NZ731196B2 - A novel purification process for isolation and commercial production of recombinant tnk-tpa (tenecteplase) - Google Patents

Abstract

The present invention relates to a process of isolating and purifying tissue plasminogen activator and its variants more specifically TNK-tPA from CHO cells, the process uses a series of affinity chromatography and filtration steps to overcome known difficulties in the industrial scale purification of TNK-tPA. of TNK-tPA.

Description

A NOVEL ERR}E‘iCA’i‘EON PROCESS FOR ESQLATEON AME) C(EMIWERCEAL PROBUCTEGN 0F RECQMBENANT TNKnT?A "TENECTEPLASE HELD 917 THE ENVENTEON Present invention is related to a novel process of isolation, purification and production of tissue plasminogen activator PA) from mammalian cells, more specifically from Chinese Hamster Ovary (CHO) cells.

BACKGROUND 0? TEE EN‘VENTION Tenecteplase (TNK—tPA) is a recombinant glycoprotein of serine protease family with six amino acids tution in the native human tissue nogen activator (t—PA) with 17 disulphide bridges and having molecular weight of . In the pment of TNK—tPA, the modifications made in native t—PA includes tution of threonine 103 with asparagine, tution of asparagine 117 with glutamine both within the kringle 1 domain, and the substitution of lysine, histidine and two arginine with tetra—alanine amino acids at 296—299 positions in the protease domain to make the resulting protein highly fibrin specific with longer plasma half life and 80% decreased susceptibility to degradation by nogen activator inhibitor—1 (PAI—l) compared to native t—PA.

The TNK in TNK—TPA refers to the sites of the t—PA molecule that have been modified i.e.TlO3; N1 17; and KHRR 296—299.The aforementioned modifications of TNK—tPA renders its use as an improved eutic agent for the treatment of acute myocardial infarction which has better therapeutic compliance because the greater fibrin specificity allows for faster and complete clot lysis with decreased ng complications and the long pan permits a single bolus dose with less systemic fibrinolysis and lesser bleeding complications from the previous clot buster drugs.

The mechanism of TNK—tPA is initiated on binding of TNK—tPA to the fibrin component of the thrombus (blood clot) which selectively converts inalctive plasminogen into plasmin and consequently the resultant plasmin degrades the matrix of thrombus in occluded artery while conserving fibrinogen and zing systemic plasminogen activation due to its highly specific nature.

The benefits of TNK—tPA seen in myocardial infarction patients and the encouraging results from animal studies in the context of Acute Ischemic Stroke (AIS), suggested that TNK—tPA might prove to be a safer and more effective y than ase, the only drug ed by USFDA for AIS. Over the past few years, several clinical trials evaluated the use of TNK— tPA in AIS and proved that TNK—tPA has a better pharmacological profile than alteplase and also suggested that it could be an effective and safe therapeutic option in treating AIS in patients reporting within 4.5 h after symptom onset. ly, TNK—tPA has been considered for the treatment of patients with pulmonary embolism and several clinical trials showed promising outcomes. A large number of clinical trials are still being conducted to assess the complete conclusive picture of TNK—tPA in l indications.

In the last few years, development and manufacturing of recombinant giycoproteins was carried out by batch, fed hatch, semi~fed batch and perfusion bioreactors processes and for purification of these proteins adsorption and ion exchange chromatography were majorly employed.

For t~PA and its variants certain purification ois are known in prior art cg. purification by immuno affinity (anti—tPA goat polyclonal antibody), ion exchange, ethanol precipitation, reverse phase chromatography, chromatography on silica or anion exchange, such as diethylamino ethyl, ammonium sulphate precipitation, sephadex— G—75 etc.

Some of the approaches for the purification of TNK t—PA is listed in prior art includes W0 til5922, sets out a purification process where series of ion ge chrornatt‘rgraphy steps, immunoaffinity chromatography and ultrafil'tration/diafiitration steps are used for purification of 'E‘NK—tPA. Wt} zeta/usessa A, sets out a purification process prirnatiiy drawn to the use of hydrophobic interaction chromatography.

The immune affinity tography used in the prior art is not suitable technique for commercial cturing of TNK—tPA. Not only it could raise lot of tory coneems but the cost of immune affinity chromatography media is also very high compared to com'entional chn'irnatography matrices owing to their use of rnonocioual antibodies for preparation. Hydrophobic interaction chromatography described in certain prior art for IN Kr- tPA cation uses isopropyl alcohoi (IPA) in the process which is an organic solvent and known for ng aggregation and denaturation of proteins and may he considered as one of the disadvantages of the prier art. "l‘NK-tl’A is a highly unstable molecule and hence use of {PA in the purificatitm prneess sheuld be avoided as it may lead to the denaturatien of the protein. ln additinn, the large volume usage of EPA at commercial scale tvnuld require recycling of lPA whieh again demands additienal energy consumption and extra investment such as snlvent recovery unit. 'l‘herel’ore, none (if the aforementioned processes are capable 0f prnviding an efficient, scalable and robust pnrifieatinn solution, which could consistently produce TNK—tPA drug substance at emnrnereial seale, meeting all the required Sp ations Renee, there is a need fer an effective and cmnrnercially viable prneess fer cation of ’l‘NKutl’A.

GREECE {39F THE lNVlEN’E‘EON The object of the present invention is to develop an efficient, robust, scalable, and commercially viable purification process for the production of TNK—tPA resulting yield not less than 60% and purity more than 95% as measured by Size exclusion chromatography.

SUMMARY 0F ’l‘HlEl ENVEN’E‘EQN The present invention relates to a novel process of isolating and purifying tissue plasminogen tor and its ts more specifically TNK—tPA from CHO cells and bes an industrially applicable, simple, cost effective, robust and highly efficient process of A purification.

