DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Status of the Claims
Claims 1-15 are pending and examined herein.
Claim Rejections - 35 USC § 102
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale or otherwise available to the public before the effective filing date of the claimed invention.
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claims 1-2 and 5-15 are rejected under 35 U.S.C. 102(a)(1) or 35 USC 102 (a)(2) as being anticipated by Elson et al. (WO 2013/088259) and evidenced by Hach (“Conductivity Standard Solution”, Product Number 2972226).
Regarding claim 1, Elson teaches methods of purifying antibodies using various
antibody-specific affinity media (Abstract).
Specifically, Elson teaches purification of two different proteins: monoclonal antibodies composed of two different light chains, one containing a kappa and the other a lambda light chain, that share a common heavy chain ([0002]). A bispecific monoclonal antibody (kappa-lambda-MAb) containing one kappa and one gamma light chains (single kappa chain is the only Protein L binding motif in this antibody) preferentially elutes from KappaSelect affinity resin over monospecific kappa-only-Mab (two kappa chains - two Protein L binding motifs), as the monospecific Mab presumably has a higher affinity to the resin owing to the presence of two kappa chains in the monospecific format as opposed to a single kappa chain in the kappa-lambda-MAb ([0016]).
Fig. 2 schematically demonstrates structural differences between kappa-only-Mab (mono-kappa) and kappa-lambda-Mab molecules, and Fig. 3C demonstrates differential elution of kappa-lambda-Mab and kappa-only-Mab. Elson teaches eluting at least two different proteins from a Protein L matrix by lowering a conductivity: mono-kappa-Mab and kappa-lambda-Mab mixture of antibodies (“kappa-lambda-body bispecific IgG antibody”) were purified using KappaSelect affinity chromatography media [0059]).
After column loading and a wash step with 50 mM Sodium Phosphate, 250 mM Sodium Chloride, a pH step-elution was performed using a 50 mM glycine buffer ([0060]). The conductivity of the 50 mM glycine elution buffer is lower than the combined conductivity of the wash buffer containing 50 mM Sodium Phosphate and 250 mM Sodium Chloride, therefore proteins were eluted by lowering a conductivity.
Regarding claim 2, Elson teaches one of the proteins which comprises a certain number of Protein L binding motifs is separated from the other protein(s) in the elution step. Fig. 3C demonstrates that the kappa-lambda-Mab (the protein containing one Protein L binding motif) eluted at approximately 26 min, while the mono-kappa-Mab (the protein containing two Protein L binding motifs) eluted at approximately 28-29 min. Elution at both pH values 2.5 and 3.0 resulted in a very good separation between the both Mab variants.
Regarding claims 5-6, Elson teaches one of the proteins is an antibody, and the antibody is a whole antibody or an antibody fragment. Specifically, both bispecific kappa-lambda-MAb and monospecific kappa-only-Mab are full-length monoclonal antibodies ([0016] and Fig. 1A-C schematically illustrate domain structures of these antibodies).
Regarding claim 7, Elson teaches the antibody is a monospecific antibody or a multispecific antibody. Elson teaches the bispecific kappa-lambda-MAb is a multispecific antibody, and kappa-only-Mab is a monospecific one ([0016]).
Regarding claim 8, Elson teaches two different proteins comprise:
(i) an antibody comprising two light chains, one of which comprises a Protein L binding motif, and the other of which comprises a Protein L non-binding motif – Elson teaches the bispecific kappa-lambda-Mab comprises one kappa as a Protein L binding motif and one lambda as a Protein L non-binding motif ([0016]), and
(ii) an antibody comprising two light chains, both of which comprise a Protein L binding motif – Elson teaches the monospecific kappa-only-Mab comprises two light chains, both of which comprise identical kappa sequences as Protein L binding motifs ([0016]).
Regarding claim 9, Elson teaches one of the proteins is eluted from the Protein L matrix at a conductivity between 0.01 and 16 mS/cm.
Specifically, Elson teaches antibody purification comprising a wash step with 50 mM sodium phosphate and 250 mM sodium chloride solution, and a pH step-elution performed using a 50 mM glycine buffer pH adjusted to pH 3.0 followed by pH 2.5 and pH 2.0 ([0060]). Glycine has a pKa value of 2.3. The Henderson–Hasselbalch equation teaches that at pH value equal to the pKa value 50% of all glycine buffer molecules will be charged, while the other 50% will remain neutral and will not contribute to solution conductivity. The pH values of 3.0, 2.5 or 2.0 recited in [0060] are around the 2.3 value of glycine pKa. That means that the conductivity of the 50 mM glycine buffer will correspond to a conductivity of a 25 mM glycine buffer concentration, which can be approximated by the conductivity of 25 mM NaCl solution. As evidenced by Hach (pg. 3, “Conductivity Standard Solution”, Product Number 2972226) 5.35 g of NaCl dissolved in 1 L of water give a solution with 1,000 microS/cm (or 1 mS/cm) conductivity. This solution has molar concentration of: 5.35 (g) /58.44 (NaCl molecular weight) = 0.092 M, or 92 mM concentration. Thus, 1 mS/cm conductivity corresponds to a concentration of 92 mM NaCl. The 25 mM glycine buffer approximately equivalent to 25 mM of NaCl, therefore, should have 0.37 mS/cm conductivity (92 mM – 1 mS/cm, 25 mM - 0.37 mS/cm).
