DETAILED ACTION
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.
Claims 3, 15, 18, 20, 31, 32, 35, 42, 44, 68, 69, 72, 76, 78 and 85 are pending and under examination.
35 USC § 103(a) rejections withdrawn
The rejections of claims 3, 5, 20, 24, 27, 32, 35, 37, 60, 62-63, 67-69, 72, 76, 78 and 85 under 35 U.S.C. 103 as being unpatentable over Bertl et al (WO 2015/024896, published February 26, 2015) Von Kreudenstein et al (US 2012/0149876, published June 14, 2012) in view of Althouse et al. (WO 2015/070068, cited previously), in view of Schaefer et al (PNAS, 108:11187-11192, 2011, cited previously), Spiess et al. (Molecular Immunology 67 (2015) 95-100, cited previously), Choi et al. (Appl Microbiol Biotechnol, 64 (2004, cited previously), and Nti-gyabaah et al. (US 2014/0288278, cited previously) are withdrawn in view of Applicant’s amendments to claim 3.
The rejections of claims 3, 5, 15, 18, 20, 24, 27, 32, 35, 37, 44, 60, 62-63, 67-69, 72, 76, 78 and 85 under 35 U.S.C. 103 as being unpatentable over Bertl et al (US 10,316,059, issued June 11, 2019, filed February 19, 2016) Von Kreudenstein et al (US 2012/0149876, published June 14, 2012) in view of Althouse et al. (WO 2015/070068, cited previously), in view of Schaefer et al. (PNAS, 108:11187-11192, 2011, cited previously), Spiess et al. (Molecular Immunology 67 (2015) 95-100, cited previously), Choi et al. (Appl Microbiol Biotechnol, 64 (2004, cited previously), and Nti-gyabaah et al. (US 2014/0288278, cited previously) and further in view of Falkenstein et al. (US 2013/0217866, cited previously), Johansson et al. (US 2007/0167613, cited previously) and Arakawa et al. (US 2014/0072560, cited previously) are withdrawn in view of Applicant’s amendments to claim 3.
The rejections of claims 3, 5, 20, 24, 26-28, 30-32, 35, 37, 42, 60, 62-63, 67-69, 72, 76, 78 and 85 under 35 U.S.C. 103 as being unpatentable over Bertl et al (US 10,316,059, issued June 11, 2019, filed February 19, 2016, cited previously) Von Kreudenstein et al (US 2012/0149876, published June 14, 2012, cited previously) in view of Althouse et al. (WO 2015/070068, cited previously), in view of Schaefer et al. (PNAS, 108:11187-11192, 2011, cited previously), Spiess et al. (Molecular Immunology 67 (2015) 95-100, cited previously), Choi et al. (Appl Microbiol Biotechnol, 64 (2004, cited previously), and Nti-gyabaah et al. (US 2014/0288278, cited previously) in further view of Gagnon (US 2015/0376231, cited previously)), Behrens et al. (US 2011/0318757, cited previously), Bian et al. (US 2011/0105730, cited previously), Hickman et al. (US 2015/0344564, cited previously) and Mahajan et al. (US 2015/0093800, cited previously) are withdrawn in view of Applicant’s amendments to claim 3.
NEW REJECTIONS:
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
Claims 3, 15, 18, 20, 31, 32, 35, 42, 44, 68, 69, 72, 76, 78 and 85 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. These are new matter rejections.
The limitation “adjusting the mixed mode anion chromatography eluate to about pH 5.5 and subjecting the mixed mode anion chromatography eluate to a mixed mode cation chromatography carried out in bind-and-elute mode to generate a mixed mode cation chromatography eluate is not supported in the specification as filed.
The specification recites “The half-antibody pools obtained from the protein A chromatography step were then combined in a 1: 1 molar ratio, the pH was adjusted to pH 8 .2. 200 mM L-glutathione (91/9% GSH/GSSG) buffer was added to the combined pools to achieve a ratio of 165 moles of L-glutathione for every 1 mole of bispecific being formed. The material was heated to 32.0 ± 2.0°C for 8 - 24 hours. The resulting assembled pool was cooled to 15 - 25°C and then adjusted to pH 5.5. The pH adjusted assembled pool was then subjected to a multimodal cation exchange chromatography using Capto™ MMC resin in a bind and elute mode. The column was equilibrated with 100 mM sodium acetate, pH 5.5. (paragraph 434).