A s for isolation and purification of TNK—tPA of the present invention comprising steps of: i) subjecting cell free harvest obtained from CHO cell culture to affinity chromatography to capture TNK—tPA and obtaining an eluate containing partially purified TNK—tPA. (ii) subjecting the eluate of step (i) to ty chromatography for additional purification of TNK—tPA and obtain an eluate containing ily A. (iii) viral inactivation of eluate of step (ii) to obtain the viral vated sample; 4 [followed by page 4A] (iv) subjecting the viral inactivated sample of step (iii) to a further affinity chromatography for additional purification to obtain an eluate containing primarily highly purified TNK-tPA; (v) subjecting the eluate of step (iv) to cation exchange chromatography to obtain an eluate containing highly purified preparation of TNK-tPA; (vi) subjecting the eluate of step (v) to virus reduction filtration for removal of virus present; (vii) concentrating the sample of step (vi) to obtain TNK- tPA; wherein the yield of the process is more than 60 % and purity of TNK-tPA obtained is more than 95% as measured by Size exclusion chromatography.

In one particular aspect the invention provides a process for ion and purification of TNK-tPA comprising steps of: (i) subjecting cell free harvest obtained from CHO cell culture to affinity chromatography-I to capture A and obtaining an eluate containing partially purified TNK-tPA; wherein the affinity tography-I comprises Blue ose 6 FF as a stationary phase and a mobile phase, n the mobile phase is a mixture of sodium ate buffer, sodium chloride and urea; (ii) subjecting the eluate of step (i) to ty chromatography-II for additional purification of TNK-tPA and obtain an eluate containing primarily TNK-tPA; wherein the affinity chromatography-II comprises Lysine Hyper D as a stationary phase and a mobile phase, wherein the mobile phase is a mixture of sodium acetate buffer, urea and epsilon aminocarproic acid (EACA); (iii) viral inactivation of eluate of step (ii) to obtain the viral inactivated sample; wherein viral inactivation is conducted by low pH and chemical inactivation, wherein chemical inactivation is done by ng the sample with sodium caprylate in the presence of urea; 4A [followed by page 4B] (iv) subjecting the viral inactivated sample of step (iii) to a further affinity chromatography-III for additional cation to obtain an eluate containing primarily highly purified TNK-tPA; wherein the affinity chromatography-III comprises Ceramic Hydroxy Apatite (CHT) as a stationary phase and a mobile phase, wherein the mobile phase is a mixture of phosphate buffer, 2-(N-Morpholino) ethanesulfonic acid hydrate (MESHydrate ), sodium chloride and urea; (v) subjecting the eluate of step (iv) to cation exchange chromatography to obtain an eluate containing highly purified preparation of TNK-tPA; wherein the cation exchange chromatography comprises Fractogel SO3 as a stationary phase and a mobile phase, wherein the mobile phase is a mixture of L-Arginine, phoric acid and polysorbate-20; (vi) subjecting the eluate of step (v) to virus reduction filtration for removal of virus t; wherein virus filtration is d out by polyethersulphone (PES) nanofilter having a size in the range from 15-20 nm; and (vii) concentrating the sample of step (vi) to obtain TNK- tPA; wherein the yield of the s is more than 60% and purity of TNK-tPA obtained is more than 95% as measured by Size exclusion chromatography.

BRIEF DESCRIPTION OF DRAWINGS Figure 1: Depicts a chromatogram of affinity-I cation where first peak represents ties and second peak corresponds to eluate ning TNK-tPA.

Figure 2: Depicts a SDS PAGE r stained) profile of affinity-I purification where lane no 5, 6 and 7 showing wash fractions (1, 2 and 3 tively) and Lane No. 9 corresponds to eluate containing TNK-tPA.

Figure 3: Depicts a chromatogram of affinity- II purification, UV 280 peak corresponding to eluate containing TNK-tPA.

Figure 4: Depicts a SDS PAGE (silver stained) profile of affinity-II purification where lane No. 9 corresponds to eluate containing TNK-tPA Figure 5: Depicts a chromatogram of affinity- III purification, UV 280 peak (first) corresponds to eluate containing TNK-tPA Figure 6: Depicts a SDS PAGE (silver d) profile of affinity-III purification where lane No. 9 corresponds to eluate containing TNK-tPA Figure 7: Depicts a togram of cation exchange purification, UV 280 peak corresponds to eluate containing TNK-tPA.

Figure 8: Depicts a SDS PAGE (silver stained) profile of cation exchange purification where lane No. 5 corresponds to eluate containing TNK-tPA.

Figure 9: Depicts a ison of ng SDS-PAGE (silver stained) profile of drug nce obtained after purification using steps described in present invention and innovator product (Metalyse).

[FOLLOWED BY PAGE 5] Figure it}: Depicts a comparison of non reducing SDS RAGE (silver stained) profile of drug substance obtained after purification using steps described in present invention and innovator product (Metalyse).

Figure ii: Depicts a peptide inap cin‘oniatogram of drug substance obtained after purification using step described in present invention resembles with tor product (Metaiyse) Figure 12: Depicts a immune blotting of drug substance obtained after purification using steps described in present invention resembles with innovator product {Metaiyse} Figure 13: Depicts the breakthrough curve of Affinity-l (Blue Sepahrose FF) in batci'i mode.

Figure 14: Depicts Chromatograms for the PCC run over two cycles for (a) Column A —first column in the loading zone ; (b) Column B — the second column in the loading zone ; (0) Column C — the third column in the loading zone. ; (d) Column chromatograms mposed on each other showing full PCC run. UV is measured at 280 nm. Run performed on an XKl6—5ml Blue Sepharose Fast Flow.

