral amyloid angiopathy, progressive subcortical gliosis, subacute sclerosing panencephalitis, adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP), epilepsy and tangle only dementia.

11. The method of claim 10, wherein the neurodegenerative disease is Alzheimer’s disease.

12. An agonist anti-TREM2 antibody for use in treating brain glucose hypometabolism in a subject in need thereof.

13. The use of an agonist anti-TREM2 antibody in the preparation of a medicament for treating brain glucose hypometabolism in a subject in need thereof.

14. A method for treating a neurodegenerative disease in a subject having brain glucose hypometabolism, the method comprising administering to the subject an effective amount of an agonist anti-TREM2 antibody.

15. The method of claim 14, wherein the neurodegenerative disease is selected from the group consisting of Alzheimer’s disease, primary age-related tauopathy, progressive supranuclear palsy (PSP), frontotemporal dementia, frontotemporal dementia with parkinsonism linked to chromosome 17, argyrophilic grain dementia, amyotrophic lateral sclerosis, amyotrophic lateral sclerosis/parkinsonism-dementia complex of Guam (ALS-PDC), corticobasal degeneration, chronic traumatic encephalopathy, Creutzfeldt-Jakob disease, dementia pugilistica, diffuse neurofibrillary tangles with calcification, Down’s syndrome, familial British dementia, familial Danish dementia, Gerstmann-Straussler-Scheinker disease, globular glial tauopathy, Guadeloupean parkinsonism with dementia, Guadelopean PSP, Hallevorden-Spatz disease, hereditary diffuse leukoencephalopathy with spheroids (HDLS), Huntington’s disease, inclusion- body myositis, multiple system atrophy, myotonic dystrophy, Nasu-Hakola disease, neurofibrillary tangle-predominant dementia, Niemann-Pick disease type C, pallido-ponto-nigral degeneration, Parkinson’s disease, Pick’s disease, postencephalitic parkinsonism, prion protein cerebral amyloid angiopathy, progressive subcortical gliosis, subacute sclerosing panencephalitis, adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP), epilepsy and tangle only dementia.

16. The method of claim 15, wherein the neurodegenerative disease is Alzheimer’s disease.

17. The method of any one of claims 14-16, wherein the administration increases brain glucose metabolism in the subject by at least about 10% as compared to a control value.

18. The method of any one of claims 14-17, wherein the administration increases microglial glucose metabolism in the subject by at least about 10% as compared to a control value.

19. An agonist anti-TREM2 antibody for use in treating a neurodegenerative disease in a subject having brain glucose hypometabolism.

20. The use of an agonist anti-TREM2 antibody in the preparation of a medicament for treating a neurodegenerative disease in a subject having brain glucose hypometabolism.

21. A method of increasing glucose metabolism, glucose uptake and/or glucose oxidation in a TREM2 expressing cell, comprising contacting the cell with an effective amount of an agonist anti-TREM2 antibody.

22. The method of claim 21, wherein the cell is a microglial cell.

23. The method of claim 21 or 22, wherein glucose metabolism in the cell is increased by at least about 10% as compared to a control value.

24. The method of any one of claims 21-23, wherein glucose uptake by the cell is increased by at least about 10% as compared to a control value.

25. The method of claim of any one of claims 21-24, wherein glucose oxidation in the cell is increased by at least about 10% as compared to a control value.

26. The method of any one of claims 21-25, wherein the cell is contacted in vitro.

27. The method of any one of claims 21-25, wherein the cell is present in a subject and is contacted in vivo.

28. An agonist anti-TREM2 antibody for use in increasing glucose metabolism, glucose uptake and/or glucose oxidation in a TREM2 expressing cell.

29. The use of an agonist anti-TREM2 antibody in the preparation of a medicament for increasing glucose metabolism, glucose uptake and/or glucose oxidation in a TREM2 expressing cell.

30. A method of selecting a subject having a neurodegenerative disease for treatment with an agonist anti-TREM2 antibody, the method comprising evaluating the subject’s brain glucose metabolism levels and selecting the subject for treatment when the levels are less than a control value.