The specification further recites “The pool from Capto L chromatography step containing a first Fab' half-molecule (Fab' A) was adjusted to pH 5.5. DPDS (Dipyridyl disulfide) was added to the pH 5.5 adjusted Capto L pool” (paragraph 443).
The specification recites “The mixed mode resins provided the best separation of the F(ab')2 from the product related impurities under the experimental conditions. CaptoTM MMC contour plots showed that Capto™ MMC was predicted to separate the F(ab')2 from its product-specific impurities effectively at pH 5.5 (paragraph 447). Capto MMC is a mixed mode cation chromatography resin. Capto L is a protein A chromatography resin.
Thus the limitation of the amended claims “adjusting the mixed mode anion chromatography eluate to about pH 5.5” is not supported by the specification
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103(a) which forms the basis for all obviousness rejections set forth in this Office action:
(a) A patent may not be obtained though the invention is not identically disclosed or described as set forth in section 102 of this title, if the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art to which said subject matter pertains. Patentability shall not be negatived by the manner in which the invention was made.
The factual inquiries set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied for establishing a background for determining obviousness under 35 U.S.C. 103(a) are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 3, 20, 31, 32, 35, 68, 69, 72, 76, 78 and 85 are rejected under 35 U.S.C. 103 as being unpatentable over Bertl et al (WO 2015/024896, published February 26, 2015) Von Kreudenstein et al (US 2012/0149876, published June 14, 2012) in view of Althouse et al. (WO 2015/070068, cited previously), in further view of Monck et al (US 2018/0251539, published September 6, 2018, effective filing date August 24, 2015), O’Connor et al (US 2016/0251441, published September 1, 2016, filed October 23, 2014), Schaefer et al (PNAS, 108:11187-11192, 2011, cited previously), Spiess et al. (Molecular Immunology 67 (2015) 95-100, cited previously), and Nti-gyabaah et al. (US 2014/0288278, cited previously).
Bertl disclose purification of knob-in-hole (KiH) bispecific antibodies using anion and cation exchange chromotography as well as mixed mode chromatography (page 14, 3rd paragraph). Bertl disclose that KiH technology was well known in the art (page 10, 2nd paragraph to page 14, 2nd paragraph; page 29, 2nd paragraph).
Von Kreudenstein disclose purifying KiH bispecific antibodies using anion or cation exchange columns to a purity level of greater than 95% (paragraphs 12-20, 79-80, 93, 158, 232-235). Von Kreudenstein disclose mammalian cell systems including CHO cells (paragraphs 223, 229).
Thus, purification of KiH antibodies using different purification methods to reach high levels of purity were well known in the art.
Neither Bertl nor Von Kreudenstein specifically disclose purification of KiH bispecific antibodies using mixed mode anion chromatography and mixed mode cation chromatography.
Althouse discloses a method of purifying antibodies including bispecific antibodies such that the resulting antibody composition is substantially free of product-related impurities including aggregates that includes the steps of subjecting the primary recovery sample to an affinity chromatographic support such as a Protein A resin, which is considered “a capture chromatography” of step (a), and the Protein A column is then eluted using an appropriate elution buffer. (paragraphs 5, 63, 66, 93 and 110). Althouse disclose that the flow-through were collected and measured for protein concentrations by UV 280 (paragraph 121, 130, 132, 135). Althouse further discloses that the Protein A eluted fraction is then subjected to further polishing through two mixed mode chromatography steps such as a cation exchange mixed mode step followed by an anion exchange mixed mode step or vice versa (paragraphs 6-7, 80, 95). Althouse disclose that the overall charge of the antibody determines how well the antibody binds to the mixed mode columns (paragraph 75). Althouse disclose that antibodies, which generally have an overall positive charge in the buffer pH below its pl, will bind well to cation exchange material, which contain negatively charged functional groups (Id). Althouse further discloses a step of subjecting the second mixed mode eluate to ultrafiltration. (paragraph 56). Althouse discloses that the Protein A column can be equilibrated with a suitable buffer prior to sample loading at a pH of about 7.2, (paragraphs 6 and 66). Althouse discloses that following loading of the Protein A column, the column can be washed with the equilibrating buffer (paragraphs 17 and 18).