Figure 15: Depicts Chromatogram from the first coiumn (Column A) overioading and capture in Column 8, UV measured at 280 um. Run performed on an Xtil i Blue Sepharose Fast Flow.

Figure 16: Depicts Chromatogram from the third column (Column C) g all post load washing. Impact of wash steps are denoted by A — Wash 1, B— Wash 2, C— wash 3, D — n, E— Regeneration 1, F— Regeneration 2, G—Regeneration 3, H—Regeneration 4. UV measured at 280 nm. Run performed on an XKl6—5ml Blue Sepharose Fast Flow.

DETAILED DESCRIPTION OF INVENTION The present ion s to a novel process of isolating and purifying tissue nogen activator and its variants more ically TNK—tPA. The cell free t is obtained from the cells cultured in bioreactors. The list of symbols and abbreviations used in specification of the present invention are listed at Table A below: Table A: List of symbols and iations tPA Tissue Plasminogen Activator CHO Chinese Hamster Ovary kDa Kilo—Dalton PAI Plasminogen Activator Inhibitor WO 63299 AIS Acute Ischemic Stroke SDS PAGE Sodium l Sulfate Polyacrylamide Gel Electrophoresis IPA Isopropyl Alcohol CHT Ceramic y Apatite FF Fast Flow mM Milli Molar MTX Methotrexate EACA Epsilon—aminocaproic acid MES— Hydrate 2—(N—Morpholino) ethanesulfonic acid hydrate TFF Tangential Flow Filtration UF Ultrafiltration DF Diafiltration PES Polyethersulphone PVDF Polyvinylidene Fluoride u Micron or Micrometer XMuLV Xenotropic Murine Leukemia Virus PRV Pseudorabies Virus Reo—3 Reovirus Type 3 MMV Murine Minute Virus CV Column Volume DBC Dynamic Binding ty HCP Host Cell n DNA De—oxyribo Nucleic Acid HCD Host Cell DNA SEC— HPLC Size Exclusion Chromatography HPLC High Performance Liquid Chromatography LAL Limulous Amoebocyte Lysate UV Ultraviolet MMC Mixed Mode Chrmnatography The present invention relates to a novel process of isolating and purifying tissue plasminogen activator and its variants more specifically TNK—tPA from CHO cells and describes an industrially applicable, , cost effective, robust and highly efficient process of TNK—tPA purification A process for isolation and cation of TNK—tPA of the present invention comprising steps of: i) subjecting cell free harvest obtained from CHO cell culture to ty chromatography to e TNK—tPA and obtaining an eluate containing partially purified TNK—tPA. (ii) subjecting the eluate of step (i) to affinity chromatography for additional purification of A and obtain an eluate containing primarily TNK—tPA. (iii) viral inactivation of eluate of step (ii) to obtain the viral inactivated sample; (iv) subjecting the viral inactivated sample of step (iii) to a further affinity chromatography for additional purification to obtain an eluate containing ily highly purified TNK—tPA; (v) subjecting the eluate of step (iv) to cation exchange chromatography to obtain an eluate containing highly purified preparation of A; (vi) subjecting the eluate of step (v) to virus reduction filtration for removal of virus present; (vii) concentrating the sample of step (vi) to obtain TNK— tPA; wherein the yield of the process is more than 60 % and purity of TNK—tPA obtained is more than 95% as measured by Size exclusion chromatography.

The process of the present invention may be explained by rating the steps as below: (i) Subjecting cell free harvest obtained from CHO cell culture to affinity chromatography to e TNK-tPA and obtaining an eluate containing partially purified TNK-tPA.

The cell free harvest containing TNK—tPA may be obtained from perfusion technology based fermentation system by CHO cells. The harvest ning TNK—tPA may be filtered with 0.2 u and collected in sterile ners and stored at 2—8°C till further use. The cell free harvest containing TNK—tPA is subjected to affinity chromatography. The stationary phase of affinity chromatography may be selected from the group comprising Blue Sepharose 6 fast flow, Lysine Hyper D, Ceramic Hydroxy Apatite (CHT), preferably the stationary phase is Blue Sepharose 6 FF. The column may be equilibrated by using a buffer comprising Phosphate buffer, sodium chloride and polysorbate 20 or their mixtures. The elution buffer or mobile phase employed for capture step ity Chromatography) may be individually or in ation selected from phosphate buffer, urea, and sodium chloride. More ably, the elution buffer or mobile phase is used in combination. The concentration of sodium phosphate in buffer used is preferably 20—50 mM sodium phosphate, more preferably 20—40mM. The concentration of sodium chloride used in the buffer is 1—2.5 M NaCl, more preferably l.5—2M.The tration of urea in the buffer may be in the range of 1—4 molar, preferably in the range of 2—3 molar. The pH of the elution buffer or mobile phase may be maintained in the range of 7—8, preferably in the range of 7—7.6, more preferably in the range of 4.

The removal of host cell proteins from products produced in mammalian cells is always a difficult task. In the present invention the step optimized as capture chromatography in current invention selectively removes host cell proteins to an extent of 0.8 to 1.5 log, more specifically 1.0 log which helps in achieving final concentration of HCP in purified TNK—tPA preparation, below 100 ppm.

Not only the host cell proteins (HCP) are reduced but process related impurities such as albumin, gentamycin, Methotrexate (MTX) etc. are also removed ively by the capture chromatography described in present invention. (ii) ting the eluate of step (i) to affinity chromatography for additional ation of TNK-tPA to obtain an eluate containing primarily TNK-tPA.