The 0.37 mS/cm estimated conductivity of the 50 mM glycine buffer used to elute both the bispecific kappa-lambda-MAb and the monospecific kappa-only-Mab ([0016]) falls within the claimed range of 0.01 – 16 mS/cm. Even given the approximate nature of the calculations, this value is in the middle of the recited range, being 37 times higher than the lower limit of the range, and about 43 times lower than the upper limit.
Regarding claim 10, Elson teaches the conductivity is reduced in a stepwise manner during the elution step. Specifically, Elson teaches elution in example 1 performed in a stepwise manner: the column was washed with a sodium phosphate buffer, pH 7.0, then the proteins were eluted with a 50 mM glycine buffer, pH 3.0, 2.5 or 2.0 ([0060]).
Regarding claims 11-12, Elson teaches one of the proteins is eluted from the Protein L matrix at an acidic pH between 2.4 and 3.3. Specifically, Elson teaches elution of bispecific kappa-lambda-MAb and monospecific kappa-only-Mab in a stepwise manner at pH 3.0 or 2.5 ([0060] and Fig. 3C), wherein both pH values are acidic pH values and both fall within the range between 2.4 and 3.3 recited in claim 12.
Regarding claim 13, Elson teaches the pH remains constant or substantially unchanged during the elution step. Specifically, Elson teaches elution of both bispecific kappa-lambda-MAb and monospecific kappa-only-Mab in a stepwise manner at pH 3.0 or 2.5 ([0060] and Fig. 3C). The pH of the eluting buffer remained constant during the elution step.
Regarding claim 14, Elson teaches the method of producing a protein comprising the steps of:
(a) eluting at least two different proteins from a Protein L matrix by lowering a conductivity – Elson teaches elution of mono-kappa-Mab and kappa-lambda-Mab from KappaSelect affinity resin ([0016] and Fig. 3C); the limitation of elution by lowering conductivity is addressed above in details for claim 9; and
(b) collecting one of the eluted proteins, wherein each of the proteins comprises a different number of Protein L binding motifs - Elson teaches “the methods comprise the further step of determining the purity and proportions of the intact antibody in the eluted fraction” ([0023]) and “eluted fractions were collected and analyzed” [0060]. The kappa-lambda-Mab contains one Protein L binding motif, while the mono-kappa-Mab contains two Protein L binding motifs ([0016] and Fig. 2 middle panel).
Regarding claim 15, Elson teaches an antibody comprising a light chain, which comprises a kappa variable region and a lambda constant region (Fig. 1B).
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated 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 are summarized as follows:
Determining the scope and contents of the prior art.
Ascertaining the differences between the prior art and the claims at issue.
Resolving the level of ordinary skill in the pertinent art.
Considering objective evidence present in the application indicating obviousness or nonobviousness.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 3-4 are rejected under 35 U.S.C. 103 as being unpatentable over Elson, as applied to claim 1, in view of Nilson et al. (Journal of immunological methods vol. 164,1 (1993): 33-40).
Regarding claims 3-4, Elson teaches the method of purifying a protein comprising the step of eluting at least two different proteins from a Protein L matrix by lowering a conductivity, wherein each of the proteins comprises a different number of Protein L binding motifs ([0016]).
Elson fails to teach that the Protein L binding motif is an antibody kappa chain variable region, which belongs to human kappa subgroup 1 (VK1).
Nilson teaches purification of antibodies using protein L-binding framework structures in the light chain variable domain (Title). Nilson also teaches the Protein L binding motif is an antibody kappa chain variable region or a fragment thereof which has a binding ability to Protein L, and the antibody kappa chain variable region is human variable kappa subgroup 1 (VK1), and variants thereof.
Specifically, Nilson teaches “it binds to the framework region of the K chain VL domain, predominantly to the VK1, VKIII and VKIV subgroups” (pg. 34, Col. 1, par. 2).
It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to apply the method of Elson for purifying an antibody containing a human variable kappa subgroup 1 (VK1) sequence as taught by Nilson, as an obvious choice of selecting a Protein L binding motif from a limited number of known species: VK1, VKIII and VKIV subgroups (pg. 34, Col. 1, 2nd paragraph). One having ordinary skill in the art would have been motivated to combine these teachings because VK1 sequence is one of the three sequences having affinity to immobilized Protein L purification resins (Nilson, “protein L, binds Ig molecules regardless of heavy chain class, through interaction with Ig light chains”, pg. 34, Col. 1, 2nd paragraph). The use human VK1 sequence would have been desirable to those of ordinary skill in the art for designing monoclonal antibodies with decreased immunogenicity in humans.
One having ordinary skill in the art would have had a reasonable expectation of success in combining the prior art references because Nilson has already demonstrated the use of VK1 motif in antibody elution by lowering a conductivity (pg. 34, Col. 2, last paragraph).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Alexander Volkov whose telephone number is (571) 272-1899. The examiner can normally be reached M-F 9:00AM-5:00PM (EST).
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Bao-Thuy Nguyen can be reached on (571) 272-0824. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/ALEXANDER ALEXANDROVIC VOLKOV/
Examiner, Art Unit 1677
/REBECCA M GIERE/Primary Examiner, Art Unit 1677
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