Althouse discloses that examples of anion exchange mixed mode resins include Capto Adhere and Capto Adhere ImpRes, which include an amine ligand with an aromatic moiety and that the Capto Q ImpRes ligand has a high ion-exchange capacity due to a quaternary amine. Althouse teaches that examples of anion exchange mixed mode resins include Capto Adhere having a N-benzyl-N-methyl ethanol amine”.
Althouse discloses that by using a combination of Capto MMC, which is the CEX MM, and Capto Adhere resin, which is the MM AEX, percentage aggregates were below 1% (see Table 4). Althouse further discloses that the mixed mode columns can be loaded to up to 1200 g/L proteins and that after feed load, the column is washed with the equilibration buffer which is a buffer such as Tris buffer at pH 7 (page 21, line 31; page 22 lines 3-4). Althouse discloses suitable mammalian hosts including CHO cells.
In addition, Althouse discloses that to express the antibody of the invention DNA encoding partial or full-length light and heavy chains are inserted into one or more expression vectors and then expressed in suitable mammalian host cells (paragraphs 51-52).
One of ordinary skill in the art would have been motivated to apply Althouse’s methods for purification of bispecific antibodies using mixed mode anion chromatography and mixed mode cation chromatography with Bertl and Von Kreudenstein method for purifying KiH bispecific antibodies because Bertl disclose purification of knob-in-hole (KiH) bispecific antibodies using anion and cation exchange chromotograpy as well as mixed mode chromatography. Furthermore, Nti-gyabaah disclose that mixed mode chromatography media provide unique selectivities that cannot be reproduced by single mode chromatography methods such as ion exchange (paragraph 87). Nti-gyabaah disclose both Capto AdhereTM and Capto MMCTM mixed mode resins (paragraphs , 89, 121).
Neither Bertl, Von Kreudenstein nor Althouse disclose holding both the first capture eluate and the second capture eluate for a minimum of 120 minutes at pH< 3.6 or adjusting the mixed mode anion chromatography eluate to about pH 5.5.
Monck disclose a 15 to 240 minute treatment period at a pH of about 3.3 to 3.7 to eluates from a protein A column (paragraph 213).
O’Connor disclose that the pH of the recombinant antibody solution can be adjusted to a more neutral pH, for example, between about 4.5 to about 8.5, or between about 4.5 and about 5.5 prior to continuing the purification process (paragraph 100). O’Connor disclose that eluted antibody was detected using UV absorbance at 280 nm (paragraph 113).
One of ordinary skill in the art would have been motivated to apply Monck’s 15 to 240 minute treatment period at a pH of about 3.3 to 3.7 and O’Connor’s recombinant antibody solution at ph between about 4.5 and about 5.5 to Bertl, Von Kreudenstein and Althouse’s method for method of purifying KiH bispecific antibodies because Bertl, Von Kreudenstein, Althouse, Monck and O’Connor disclose methods for purifying antibodies using protein A columns and ion exchange chromotography.
Neither Bertl, Von Kreudenstein, Althouse, Monck and O’Connor specifically disclose that a first arm comprising a VH/VL unit binding a first epitope and a second arm comprising a VH/VL unit binding a second epitope are produced separately.
Schaefer discloses production of the bispecific antibodies in cells from four expression plasmids at equimolar ratios, followed by purification using a protein A affinity chromatography followed by size-exclusion chromatography (page 11188, 2nd column). Schaefer further discloses that side products which need to be reduced during purification include half antibodies as well as antibodies lacking one light chain which are considered fragments as well as heavy-chain dimers and tetramers, (page 11189).
Spiess discloses that engineering antibody heavy chains for heterodimerization has emerged as a successful strategy to overcome the BsIgG heavy chain-pairing problem and that heavy chains were first engineered for heterodimerization in the 1990s using a “knobs-into-holes” strategy (section 2.1.1). Spiess discloses the most widely used route to BsIgG is by separate expression of the component antibodies in two different host cells followed by purification and assembly into BsIgG in vitro (section 2.1.2).