The eluate of step (i) may be subjected to affinity chromatography. The stationary phase or column material may be selected from the group comprising of Blue Sepharose 6 fast flow, Lysine Hyper D, Ceramic Hydroxy Apatite (CHT), etc., preferably the stationary phase is Lysine Hyper D. The equilibration buffer ed in ty chromatography step may be individually or in combination selected from Phosphate buffer, sodium chloride and polysorbate. More preferably the equilibration buffer is used in ation.

The column may be eluted by a elution buffer or mobile phase selected from the group comprising individually or in combination selected from sodium acetate, urea and Epsilon—aminocaproic acid (EACA). The pH of the affinity chromatography WO 63299 elution buffer may be done in the range of pH 3.5—6, preferably 4—5, more preferably 4.5-5.

The chromatography matrix ed for intermediate cation e.g. Affinity—II chromatography step may be selected from the group comprising of Blue Sepharose 6 fast flow, Lysine Hyper D and Ceramic Hydroxy Apatite (CHT), preferably the chromatography matrix used is Lysine Hyper D.

The n buffer ed in Affinity chromatography step may be 5—25 mM sodium acetate, 1—4 M urea, 01—04 M EACA having pH 4.0—5 .0. The concentration of sodium acetate in elution buffer is 5—25 mM, preferably in the range of 5—15 mM.

The concentration of EACA in the buffer is 01—04 mM, preferably in the range of 0.1—0.2 M. The concentration of urea is 1—4 M in the buffer, preferably in the range of 2—3 M.

The inventive merit of elution buffer by using EACA at acidic pH in this step is to e the most suitable condition. The process of the present invention as set out herein is most suitable for viral inactivation and reduces the handling and material consumption by several folds. Approximately 2—4 log reduction of viral clearance and 1—1.5 log reduction of host cell ns (HCP) are achieved by Affinity chromatography used in present invention. On an average the 1.69 log reduction with XMuLV and 4.30 log reduction with PRV are achieved by Affinity chromatography used in present ion. (iii) Viral inactivation of eluate of step (ii) to obtain the viral inactivated sample; The viral inactivation of the eluate obtain from step (ii) may be conducted by any method such as heat treatment (Pasteurization, Lyophilisation/dry heat), irradiation, ultraviolet (UV), high tatic pressure, low pH incubation, chemical and solvent/detergent treatments. Chemical inactivation or viral inactivation is done by treating the sample with chemical selected from the group comprising sodium cholate, triton, Beta—propiolactone, tri(n—butyl)phosphate (TNBP), and sodium caprylate, preferably treating the sample with sodium caprylate at low pH in the presence of Urea. The tration of chemical/detergent is in the range of 0.001% to 0.10% W/v, preferably 0.01% — 0.07% (W/v), more preferably 0.05%.The concentration of urea is used in the range of 1—4 M, ably 2—3 M. The viral activation may also be carried out by incubating the sample for a period of 40—180 minutes, more preferably for a period of 40—80 minutes, in the temperature range of l5—45°C, more preferably in the range of 20—300C.

Generally low pH is the choice and most Widely used method of viral inactivation in purification processes. Low pH is known to vate enveloped viruses but it cannot inactivate highly resistant non enveloped viruses. The pH is in range from 4.0 to 4.7, more preferably in range from 4.3 to 4.7.

The composition of viral vation buffer described in present invention is optimized in such a manner that it could inactivate both ped and non enveloped viruses efficiently. Use of the als/detergents, urea, EACA and low pH of the t invention makes the conditions lethal for enveloped and non enveloped viruses and makes the combination an optimum choice for inactivating highly resistant viruses. On an average 5.65 log reduction With XMuLV and 5.38 log reduction with PRV are achieved by low pH and chemical inactivation of the present invention.

(M Subjecting the viral inactivated sample of step (iii) to a further affinity chromatography to obtain an eluate containing TNK-tPA; The viral inactivated sample of step (iii) may be subjected to a further affinity chromatography. The stationary phase or column material of affinity tography may be selected from the group of Blue Sepharose 6 fast flow, Lysine Hyper D, Ceramic Hydroxy Apatite (CHT), etc., preferably the nary phase or chromatography matrix used is Ceramic Hydroxy Apatite (CHT). The stationary phase or column may be eluted by a mobile phase or buffer selected from the group comprising individually or in combination selected from Phosphate buffer, 2—(N— Morpholino) ethanesulfonic acid e (MES— Hydrate), sodium chloride and urea.

The pH of the affinity chromatography elution buffer may be done at pH g from 6—9, preferably 6—8, more preferably 6—7.

The mobile phase or elution buffer employed in Affinity chromatography step may be —50 mM phospahte buffer, preferably in the range of 5—15 mM. The concentration of urea is used in the range of 1—4 M in buffer, ably in the range of 1—3 M. The concentration of MES— e used may be 2—20 mM in the buffer. Elution may be d by increasing concentration of salt. The salt of this n may be selected from group of potassium chloride, sodium chloride, sodium phosphate and ammonium sulphate, preferably the salt is sodium chloride and concentration of sodium chloride is in range of 0.1—1.0 M sodium chloride. The elution type may be linear, step or in combination of both, preferably the elution used is linear salt gradient.

Affinity chromatography (multimode chromatography) used in present invention is to remove traces of impurities, specifically host cell DNA (HCD), host cell proteins(HCP) and viral impurities if any. Approximately 2—4 log reduction of viral clearance and 0.5 —l log reduction of HCP is achieved using affinity—III chromatography mentioned in t invention. On an average 4.23 log reduction with XMuLV, 4.06 log reduction with PRV, 3.73 log reduction With Reo—3 and 2.97 log reduction with MMV are achieved by Affinity tography used in present invention.