31. The method of claim 30, further comprising administering an agonist anti-TREM2 antibody to the subject.

32. The method of claim 30 or 31, wherein the neurodegenerative disease is Alzheimer’s disease.

33. The method of any one of claims 1-32, wherein the agonist anti-TREM2 antibody comprises: i. a CDR-H1 sequence comprising the sequence of G-F-T-F-T-ae-F-Y-M-S (SEQ ID NO:28), wherein ae is D or N; ii. a CDR-H2 sequence comprising the sequence of V-I-R-N-Ps-Pe-N-Ps-Y- T-P11-P12-Y-N-P-S-V-K-G (SEQ ID NO:29), wherein p₅ is K or R; p₆ is A or P; p₈ is A or G; Pn is A or T; and P12 is G or D; iii. a CDR-H3 sequence comprising the sequence of yi-R-L-y4-Y-G-F-D-Y (SEQ ID NO:30), wherein yi is A or T; and i is T or S; iv. a CDR-L1 sequence comprising the sequence of Q-S-S-K-S-L-L-H-S-610- G-K-T-Y-L-N (SEQ ID NO:31), wherein 5io is T or N; v. a CDR-L2 sequence comprising the sequence of WMSTRAS (SEQ ID NO:8); and vi. a CDR-L3 sequence comprising the sequence of Q-Q-F-L-E-<|)6-P-F-T (SEQ ID NO:32), wherein <|>6 is Y or F.

34. The method of claim 33, wherein the CDR-H1 sequence is SEQ ID NO:4 or 12.

35. The method of claim 33 or 34, wherein the CDR-H2 sequence is SEQ ID NO:25, 5, or 13.

36. The method of any one of claims 33-35, wherein the CDR-H3 sequence is SEQ ID NO: 17, 6, or 14.

37. The method of any one of claims 33-36, wherein the CDR-L1 sequence is SEQ ID NO:23 or 7.

38. The method of any one of claims 33-37, wherein the CDR-L3 sequence is SEQ ID NO: 18 or 9.

39. The method of any one of claims 33-38, wherein the agonist anti-TREM2 antibody comprises:

(a) a CDR-H1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 17, a CDR-L1 comprising the amino acid sequence of SEQ ID NO:23, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 18; or

(b) a CDR-H1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:5, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 17, a CDR-L1 comprising the amino acid sequence of SEQ ID NO:7, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 18; or (c) a CDR-H1 comprising the amino acid sequence of SEQ ID NON, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:5, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 17, a CDR-L1 comprising the amino acid sequence of SEQ ID NO:23, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 18; or

(d) a CDR-H1 comprising the amino acid sequence of SEQ ID NON, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 17, a CDR-L1 comprising the amino acid sequence of SEQ ID NO:7, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 18; or

(e) a CDR-H1 comprising the amino acid sequence of SEQ ID NON, a CDR-H2 comprising the amino acid sequence of SEQ ID NON, a CDR-H3 comprising the amino acid sequence of SEQ ID NO:6, a CDR-L1 comprising the amino acid sequence of SEQ ID NON, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 9; or

(f) a CDR-H1 comprising the amino acid sequence of SEQ ID NO: 12, a CDR-H2 comprising the amino acid sequence of SEQ ID NO: 13, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 14, a CDR-L1 comprising the amino acid sequence of SEQ ID NON, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NON; or

(g) a CDR-H1 comprising the amino acid sequence of SEQ ID NON, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 17, a CDR-L1 comprising the amino acid sequence of SEQ ID NON, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:8, and a CDR-L3 comprising the amino acid sequence of SEQ ID NON.

40. The method of any one of claims 33-39, wherein the the agonist anti-TREM2 antibody comprises a VH sequence comprising a sequence that has at least 85% sequence identity to any one of SEQ ID NOS :24, 2, 10, 15, 19, 21, and 26.

41. The method of claim 40, wherein the VH sequence comprises a sequence that has at least 90% or 95% sequence identity to SEQ ID NO:24.

42. The method of claim 41, wherein the VH sequence comprises SEQ ID NO:24.

43. The method of claim 40, wherein the VH sequence comprises a sequence that has at least 90% or 95% sequence identity to SEQ ID NO: 15.

44. The method of claim 43, wherein the VH sequence comprises SEQ ID NO: 15.

45. The method of any one of claims 33-44, wherein the agonist anti-TREM2 antibody comprises a VL sequence comprising a sequence that has at least 85% sequence identity to any one of SEQ ID NOS:22, 3, 11, 16, 20, and 27.

46. The method of claim 45, wherein the VL sequence comprises a sequence that has at least 90% or 95% sequence identity to SEQ ID NO:22.