One of ordinary skill in the art would have been motivated to apply Schaefer and Spiess’s method of purifying bispecific antibodies using separate production of the two arms to Bertl, Von Kreudenstein, Althouse, Monck and O’Connor’s method of purifying KiH bispecific antibodies because Schaefer, Spiess, O’Connor, Bertl, Von Kreudenstein and Althouse all involve the purification of bispecific antibodies.
It would have been prima facie obvious to combine Bertl, Von Kreudenstein, Althouse, Monck and O’Connor’s method of purifying KiH bispecific antibodies with Schaefer and Spiess’s method of purifying bispecific antibodies using separate production of the two arms to have a method for purifying a KiH bispecific antibody from a composition comprising the KiH bispecific antibody and antibody homodimer impurities, wherein the KiH bispecific antibody comprises a first arm comprising a VH/VL unit binding a first epitope and a second arm comprising a VH/VL unit binding a second epitope, and wherein the first arm and the second arm are produced separately using a mammalian cell, the method comprising the sequential steps of subjecting the first arm of the KiH bispecific antibody and the second arm of the KiH bispecific antibody, separately, to protein A chromatography to produce a first capture eluate and a second capture eluate, holding both the first capture eluate and the second capture eluate for a minimum of 120 minutes at pH< 3.6, inactivating virus via a pH viral inactivation technique, forming a mixture comprising the first and the second capture eluates of each arm of the KiH bispecific antibody and adjusting pH to about pH 8.2, wherein said forming a mixture produces the composition comprising the KiH bispecific antibody and the antibody homodimer impurities; wherein the conditions sufficient to produce the composition include the presence of a reducing agent, subjecting the composition comprising the KiH bispecific antibody and the antibody homodimer impurities to a mixed mode anion chromatography carried out in flow-through mode to generate a mixed mode anion chromatography eluate, wherein the mixed mode anion chromatography comprises a quaternary amine and a hydrophobic moiety, or wherein the mixed mode anion exchange chromatography comprises an N-benzyl-n-methyl ethanolamine, adjusting the mixed mode anion chromatography eluate to about pH 5.5 and subjecting the mixed mode anion chromatography eluate to a mixed mode cation chromatography carried out in bind-and-elute mode to generate a mixed mode cation chromatography eluate, wherein the mixed mode cation chromatography comprises a carboxylic acid group and a hydrophobic moiety, and collecting a fraction of the mixed mode cation chromatography eluate comprising the KiH bispecific antibody and an amount of antibody homodimer impurities reduced by more than 50%, wherein the fraction contains no more than 5% antibody homodimer impurities of total antibody species, and wherein reduced amount of antibody homodimer impurities is reduced by more than 50%.
One of ordinary skill in the art would have had a reasonable expectation of success because Von Kreudenstein discloses that a high level of purity of the bispecific heterodimers may be achieved using the knob-in-hole technology while Nti-gyabaah disclose the advantages of using mixed mode chromatography.
Thus, the art disclose all the claimed steps for purifying KiH bispecific antibodies of the present claims. With regard to the various purification steps using the listed purification reagents, these purification steps are clearly result effective parameters that a person of ordinary skill in the art would routinely optimize. Optimization of parameters is a routine practice that would be obvious for a person of ordinary skill in the art to employ. It would have been customary for an artisan of ordinary skill to determine the optimal amount of each ingredient needed to achieve the desired results. One of ordinary skill in the art would expect to obtain similar levels of antibody homodimer impurities by following the same scheme taught by Althouse, Schaefer, Spiess and at least in absence of evidence to the contrary.
The principle of law states from MPEP 2144.05: "The normal desire of scientists or artisans to improve upon what is already generally known provides the motivation to determine where in a disclosed set of percentage ranges is the optimum combination of percentages."(Peterson, 315 F.3d at 1330, 65 USPQ2d at 1382); Generally, differences in concentration or temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical. "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). The steps for the purification of bispecific antibodies including KiH bispecific antibodies have been well documented and differ for the purification of different bispecific antibodies. Thus, absent some demonstration of unexpected results from the claimed parameters, the optimization of ingredient amounts would have been obvious at the time of applicant's invention.