Subjecting the eluate of step (iv) to cation exchange chromatography to obtain an eluate containing highly purified ation of A in formulation buffer; The cation exchange chromatography of the eluate of step (iv) may be conducted by using a matrix or stationary phase selected from the group comprising Fractogel S03, Fratogel SE Hicap, SP Sepharose FF, CM Sepharose FF etc., preferably the chromatography matrix or stationary phase used is Fractogel S03. The equilibration buffer employed in cation exchange tography may be individually or in combination selected from group comprising phosphate buffer, urea, MES and sodium chloride, preferably the equilibration buffer is used in combination.

The elution buffer or mobile phase employed in cation exchange chromatography may be individually or in combination selected from nine, O—phosphoric acid and rbate—20, ably, the elution buffer is used in combination or mixture.

The mobile phase or elution buffer employed in cation exchange chromatography comprising L—Arginine present in range from 10—350 mM, preferably in range from 250—350 mM, O—phosphoric acid present in range from 0.5—1%, preferably in range from 0.6%—0.8% and polysorbate—20 present in range from 0.01—0.05%, preferably in range from 0.04 to 0.05 % . The pH of the cation exchange chromatography elution buffer or mobile phase may be done in the range of 7.0 to 7.5, preferably in the range 7.3— 7.5.

Generally the ion exchange chromatography is used as e, intermediate and polishing chromatography to either remove bulk or traces of impurities. In present invention the cation exchange chromatography is somewhat used differently than it is conventionally used. Herein, the eluate of us chromatography is directly loaded on to cation exchange chromatography to obtain the highly purified ation of TNK—tPA in final formulation buffer containing arginine, hosphoric acid and polysorbate 20. The advantage of using cation exchange chromatography differently is that buffer exchange and simultaneous concentration and purification are achieved in a single step. In prior art techniques like gel filtration tography and diafiltration using Tangential Flow Filtration (TFF) are employed for buffer exchange. These techniques are efficient and most commonly used for buffer exchange but cannot further purify target protein. Due to the fact that one can only load m 30% of sample to column volume in gel filtration chromatography, bigger size of columns are required compared to ion exchange tography. Gel filtration chromatography also causes the dilution of target protein during buffer exchange which further requires some additional concentration step like TFF. Buffer exchange using diafiltration is also not feasible When volumes to be buffer exchanged are higher since it es very high amount of buffer and demands large size of UF/DF unit. Considering entioned limitations of conventional buffer exchange techniques the cation ge chromatography described in present invention is capable to provides a buffer exchange step and assists in further cation also. It is possible to achieve a viral reduction factor of 1.21 log with non enveloped virus e.g.

MMV using ion exchange chromatography of the present invention. (vi) subjecting the eluate of step (v) to virus reduction tion for removal of virus present; The virus filtration may be performed after affinity chromatography, cation exchange chromatography, and tangential flow filtration step, more preferably the virus tion step is performed after cation exchange chromatography. Nanofilter ed for this step may be of 15 nm, 20 nm, and higher. Preferably the nanofilter size is between 15— 20 nm. The nanofilter used may be made up of cellulose, PES, PVDF etc. More preferably the filter used is PBS.

The filtration performed after virus filtration may be ed from microfiltration, ultra filtration, nano filtration, macro filtration, tial flow filtration, etc. More preferably the filtration is tangential flow filtration. On an average 4.15 log reduction with XMuLV, 3.40 log reduction with PRV, 4.41 log reduction with Reo—3, 4.76 log reduction with MMV are achieved by virus reduction filtration used in present invention.

The Overall downstream process provides more than 15 log reduction with XMuLV, more than 17 log reduction with PRV, more than 8 log reduction with Reo—3, and more than 8 log reduction with MMV.

The most probable contaminant in the process of TNK t—PA would be CHO cell derived retrovirus and XMuLV represents a non—defective C type irus for CHO cells, a more than 15 log reduction obtained for XMuLV is considered most nt and gives a high assurance in terms of viral safety. (vii) Concentrating the sample of step (vi) to obtain TNK-tPA.

The filtrate obtained in step (vii) is subjected to filtration method selected from the group comprising iltration, ultrafiltration, nanofiltration, microfiltration and tangential flow filtration, preferably the filtration method is tangential flow filtration.

Ultra filtration membrane selected for this step may be of 5, 10, 30 or 50kDa.

Preferably the ultra filtration membrane used is in the range of 5—30 kDa, more preferably the size of ultra filtration membrane used is 10 kDa. The Ultra tion membrane used may be made up of cellulose, PES, PVDF etc. More preferably the filter used is PBS. The concentration of TNK—tPA retentate may be in the range of 1.0i0.4mg/ml to 4mg/ml. More preferably, the concentration of TNK—tPA may be in the range of l.0i0.4mg/ml to 6.0i0.4mg/ml. Most preferably, the concentration of TNK—tPA is 5.5i0.4mg/ml.

The TNK—tPA drug substance (Tenecteplase) may ably be obtained by sterile filtration of TFF Retentate using 0.2 u sterilizing grade filters made up of PBS, PVDF, and Cellulose. More preferably sterile filter is made up of PBS.

The present ion also ses a process, wherein the batch Affinity—I chromatography may also be operated in continuous mode using periodic counter current chromatography (PCC). The use of FCC, provides additional advantage e.g. reduced buffer ption, increased productivity, steady state operation and better process controls. .

The present invention, includes Within its scope, the use of inline buffer and chromatography load conditioning cum preparation by five pump based customized AKTA process system With a maximum flow rate of 600 L/h. The said activity can be performed by Flow feedback or pH—Flow feedback mode of control for buffer and chromatography load preparation of Affinity—I, II, III and IEC tography steps as mentioned in Example 1 to 4.