47. The method of claim 46, wherein the VL sequence comprises SEQ ID NO:22.

48. The method of claim 45, wherein the VL sequence comprises a sequence that has at least 90% or 95% sequence identity to SEQ ID NO: 16.

49. The method of claim 48, wherein the VL sequence comprises SEQ ID NO: 16.

50. The method of claim 45, wherein the VL sequence comprises a sequence that has at least 90% or 95% sequence identity to SEQ ID NO:27.

51. The method of claim 50, wherein the VL sequence comprises SEQ ID NO:27.

52. The method of any one of claims 33-51, wherein the agonist anti-TREM2 antibody comprises:

(a) a VH sequence comprising SEQ ID NO:24 and a VL sequence comprising SEQ ID NO:22; or

(b) a VH sequence comprising SEQ ID NO: 15 and a VL sequence comprising SEQ ID NO: 16; or

(c) a VH sequence comprising SEQ ID NO: 19 and a VL sequence comprising SEQ ID NO:20; or (d) a VH sequence comprising SEQ ID NO:21 and a VL sequence comprising SEQ ID NO:20; or

(e) a VH sequence comprising SEQ ID NO: 19 and a VL sequence comprising SEQ ID NO:22; or

(f) a VH sequence comprising SEQ ID NO:21 and a VL sequence comprising SEQ ID NO:22; or

(g) a VH sequence comprising SEQ ID NO:24 and a VL sequence comprising SEQ ID NO:20; or

(h) a VH sequence comprising SEQ ID NO:26 and a VL sequence comprising SEQ ID NO:20; or

(i) a VH sequence comprising SEQ ID NO:26 and a VL sequence comprising SEQ ID NO:22; or

(j) a VH sequence comprising SEQ ID NO:2 and a VL sequence comprising SEQ ID NO:3; or

(k) a VH sequence comprising SEQ ID NO: 10 and a VL sequence comprising SEQ ID NO: 11; or

(l) a VH sequence comprising SEQ ID NO:24 and a VL sequence comprising SEQ ID

NO:27.

53. The method of any one of claims 1-32, wherein the agonist anti-TREM2 antibody comprises: i. a CDR-H1 sequence comprising the sequence of SYWIG (SEQ ID NO: 90); ii. a CDR-H2 sequence comprising the sequence of HYPGDADARYSPSFQG (SEQ ID N0:91); iii. a CDR-H3 sequence comprising the sequence of RRQGIFGDALDF (SEQ ID NO: 92); iv. a CDR-L1 sequence comprising the sequence of RASQSVSSNLA (SEQ ID NO:86); v. a CDR-L2 sequence comprising the sequence of GASTRAT (SEQ ID NO: 87); and vi. a CDR-L3 sequence comprising the sequence of LQDNNFPPT (SEQ ID NO:88).

54. The method of claim 53, wherein the agonist anti-TREM2 antibody comprises a VH sequence comprising a sequence that has at least 85%, 90%, or 95% sequence identity to SEQ ID NO:89.

55. The method of claim 54, wherein the VH sequence comprises SEQ ID NO:89.

56. The method of any one of claims 53-55, wherein the agonist anti-TREM2 antibody comprises a VL sequence comprising a sequence that has at least 85%, 90%, or 95% sequence identity to SEQ ID NO: 85.

57. The method of claim 56, wherein the VL sequence comprises SEQ ID NO:85.

58. The method of any one of claims 53-57, wherein the agonist anti-TREM2 antibody comprises a VH sequence comprising SEQ ID NO:89 and a VL sequence comprising SEQ ID NO:85.

59. The method of any one of claims 1-32, wherein the agonist anti-TREM2 antibody comprises: i. a CDR-H1 sequence comprising the sequence of NYWIA (SEQ ID NO:98); ii. a CDR-H2 sequence comprising the sequence of IIYPGDSDTRYSPSFQG (SEQ ID NO: 99); iii. a CDR-H3 sequence comprising the sequence of QRTFYYDSSGYFDY (SEQ ID NO: 100); iv. a CDR-L1 sequence comprising the sequence of RASQGISNWLA (SEQ ID NO: 94); v. a CDR-L2 sequence comprising the sequence of AASSLQV (SEQ ID NO:95); and vi. a CDR-L3 sequence comprising the sequence of QQADSFPRN (SEQ ID NO:96).

60. The method of claim 59, wherein the agonist anti-TREM2 antibody comprises a VH sequence comprising a sequence that has at least 85%, 90%, or 95% sequence identity to SEQ ID NO:97.