Claims 3, 15, 18, 20, 31, 32, 35, 42, 44, 68, 69, 72, 76, 78 and 85 are rejected under 35 U.S.C. 103 as being unpatentable over Bertl et al (US 10,316,059, issued June 11, 2019, filed February 19, 2016) Von Kreudenstein et al (US 2012/0149876, published June 14, 2012) in view of Althouse et al. (WO 2015/070068, cited previously), Monck et al (US 2018/0251539, published September 6, 2018, effective filing date August 24, 2015), O’Connor et al (US 2016/0251441, published September 1, 2016, filed October 23, 2014), Schaefer et al. (PNAS, 108:11187-11192, 2011, cited previously), Spiess et al. (Molecular Immunology 67 (2015) 95-100, cited previously), and Nti-gyabaah et al. (US 2014/0288278, cited previously) and further in view of Falkenstein et al. (US 2013/0217866, cited previously), Johansson et al. (US 2007/0167613, cited previously) and Arakawa et al. (US 2014/0072560, cited previously).
The prior art teachings of Bertl, Von Kreudenstein, Althouse, Schaefer, Monck, O’Connor and Spiess are discussed supra.
Neither Bertl, Von Kreudenstein, Althouse, Schaefer, Monck, O’Connor nor Spiess disclose that the KiH bispecific antibody elution from the mixed mode cation chromatography is a gradient elution, a step elution, and by pH gradient and salt gradient.
Falkenstein discloses purification of an antibody using Capto MMC, which is a mixed mode cation exchange media (abstract). Falkenstein teaches that the chromatography was performed with a leaner elution gradient ( paragraph 135).
Johansson teaches purification of antibodies using multi-modal cation exchange which includes elution of the antibodies by a pH step, using 25 mM phosphate buffer, pH 7.5 ( paragraph 82).
Arakawa teaches mixed mode chromatography such as MMC for separating proteins such as etanercept (abstract; paragraphs 17-18). Arakawa discloses that once a protein analyte has become bound to the column and elution step is conducted to release the bound analyte from the column using a salt gradient applied preferably in a gradient of increasing concentration ( paragraph 30). Arakawa exemplified using Na2SO4 gradient at pH 7.5 (“pH gradient and salt gradient”) (paragraphs 45, 49).
One of ordinary skill in the art would have been motivated to apply Falkenstein, Johansson and Arakawa method of purifying proteins by performing CEX MM elution using gradient or step or both pH and salt gradients to Bertl, Von Kreudenstein, Althouse, Monck, O’Connor, Schaefer, Spiess method for purifying KiH bispecific antibodies because Bertl, Von Kreudenstein, Althouse, Schaefer, Spiess, O’Connor, Falkenstein and Johansson involve the purification of bispecific antibodies while Arakawa disclose the purification of protein. Thus, all the references involve the purification of proteins using ion exchange chromatography. In addition, Bertl, Althouse, Falkenstein, Johansson and Arakawa disclose the use of mixed mode chromatography in the purification of proteins, including bispecific antibodies. It would have been obvious to one of ordinary skill in the art at the time the invention was made to have included for elution of a KiH bispecific antibody from a CEX mixed mode chromatography in a KiH bispecific antibody protein purification scheme which includes a AEX followed by an CEX as taught by Althouse, Schaefer, Spiess and an elution mode which includes a gradient, step or both by pH gradient and salt gradient. It would have been obvious to one of skill in the art to look for different parameters in the use of mixed mode chromatography for the purification of bispecific antibodies. As stated previously, optimization of parameters is a routine practice that would be obvious for a person of ordinary skill in the art to employ. Absent unexpected results it would have been obvious to have a method for purifying a KiH bispecific antibody from a composition comprising the KiH bispecific antibody and antibody homodimer impurities, wherein the KiH bispecific antibody comprises a first arm comprising a VH/VL unit binding a first epitope and a second arm comprising a VH/VL unit binding a second epitope, and wherein the first arm and the second arm are produced separately using a mammalian cell, the method comprising the sequential steps of subjecting the first arm of the KiH bispecific antibody and the second arm of the KiH bispecific antibody, separately, to protein A chromatography to produce a first capture eluate and a second capture eluate, holding both the first capture eluate and the second capture eluate for a minimum of 120 minutes at pH< 