The process of the present invention results in a purified product of TNK—tPA with increased yield and purity. The attributes of TNK—tPA obtained by the process of the present invention is set out in detail at Table B.

Table B: s pertaining to Quality of TNK-tPA S.No. Critical Quality Attribute Quality of Purified A BULK 1 Appearance Clear colorless to ly ish liquid 2 pH 7.0 -7.6 3 Protein (mg/ml) Not less than 5.0 mg/ml 4 No additional band other than principal band SDS PAGE Identified with specific antibody and resembles Immunoblotting with qualified standard 6 Bioactivity (U/mg) l60 U/mg to 240 U/mg 7 Monomer (%) More than 95% 8 Single Chain t (%) More than 60 % 9 HCP (ppm) Less than 100 ppm Sialic Acid (mol/mol of 2.9 to 5.7 moles/mol of TNK—tPA TPA) 11 l Sugar ol of .5 to 13.5 moles/mol of TNK—tPA TPA) 12 Type40 %, Type I 11 content , Type Type—II 60—72% 13 HCD Less than 10ng/dose 14 BET < 1EU/mg Serine(S)—Tyrosine(Y)—Glutamine(Q)— Valine(V)—Isoleucine(I)—Cysteine(C)—Arginine( N—Terminal Sequence (First R)—Aspartic acid(D)—Glutamic acid(E)— amino acid ) Lysine(K)_Threonine(T)—Glutamine(Q)— Methionine(M)—Isoleucine(I)—Tyrosine(Y) 16 Osmolality 260-320 mOsm/Kg 17 Arginine Content 50—60 mg/ml 18 Chromatogram n resembles with qualified Peptide mapping standard 19 UV Spectrum (Amax) 280i2nm In an embodiment the process of the present invention is e to remove or inactivate viruses as potential itious agents as assessed using a scaled down purification process.

The high log clearance values obtained for XMuLV, PRV, Reo—3 and MMV provides a very good assurance that any adventitious viruses which could not be detected, or might gain access to the production process, would be cleared/or inactivated, during highly capable purification process, mentioned in the current invention and thus reducing the l risk to patient safety.

In addition to higher assurance of viral safety, the aforementioned improvements in the cation process of TNK—tPA are also beneficial in terms of decreased human intervention, lower capital and operational expenditures for higher yield TNK—tPA preparation.

In an embodiment the t invention provides a pharmaceutical composition comprising the TNK—tPA retentate obtained from the process of present invention in liquid parenteral I.V formulation with pharmaceutically acceptable excipients for acute myocardial infarction and acute ischemic stroke.

In an embodiment the ceutical ition of present invention comprises: Ingredient Concentration eplase 5 mg Arginine 55 mg Polysorbate — 20 0.43 mg Phosphoric Acid 17 mg Water for injection q.s to 1.0 ml In r ment the present invention provides the use of the isolated and prepared TNK—tPA in liquid eral I.V formulation for acute myocardial infarction and acute ischemic stroke.

The invention is described in detail herein below with respect to the following examples which are provided merely for ration and are not intended to restrict scope of invention in any manner. Any embodiments that may be apparent to a person skilled in the art are deemed to fall within the scope of present invention.

Example- 1 The cell free harvest containing TNK—tPA is subjected to Affinity chromatography column packed with Blue Sepharose FF. before loading, the Column is equilibrated with 5 Column Volume (CV) of equilibration buffer. The loading is stopped till column achieve saturation.

The loading capacity of column is decided based on the Dynamic Binding Capacity (DBC) of column which is in range of l — 2 mg/ml. After loading, column is washed with equilibration buffer until loosely bound s and t related impurities were washed away in equilibration wash. For further removal of host cell proteins another wash buffer is used which is composed of urea, sodium chloride, sodium phosphate and polysorbate 20.

After column wash, TNK—tPA is eluted using elution buffer containing 20—50 mM Sodium Phosphate, 1—2 M NaCl, 2—3 M urea, and 0.04—0.l % polysorbate 20. Affinity—I eluate is filtered with 0.2um filter. Samples are awn and analysed by reduced and non reduced SDS PAGE to know the purity profile and single chain/double chain content. Those who skilled in art can understand the ality of single chain/double chain composition in final TNK—tPA drug nce.

The present invention is advantageous due to direct capture of clarified harvest without mixing in large mixing tanks.

Example- 2 Affinity—I Chromatography Eluate is diluted with affinity—II on or affinity chromatography equilibration buffer containing 20—50 mM Sodium Phosphate, 0.04—0.l % polysorbate20 at pH 7.2 to reduce the conductivity up to less than 15 ms/cm. Diluted sample is clarified using 0.2 u filter and loaded on to Affinity—II chromatography. Column is washed with bration buffer to bring the UV280 absorbance to baseline. Column is further washed to remove s and t related impurities with wash buffer containing 20—50 mM sodium ate, 1—3 M NaCl, 0.04—0.l% polysorbate 20 and pH 7.2.Purified TNK— tPA is recovered and eluted from the column by passing elution buffer consisting of 5—25 mM sodium acetate, 1—4 M urea, 0.1—0.4 M EACA and pH 4.0—5.0. All the chromatography samples including load, flow through, washes, and elution were analyzed using following analytical methods: SDS PAGE (reduced/non reduced) for purity and single chain/double chain content.

Size Exclusion High Performance Chromatography (SEC—HPLC) For Aggregate Content TNK —tPA content measured by Clot Lysis assay.

Total Protein by rd and UV280 nm.