61. The method of claim 60, wherein the VH sequence comprises SEQ ID NO:97.

62. The method of any one of claims 59-61, wherein the agonist anti-TREM2 antibody comprises a VL sequence comprising a sequence that has at least 85%, 90%, or 95% sequence identity to SEQ ID NO: 93.

63. The method of claim 62, wherein the VL sequence comprises SEQ ID NO:93.

64. The method of any one of claims 59-63, wherein the agonist anti-TREM2 antibody comprises a VH sequence comprising SEQ ID NO:97 and a VL sequence comprising SEQ ID NO:93.

65. The method of claim of any one of claims 1-32, wherein the agonist anti-TREM2 antibody comprises: i. a CDR-H1 sequence comprising the sequence of SYWIA (SEQ ID NO: 106); ii. a CDR-H2 sequence comprising the sequence of IIYPGDSDTRYSPSFQG (SEQ ID NO: 99); iii. a CDR-H3 sequence comprising the sequence of QRTFYYDSSDYFDY (SEQ ID NO: 107); iv. a CDR-L1 sequence comprising the sequence of RASQGISSWLA (SEQ ID NO: 102); v. a CDR-L2 sequence comprising the sequence of AASSLQN (SEQ ID NO: 103); and vi. a CDR-L3 sequence comprising the sequence of QQADSFPRT (SEQ ID NO: 104).

66. The method of claim 65, wherein the agonist anti-TREM2 antibody comprises a VH sequence comprising a sequence that has at least 85%, 90%, or 95% sequence identity to SEQ ID NO: 105.

67. The method of claim 66, wherein the VH sequence comprises SEQ ID NO: 105.

68. The method of any one of claims 65-67, wherein the agonist anti-TREM2 antibody comprises a VL sequence comprising a sequence that has at least 85%, 90%, or 95% sequence identity to SEQ ID NO: 101.

69. The method of claim 68, wherein the VL sequence comprises SEQ ID NO: 101.

70. The method of any one of claims 65-69, wherein the agonist anti-TREM2 antibody comprises a VH sequence comprising SEQ ID NO: 105 and a VL sequence comprising SEQ ID NO: 101.

71. The method of any one of claims 1-32, wherein the agonist anti-TREM2 antibody comprises: i. a CDR-H1 sequence comprising the sequence of YAFSSQWMN (SEQ ID NO:113); ii. a CDR-H2 sequence comprising the sequence of RIYPGCKIDTNYAGKFQG (SEQ ID NO: 114); iii. a CDR-H3 sequence comprising the sequence of ARLL.RNQPGESYAMDY (SEQ ID NO: 115); iv. a CDR-L1 sequence comprising the sequence of RSSQSLVHSNRYTYLH (SEQ ID NO: 109); v. a CDR-L2 sequence comprising the sequence of KVSNRFS (SEQ ID NO: 110); and vi. a CDR-L3 sequence comprising the sequence of SQSTRVPYT (SEQ ID NO: 111).

72. The method of claim 71, wherein the agonist anti-TREM2 antibody comprises a VH sequence comprising a sequence that has at least 85%, 90%, or 95% sequence identity to SEQ ID NO: 112.

73. The method of claim 72, wherein the VH sequence comprises SEQ ID NO: 112.

74. The method of any one of claims 71-73, wherein the agonist anti-TREM2 antibody comprises a VL sequence comprising a sequence that has at least 85%, 90%, or 95% sequence identity to SEQ ID NO: 108.

75. The method of claim 74, wherein the VL sequence comprises SEQ ID NO: 108.

76. The method of any one of claims 71-75, wherein the agonist anti-TREM2 antibody comprises a VH sequence comprising SEQ ID NO: 112 and a VL sequence comprising SEQ ID NO: 108.

77. The method of any one of claims 33-76, wherein the agonist anti-TREM2 antibody further comprises a first Fc polypeptide.

78. The method of claim 77, wherein the agonist anti-TREM2 antibody further comprises a second Fc polypeptide, wherein the second Fc polypeptide forms an Fc dimer with the first Fc polypeptide.

79. The method of claim 78, wherein the first Fc polypeptide and the second Fc polypeptide each contain modifications that promote heterodimerization.

80. The method of claim 79, wherein the first Fc polypeptide has a T366W substitution and the second Fc polypeptide has T366S, L368A, and Y407V substitutions, according to EU numbering.