3.6, inactivating virus via a pH viral inactivation technique, forming a mixture comprising the first and the second capture eluates of each arm of the KiH bispecific antibody and adjusting pH to about pH 8.2, wherein said forming a mixture produces the composition comprising the KiH bispecific antibody and the antibody homodimer impurities; wherein the conditions sufficient to produce the composition include the presence of a reducing agent, subjecting the composition comprising the KiH bispecific antibody and the antibody homodimer impurities to a mixed mode anion chromatography carried out in flow-through mode to generate a mixed mode anion chromatography eluate, wherein the mixed mode anion chromatography comprises a quaternary amine and a hydrophobic moiety, or wherein the mixed mode anion exchange chromatography comprises an N-benzyl-n-methyl ethanolamine, adjusting the mixed mode anion chromatography eluate to about pH 5.5 and subjecting the mixed mode anion chromatography eluate to a mixed mode cation chromatography carried out in bind-and-elute mode to generate a mixed mode cation chromatography eluate, wherein the mixed mode cation chromatography comprises a carboxylic acid group and a hydrophobic moiety, and collecting a fraction of the mixed mode cation chromatography eluate comprising the KiH bispecific antibody and an amount of antibody homodimer impurities reduced by more than 50%, wherein the fraction contains no more than 5% antibody homodimer impurities of total antibody species, wherein the KiH bispecific antibody elution from the mixed mode cation chromatography is a gradient elution, a step elution, and by pH gradient and salt gradient.
Relevant Arguments to previous rejections.
Applicant argues that the references combined do not teach or suggest use of mixed-mode anion exchange chromatography in flow-through mode followed by mixed-mode cation exchange chromatography in bind-and-elute mode. Applicant argues that Althouse suggests only flow-through mode. Applicant further argues that Nti-gyabaah suggests only a flow-through recovery methodology for any column.
Applicant argues that the combined references also do not teach or suggest that the use of mixed-mode anion exchange chromatography in flow-through mode followed by mixed-mode cation exchange chromatography in bind-and-elute mode would be useful for purification of KiH bispecific antibodies where the two halves of the antibodies are separately produced and separately purified by Protein A chromatography, then reassembled. Applicant argues that Althouse appears to only disclose the purification of antibodies produced as whole antibodies; Applicant argues that this would reduce
the number of antibody fragments and there is nothing in Althouse to suggest that the
methodology of those Examples would work for reassembled half-antibodies. Applicant argues that Bertl discloses purification of half antibodies, but, again, only in the context of using hydroxyapatite. Applicant argues that Speiss disclose that bispecific antibodies could be produced as half antibodies, then reassembled to a full bispecific antibody, but says nothing about how those antibodies would be purified.
Applicant’s arguments have been considered but are not persuasive. As stated previously, in response to applicant's arguments against Bertl, Von Kreudenstein, Althouse, Schaefer, Monck, O’Connor and Spiess individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986). All the claim limitations were in the prior art and there was ample motivation to combine the references. Furthermore, the transitional term “comprising”, in the present claims is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. See, e.g., > Mars Inc. v. H.J. Heinz Co., 377 F.3d 1369, 1376, 71 USPQ2d 1837, 1843 (Fed. Cir. 2004) (“like the term comprising,’ the terms containing’ and mixture’ are open-ended.”).< Invitrogen Corp. v. Biocrest Mfg., L.P., 327 F.3d 1364, 1368, 66 USPQ2d 1631, 1634 (Fed. Cir. 2003). MPEP 2111.02. In addition, a prior art reference is relevant for all its teachings, not only its examples. Merck & Co. v. Biocraft Labs., Inc., 874 F.2d 804, 807 (Fed. Cir. 1989) (holding that both preferred and unpreferred embodiments must be considered). In addition, Applicants point to narrow embodiments which are not the sum total of information conveyed by each. Art is art, not only for what it expressly teaches, but also for what it would reasonably suggest to the skilled artisan, including alternative or non-preferred embodiments. MPEP § 2123.