HCP content using ELISA (Cygnus third generation kit) Affinity chromatography is optimized for removing process & product related impurities. The method of elution in this step is optimized in such a way that it complements to viral inactivation step and the composition with condition of elution buffer e.g. urea, EACA, and low pH are optimized to inline with viral inactivation. Approximately 2 to4 log reduction of viral clearance and 1.0 to 1.5 log reduction of host cell proteins (HCP) are achieved after Affinity—II chromatography step.

The other advantage is using EACA at acidic pH in ty tography—II in elution buffer inspite of L—Arginine and EACA at neutral pH. This particular change in purification step is valuable in reducing the cost of L—Arginine and also provides an optimum condition for viral inactivation. Hence, it can be stated that the same step is not only favorable for TNK—tPA n but also optimum for viral inactivation that in turn reduces the work load and material consumption with time.

Example- 3 The Elution of Affinity Chromatography is subjected to low pH and chemical inactivation using sodium caprylate. Mixture is incubated at 20 to 25°C for 60 min. In viral inactivation step, sodium ate used is in very low amount that eliminates the need of large mixing vessels. In prior art sodium caprylate was used to inactivate viruses present in before capture chromatography where s are comparatively higher hence quantity of sodium caprylate required was also high. In present invention, sodium Caprylate is added after second chromatography steps where volume to be handled is low and therefore es less amount of sodium ate and much smaller vessel for handling. Apart from that, the use of sodium caprylate at pH 4.5 as compared to neutral or alkaline pH, provides a more effective and robust viral inactivation in the process.

After viral inactivation the solution is diluted using ate buffer for loading on to Affinity chromatography (mixed mode tography) to remove traces of impurities, specifically HCD, HCP and viral impurities if any. Approximately 2—4 log reduction of viral clearance and 0.5 —l log reduction of HCP clearance are achieved by affinity chromatography. In prior art same c hydroxyl apatite is described for tissue plasminogen activator purification, but none of the s have described the capability to remove impurities e.g. HCP, DNA and viruses. Criticality of removing such ties is evident by the fact that the amount of these impurities is tested in final product (except viral load) and is part of final drug substance e specifications. All the chromatography samples including load, flow through, washes, and elution are analyzed using following analytical methods: SDS PAGE (reduced/non reduced) for purity and single chain/double chain content.

Size Exclusion High performance Chromatography (SEC—HPLC) for ate t TNK —tPA content measured by Clot Lysis assay.

Total Protein by Bradford and UV280 nm.

HCP content using ELISA (Cygnus third generation kit) Example- 4 The Affinity chromatography eluate without any conditioning is directly loaded on to cation exchange chromatography for concentration and buffer exchange of target protein. Cation ge chromatography is optimized in such a way that it avoids cumbersome dilution steps for feed conditioning and therefore the ty—III eluate can be directly loaded on to the cation exchange chromatography. TNK—tPA is red from the column by passing elution buffer containing 55 mg/ml L—Arginine, 17 mg/ml of orthophosphoric acid, 0.43 mg/ml Polysorbate 20 and pH 7.4.Cation exchange chromatography eluate is ted to filtration for viral reduction and the resultant filtrate is further concentrated using Tangential Flow Filtration (TFF) system to achieve the final drug substance concentration. After concentration the TFF Retentate is sterile filtered and kept at —20°C for further use. Drug nce produced by the purification process of present ion is thoroughly analyzed by the state of art and validated analytical procedures which includes but not limited to; Identity and purity check by SDS PAGE, Western Blot, N—terminal sequence analysis and peptide map, HCP determination using ELISA, ivity and TNK—tPA quantification using clot lysis assay, Host cell DNA quantification using qPCR, Endotoxin fication using LAL test, ate and single chain/double chain content using size ion HPLC, Arginine content & Osmolality, Sialic acid, neutral sugars, type—I and type—II glycoforms analysis, Analysis of process related impurities e.g. Gentamycin, MTX, Urea, Sodium Caprylate, and EACA using in—house developed methods.

After extensive analysis and biophysical comparison with innovator product it can be concluded that the product purified by the process described in current invention is yielding TNK—tPA product which is highly similar to innovator product with l process yield of more than 60%.

Example 5: A Periodic counter current tography (PCC) for affinity—I step has been med with cell culture supernatant containing TNK—tPA from perfusion based bioreactor. In batch mode dynamic binding capacity for affinity—I chromatography media were evaluated and based on the information obtained from break through analysis a three column FCC has been experimented on XKl6— 5 ml BLUE SEPAHROSE FF. The chromatographic buffer compositions were kept same as mentioned in Example—l.

Example 6: The method for ation of a liquid mixture of controlled pH & ionic strength for required buffers, dilution and/or conditioning of chromatography load by five pump based customized AKTA process system with a maximum flow rate of 600 L/h for TNK—tPA downstream processing. The liquid mixtures prepared with the above system With d recipes are suitable for purification of TNK—tPA at different chromatography stages as mentioned in Example—1 to 4.