81. The method of claim 79, wherein the first Fc polypeptide has T366S, L368A, and Y407V substitutions and the second Fc polypeptide has a T366W substitution, according to EU numbering.

82. The method of any one of claims 78-81, wherein the first Fc polypeptide and/or the second Fc polypeptide further comprise one or more modifications that reduce effector function and/or extend serum half-life.

83. The method of any one of claims 78-82, wherein the first Fc polypeptide and/or the second Fc polypeptide comprise one or more substitutions independently selected from the group consisting of L234A, L235A, R292C, N297G, V302C, P329G, P331S, D356E, L358M, M428L, E430G, and N434S, according to EU numbering.

84. The method of claim 83, wherein the first Fc polypeptide and/or the second Fc polypeptide comprise L234A and L235A substitutions, according to EU numbering.

85. The method of claim 83 or 84, wherein the first Fc polypeptide and/or the second Fc polypeptide comprise M428L and N434S substitutions, according to EU numbering.

86. The method of any one of claims 78-85, wherein the first Fc polypeptide comprises a sequence that has at least 85%, 90%, or 95% sequence identity to SEQ ID NO:38 or 119, and the second Fc polypeptide comprises a sequence that has at least 85%, 90%, or 95% sequence identity to SEQ ID NO:38 or 119.

87. The method of claim 86, wherein the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising a sequence that has at least 85%, 90%, or 95% sequence identity SEQ ID NO:38;

(ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising a sequence that has at least 85%, 90%, or 95% sequence identity SEQ ID NO:38; and

88. The method of claim 86, wherein the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising a sequence that has at least 85%, 90%, or 95% sequence identity SEQ ID NO: 119;

(ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising a sequence that has at least 85%, 90%, or 95% sequence identity SEQ ID NO: 119; and

89. The method of any one of claims 87-88, wherein:

(a) each VH comprises SEQ ID NO:24 and each VL comprises SEQ ID NO:22;

(b) each VH comprises SEQ ID NO:89 and each VL comprises SEQ ID NO:85;

(c) each VH comprises SEQ ID NO:97 and each VL comprises SEQ ID NO:93;

(d) each VH comprises SEQ ID NO: 105 and each VL comprises SEQ ID NO: 101; or

(e) each VH comprises SEQ ID NO: 112 and each VL comprises SEQ ID NO: 108.

90. The method of any one of claims 78-89, wherein the first Fc polypeptide and/or the second Fc polypeptide is modified to specifically bind to a transferrin receptor (TfR).

91 , The method of claim 90, wherein the first Fc polypeptide is modified to specifically bind to a TfR.

92. The method of claim 90 or 91, wherein the first Fc polypeptide comprises: Trp, Leu, or Glu at position 380; Tyr or Phe at position 384; Thr at position 386; Glu at position 387; Trp at position 388; Ser, Ala, or Vai at position 389; Ser or Asn at position 390; Thr or Ser at position 413; Glu or Ser at position 415; Glu at position 416; and Phe at position 421, according to EU numbering.

93. The method of claim 92, wherein the first Fc polypeptide 1) comprises a sequence that has at least 80%, 85%, 90%, or 95% sequence identity to a sequence selected from the group consisting of SEQ ID NOS:47, 68, 38, 39, 46, 49, 50, 61, 63, 70, 84, and 116-124; and 2) comprises: Trp, Leu, or Glu at position 380; Tyr or Phe at position 384; Thr at position 386; Glu at position 387; Trp at position 388; Ser, Ala, or Vai at position 389; Ser or Asn at position 390; Thr or Ser at position 413; Glu or Ser at position 415; Glu at position 416; and Phe at position 421, according to EU numbering.

94. The method of claim 92, wherein the first Fc polypeptide 1) comprises a sequence that has at least 90% or 95% sequence identity to a sequence selected from the group consisting of SEQ ID NOS: 47, 68, 46, 49, 50, 70, 117, 118, and 121-124; and 2) comprises: Trp, Leu, or Glu at position 380; Tyr or Phe at position 384; Thr at position 386; Glu at position 387; Trp at position 388; Ser, Ala, or Vai at position 389; Ser or Asn at position 390; Thr or Ser at position 413; Glu or Ser at position 415; Glu at position 416; and Phe at position 421, according to EU numbering.