Althouse disclose that the antibodies may be bispecific (paragraphs 110, 111). Althouse discloses that to express the antibody of the invention DNA encoding partial or full-length light and heavy chains may be inserted into more than one expression vector. Thus, Althouse disclose that the first arm and the second arm of the bispecific antibody may be produced separately. Schaefer discloses production of the bispecific antibodies in cells from four expression plasmids at equimolar ratios, followed by purification using a protein A affinity chromatography. Schaefer disclose heavy chain 1 and heavy chain 2 as separate chains (Figure 1). As Applicant discloses, Bertl discloses purification of half antibodies, albeit not using the protein A column and that Speiss disclose that bispecific antibodies could be produced as half antibodies, then reassembled to a full bispecific antibody. Given the teachings of Althouse, Speiss, Schaefer and Bertl that half antibodies may be produced and then reassembled to a full bispecific antibody and that purification of antibodies is achieved using protein A columns, it would have been obvious to purify the separate arms on a protein A column before forming a mixture of the first arm and the second arm of the bispecific antibody.
Furthermore, for a particular KiH bispecific antibody it would have been obvious to utilize protein A column followed by mixed mode anion chromatography using well-known mixed mode anion resins followed by mixed mode cation chromatography using well-known mixed mode anion resins. As stated previously, optimization of parameters is a routine practice that would be obvious for a person of ordinary skill in the art to employ. All of the claim limitations are present in the art as well as a motivation to combine the individual references. Absent unexpected results, it would have been obvious to purify a KiH bispecific antibody using the claimed methods.
In addition, Applicant argues that the Office Action states that the present claims represent mere optimization and not inventive activity. Applicant argues that the claims of the instant application are based on, at least in part, the surprising finding that the specific order and configuration of the steps recited in the amended claims results in significantly improved purification of KiH bispecific antibodies from a composition comprising said KiH bispecific antibody and antibody homodimer impurities. Example 1 and the experiments described therein demonstrate that the purification scheme depicted in FIG. 1A achieved significantly better separation of aX1/Y1 bispecific antibody from product-related impurities, such as homodimer impurities, as compared to the purification schemes in FIG. 1B or FIG. 1C. For example, as reported in Example 1, samples spiked with 20% homodimers were purified to reduce the level of homodimer impurities to below 2% for a mass spectrometry-based assay and below the limit of quantification for a cell-based assay. Applicant argues that the methodology of the amended claims is not an optimization of parameters, but rather reflects the discovery of a new purification platform useful for significantly reducing antibody homodimer impurities in KiH bispecific antibody compositions. Applicant argues that such findings are strong evidence of the non-obviousness of the amended claims, especially in view of the known challenges associated with purifying homodimer impurities away from KiH bispecific antibodies.
Applicant further argues that the cited references experimentally disclose purification of already-assembled whole antibodies rather than antibodies separately produced and then assembled during the purification process: Bertl (whole EGFR/IGFR bispecific antibody; whole Ang2/VEGF bispecific antibody; whole TWEAK/ILl 7 bispecific antibody); von Falkenstein (whole HER2/neu bispecific antibody); Althouse (two unidentified antibodies, mAbl and mAb3); Schaefer (3 whole bispecific antibodies); Spiess (only mentions that half antibodies can be separately produced and assembled, but provides no details as to purification steps); Nti-gyabaah (whole adalimumab, whole anti-TNF antibody; Gagnon (whole HER2 antibody, whole unidentified IgM, whole unidentified IgG); Behrens (whole MUCl antibodies); Bian (whole unidentified IgG); Hickman (whole IL8 antibodies; whole IL12 antibodies); Mahajan (whole unidentified mAbl and mAb2); Falkenstein (while IGF-lR antibody, whole anti-IL13R antibody); Johansson (whole unidentified IgG1); Arakawa (whole etanercept). Applicant argues as such, the references together do not teach or suggest the claimed purification method. Indeed, the range of purification methods disclosed in the cited references evidences not that the presently claimed invention was routine optimization, but that its development was inventive activity.
Applicant’s arguments have been considered but are not persuasive. As previously disclosed, the purification of antibodies, including bispecific antibodies is a well-developed area. There are hundreds of research articles and patents on purifying bispecific antibodies. The exact parameters used are the result of optimization for the purification of the antibodies. As stated above, optimization of parameters is a routine practice that would be obvious for a person of ordinary skill in the art to employ. As indicated above, all the claim limitations were in the prior art and there was ample motivation to combine the references. Absent unexpected results it would have been obvious to use the claimed chromatographic methods and specific parameters to purify bispecific antibodies. Furthermore, the specific parameters used to optimize the purification methods would likely be specific to the particular bispecific antibody purified.