WE

Claims (19)

CLAIM 1.:

1. A process for ion and cation of TNK-tPA si ng steps of: (i) subjecting cell free harvest ed from CHO cell culture to affinity chromatography-I to capture TNK-tPA and ing an eluate containing partially purified TNK-tPA; wherein the affinity chromatography-I comprises Blue Sepharose 6 FF as a stationary phase and a mobile phase, wherein the mobile phase is a mixture of sodium phosphate buffer, sodium chloride and urea; (ii) subjecting the eluate of step (i) to affinity chromatography-II for additional purification of TNK-tPA and obtain an eluate containing primarily TNK-tPA; wherein the affinity chromatography-II comprises Lysine Hyper D as a stationary phase and a mobile phase, wherein the mobile phase is a mixture of sodium acetate buffer, urea and epsilon aminocarproic acid ; (iii) viral inactivation of eluate of step (ii) to obtain the viral inactivated sample; n viral inactivation is conducted by low pH and chemical inactivation, wherein chemical inactivation is done by treating the sample with sodium caprylate in the presence of urea; (iv) subjecting the viral inactivated sample of step (iii) to a further affinity chromatography-III for additional purification to obtain an eluate containing primarily highly purified TNK-tPA; wherein the affinity chromatography-III comprises Ceramic Hydroxy Apatite (CHT) as a stationary phase and a mobile phase, n the mobile phase is a e of phosphate buffer, 2-(N-Morpholino) sulfonic acid hydrate (MESHydrate ), sodium chloride and urea; (v) subjecting the eluate of step (iv) to cation exchange chromatography to obtain an eluate containing highly purified preparation of TNK-tPA; wherein the cation exchange chromatography comprises Fractogel SO3 as a nary phase and a mobile phase, wherein the mobile phase is a mixture of L-Arginine, O-phosphoric acid and polysorbate-20; (vi) subjecting the eluate of step (v) to virus reduction filtration for removal of virus present; wherein virus filtration is carried out by polyethersulphone (PES) lter having a size in the range from 15-20 nm; and (vii) concentrating the sample of step (vi) to obtain TNK- tPA; n the yield of the process is more than 60% and purity of A obtained is more than 95% as ed by Size exclusion chromatography.

2. The process as claimed in claim 1, wherein the TNK-tPA purity is more than 95% by Size Exclusion Chromatography and wherein the other critical quality attributes are: No additional band other than principal band SDS PAGE observed Monomer (%) More than 95% Single Chain Content (%) More than 60 % Host cell n (HCP) (ppm) Less than 100 Host cell DNA (HCD) (ng/dose) Less than 10

3. The process as claimed in step (i) of claim 1, wherein the sodium phosphate is present in range from 20–40 mM, sodium chloride is t in range from 1.5–2 M and urea is present in range from 2–3 M; wherein the pH of the mobile phase is present in range from 7.2–7.4.

4. The process as claimed in claim 3, wherein the affinity chromatography-I provides 0.8 – 1.5 log reduction in host cell proteins.

5. The process as claimed in step (ii) of claim 1, wherein the sodium acetate is present in range from 5–15 mM, urea is present in range from 2–3 M and EACA is present in range from 0.1–0.2 mM; wherein the pH of the affinity chromatography-II mobile phase is in range of pH 4.5–5.

6. The process as claimed in claim 5, wherein the affinity tography-II results 1–1.5 log reduction in host cell proteins and 1–4 log reduction of viral nce.

7. The process as claimed in claim 5, wherein the affinity chromatography-II results more than 1.5 log reduction of Xenotropic Murine Leukemia Virus (XMuLV) and more than 4 log reduction of Pseudorabies (PRV).

8. The process as d in step (iii) of claim 1, wherein sodium caprylate is present in the range from 0.01% - 0.07% (w/v), ably in the range of 0.05%; n concentration of urea is present in the range of 2–3 M; wherein viral inactivation is conducted by holding the sample for a period from 40–80 minutes; wherein holding of the sample at a ature range from 20–30°C; wherein the pH is present in range from 4.3 to 4.7.

9. The process as claimed in claim 8, wherein the Low pH and chemical inactivation results in more than 5 log reduction of XMuLV and PRV.

10. The process as d in step (iv) of claim 1, wherein the phosphate buffer is present in range from 5–15 mM, MES- Hydrate is present in range from 2–20 mM, urea is present in range from 1–3 M and sodium chloride is present in range from 0.1 to 0.5 M; wherein the mobile phase pH is in the range from 6–9; wherein the affinity chromatography-III elution type is linear salt gradient; wherein the salt of this elution is sodium chloride in a range from 0.1–1.0 M sodium chloride.

11. The process as claimed in claim 10, wherein the affinity chromatography-III results 0.5–1 log reduction in host cell proteins and 2 – 4 log of viral clearance.

12. The process as claimed in claim 10, wherein the affinity chromatography-III results more than 4 log reduction with XMuLV and PRV and more than 3 log reduction with MMV and Reo 3 viruses.

13. The process as claimed in step (v) of claim 1, wherein the L-Arginine is t in range from 250-350 mM, O-phosphoric acid is present in range from .8% and polysorbate-20 is present in range from 0.04 to 0.05 %; and wherein the mobile phase pH is in range from 7.3–7.5.

14. The s as claimed in claim 13, wherein the cation exchange chromatography results more than 1 log viral nce with MMV and more than 0.5 log nce for host cell proteins.

15. The process as claimed in step (vi) of claim 1, wherein the virus filtration results more than 4 log reduction of XMuLV, more than 3 log reduction of PRV, more than 4 log reduction of Reo-3 and more than 4.5 log reduction of MMV.

16. The process as claimed in step (vii) of claim 1, wherein the filter is ultra filtration membrane; wherein the ultra filtration membrane is PES; wherein the size of ultra filtration membrane is in a range from 5-30 kDa, preferably the size of ultra filtration membrane is 10 kDa.

17. The process as claimed in claim 16, wherein the concentrate is TNK-tPA retentate.

18. A process as d in claim 1, wherein ic r current chromatography is used for Affinity chromatography-I.

19. A process as claimed in claim 1, wherein Inline conditioning approach is used for buffer and load preparation for Affinity chromatography-I, Affinity chromatography-II, Affinity tography-III (Mixed Mode Chromatography) and cation exchange chromatography. WO 63299