95. The method of claim 92, wherein the first Fc polypeptide 1) comprises a sequence that has at least 90% or 95% sequence identity to a sequence selected from the group consisting of SEQ ID NOS: 47, 68, 50, 70, 117, 118, 122, and 124; and 2) comprises: Trp, Leu, or Glu at position 380; Tyr or Phe at position 384; Thr at position 386; Glu at position 387; Trp at position 388; Ser, Ala, or Vai at position 389; Ser or Asn at position 390; Thr or Ser at position 413; Glu or Ser at position 415; Glu at position 416; and Phe at position 421, according to EU numbering.

96. The method of any one of claims 92-95, wherein the second Fc polypeptide comprises a sequence that has at least 90% or 95% sequence identity to a sequence selected from the group consisting of SEQ ID NOS: 39, 63, 38, 61, 84, 116, 119, and 120.

97. The method of any one of claims 92-95, wherein the second Fc polypeptide comprises a sequence that has at least 90% or 95% sequence identity to a sequence selected from the group consisting of SEQ ID NOS: 39, 63, 61, 84, 116 and 120.

98. The method of any one of claims 95-97, wherein the first Fc polypeptide comprises a sequence selected from the group consisting of SEQ ID NOS:47 and 68, and the second Fc polypeptide comprises a sequence selected from the group consisting of SEQ ID NOS:39, 63, 61 and 84.

99. The method of claim 98, wherein the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising SEQ ID NO: 47;

(ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising SEQ ID NO:39 or 61; and

100. The method of claim 98, wherein the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising SEQ ID NO:68;

(ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising SEQ ID NO: 63 or 84; and

101. The method of any one of claims 99-100, wherein: (a) each VH comprises SEQ ID NO:24 and each VL comprises SEQ ID NO:22;

(b) each VH comprises SEQ ID NO:89 and each VL comprises SEQ ID NO:85;

(c) each VH comprises SEQ ID NO:97 and each VL comprises SEQ ID NO:93;

(d) each VH comprises SEQ ID NO: 105 and each VL comprises SEQ ID NO: 101; or

(e) each VH comprises SEQ ID NO: 112 and each VL comprises SEQ ID NO: 108.

102. The method of claim 101, wherein the agonist anti-TREM2 antibody comprises:

(ii) a second HC that comprises or consists of the amino acid sequence set forth in SEQ ID NO:53 or 52; and

103. The method of claim 101, wherein the agonist anti-TREM2 antibody comprises:

(ii) a second HC that comprises or consists of the amino acid sequence set forth in SEQ ID NO: 73 or 72; and

104. The method of any one of claims 95-97, wherein the first Fc polypeptide comprises a sequence selected from the group consisting of SEQ ID NOS:50 and 70, and the second Fc polypeptide comprises a sequence selected from the group consisting of SEQ ID NO:39 and 63.

105. The method of claim 104, wherein the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising SEQ ID NO:50;

(ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising SEQ ID NO: 39; and (iii) two light chains each comprising a VL comprising a sequence selected from the group consisting of SEQ ID NOS: 22, 85, 93, 101, and 108.

106. The method of claim 104, wherein the agonist anti-TREM2 antibody comprises:

(i) a first heavy chain (HC) comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the first Fc polypeptide comprising SEQ ID NO:70;

(ii) a second HC comprising 1) a VH comprising a sequence selected from the group consisting of SEQ ID NOS: 24, 89, 97, 105, and 112; and 2) the second Fc polypeptide comprising SEQ ID NO: 63; and

107. The method of any one of claims 105-106, wherein:

(a) each VH comprises SEQ ID NO:24 and each VL comprises SEQ ID NO:22;

(b) each VH comprises SEQ ID NO:89 and each VL comprises SEQ ID NO:85;

(c) each VH comprises SEQ ID NO:97 and each VL comprises SEQ ID NO:93;

(d) each VH comprises SEQ ID NO: 105 and each VL comprises SEQ ID NO: 101; or

(e) each VH comprises SEQ ID NO: 112 and each VL comprises SEQ ID NO: 108.

108. The method of claim 107, wherein the agonist anti-TREM2 antibody comprises:

(ii) a second HC that comprises or consists of the amino acid sequence set forth in SEQ ID NO: 53; and

109. The method of claim 107, wherein the agonist anti-TREM2 antibody comprises:

(ii) a second HC that comprises or consists of the amino acid sequence set forth in SEQ ID NO: 73; and (iii) a first and a second light chain (LC) that each comprises or consists of the amino acid sequence set forth in SEQ ID NO:54.