As indicated above, purifying KiH bispecific antibodies using anion or cation exchange columns to a purity level of greater than 95% while Nti-gyabaah disclose that mixed mode chromatography media provide unique selectivities that cannot be reproduced by single mode chromatography methods such as ion exchange. Given the superior qualities of mixed mode chromotography it would have been obvious to use two common mixed chromatography Capto Adhere® and Capto MMC™ to purify the bispecific antibodies from their homodimeric antibodies. Methods for purifying bispecific antibodies including KiH bispecific antibodies were known in the art were well in the art and involve many different chromatographic methods which may be dependent on the particular bispecific antibody that is being purified. Mixed mode chromatography to purify antibodies including KiH antibodies was well known in the art. Given the vast amount of information involving the purification of bispecific antibodies at the time the application was filed, unexpected results for purifying bispecific antibodies must be sufficiently commensurate in scope with the variables involved in the purification process.
As recited earlier, MPEP 716.02(d) states
Whether the unexpected results are the result of unexpectedly improved results or a property not taught by the prior art, the “objective evidence of nonobviousness must be commensurate in scope with the claims which the evidence is offered to support.” In other words, the showing of unexpected results must be reviewed to see if the results occur over the entire claimed range. In re Clemens, 622 F.2d 1029, 1036, 206 USPQ 289, 296 (CCPA 1980) (Claims were directed to a process for removing corrosion at “elevated temperatures” using a certain ion exchange resin (with the exception of claim 8 which recited a temperature in excess of 100C). Appellant demonstrated unexpected results via comparative tests with the prior art ion exchange resin at 110C and 130C. The court affirmed the rejection of claims 1-7 and 9-10 because the term “elevated temperatures” encompassed temperatures as low as 60C where the prior art ion exchange resin was known to perform well. The rejection of claim 8, directed to a temperature in excess of 100C, was reversed.). See also In re Peterson, 315 F.3d 1325, 1329-31, 65 USPQ2d 1379, 1382-85 (Fed. Cir. 2003) (data showing improved alloy strength with the addition of 2% rhenium did not evidence unexpected results for the entire claimed range of about 1-3% rhenium); In re Grasselli, 713 F.2d 731, 741, 218 USPQ 769, 777 (Fed. Cir. 1983) (Claims were directed to certain catalysts containing an alkali metal. Evidence presented to rebut an obviousness rejection compared catalysts containing sodium with the prior art. The court held this evidence insufficient to rebut the prima facie case because experiments limited to sodium were not commensurate in scope with the claims.).
Example 1 discloses the purification of one KiH bispecific antibody. Althouse disclose that the overall charge of the antibody determines how well the antibody binds to the mixed mode columns (paragraph 75). Goyon et al ( J Chromotography B 1065-1066: 119-128, 2017) discloses that the isolelectric point of 25 therapeutic antibodies varied from 6.1 to 9.4 (Abstract; Fig 1, Table 2). It appears that the results demonstrated in the Examples is just the results for the optimization of a purification protocol for two related bispecific antibodies and not unexpected results. Thus, the purification scheme for two related KiH bispecific antibodies may not be the optimal purification scheme for other KiH bispecific antibodies and is not sufficient to demonstrate unexpected results for all KiH bispecific antibodies. Given that the isoelectric point of a specific KiH bispecific antibody would likely determine the ability of that antibody to bind to mixed mode chromatographic resin and the vast difference in isoelectric points of antibodies, it is unlikely that the purification scheme for one antibody would be applicable for other KiH bispecific antibodies with different isoelectric points. The unexpected results described by Applicants are not commensurate in scope with the breadth of the claims as currently presented. It is not clear if the unexpected results can be applied to all KiH bispecific antibodies, which is a very broad class of antibodies.
Summary
Claims 3, 15, 18, 20, 31, 32, 35, 42, 44, 68, 69, 72, 76, 78 and 85 stand rejected.
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/MARK HALVORSON/ Primary Examiner, Art Unit 1646