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 .
Claim Status
Claims 7-8, 10, and 13-15 have been cancelled; claims 1, 4-5, and 11-12 have been amended; and, claims 16-24 have been newly added, as requested in the amendment filed on 03/18/2026. Following the amendment, claims 1-6, 9, 11-12, and 16-24 are pending in the instant application.
Claims 1-6, 9, 11-12, and 16-24 are under examination in the instant office action.
Priority - Updated
Applicant’s claim for the benefit of a prior-filed application under 35 U.S.C. 119(e) or under 35 U.S.C. 120, 121, 365(c), or 386(c) is acknowledged.
Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55. Furthermore, it is noted that an English translation of the foreign priority document has been provided, and as such the claim to foreign priority has been perfected.
Claims 1-6, 9, 11-12, and 16-24 have an effective filing date of March 25, 2020 corresponding to CN202010219311.2.
Specification - Objections Withdrawn
Applicant has submitted an amended abstract that is between 50 and 150 words in length and has submitted a substitute specification wherein trade names and/or marks used in commerce are properly represented. As such, the objections to the specification are withdrawn.
Claim Objections - Withdrawn
Claims 1 and 13 were objected to for typographical errors. Applicant has amended claim 1 to remove any reference to L3. Claim 13 has been cancelled, rendering the objection moot. As such, the objections to claims 1 and 13 are withdrawn.
Claims 11 and 12 were objected to for reciting the abbreviation “TCEP” without spelling out the abbreviation at the first occurrence in the claims. Claim 12 was further objected to for reciting the abbreviation “EDTA” without spelling out the abbreviation at the first occurrence in the claims. Claim 4 has been amended to recite “ethylenediaminetetraacetic acid (EDTA)” and claim 5 has been amended to recite “tris(2-carboxyethyl)phosphine (TCEP)”. As such the abbreviation of EDTA and/or TCEP as recited in claims 11 and 12 are properly spelled out at the first occurrence in preceding claims 4 and 5, respectively. The objections to claims 11 and 12 are withdrawn.
Claim Rejections - 35 USC § 112 - Withdrawn
Claims 1-7, 9-10, and 13-14 rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for the recitation of “optionally further substituted with one or more substituents” in claims 1 and 13, wherein claims 2-7, 9-10, and 14 were included for being dependent upon and/or incorporating claim 1. Claim 13 has been cancelled, rendering its rejection moot. Claim 1 has been amended to remove W and L3 from claim 1, and has therefore removed the recitation of “optionally further substituted with one or more substituents”. In view of the instant claim amendments and the cancellation of claim 13, the rejection of claims 1-7, 9-10, and 13-14 under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite is withdrawn.
Claim Rejections - 35 USC § 103 - Withdrawn
Claims 7-8 were rejected under 35 U.S.C. 103 as being unpatentable over US 2015/0297748 A1 (previously cited on PTO-892; herein after referred to as "Masuda"), CN 112125915 A (original document published Dec. 2020; using US equivalent US 2022/0411436 A1 for translation; previously cited on PTO-892; herein after referred to as “Zhu”) and Talele (J. Med. Chem., 2016, 59, 8712-8756; previously cited on PTO-892; herein after referred to as “Talele”).
Claims 7-8 have been cancelled, rendering their rejection moot. As such, the rejection of claims 7-8 under 35 U.S.C. 103 as being unpatentable over Masuda, Zhu, and Talele is withdrawn.
Claims 10 and 13-15 were rejected under 35 U.S.C. 103 as being unpatentable over US 2015/0297748 A1 (previously cited on PTO-892; herein after referred to as "Masuda"), CN 112125915 A (original document published Dec. 2020; using US equivalent US 2022/0411436 A1 for translation; previously cited on PTO-892; herein after referred to as “Zhu”) and Talele (J. Med. Chem., 2016, 59, 8712-8756; previously cited on PTO-892; herein after referred to as “Talele”), as applied to claims 1-5 and 7-9, and in further view of non-patent literature by Abdollahpour-Alitappeh et. al. (Iran. Biomed. J., 2017, 21(4), 270-274; previously cited on PTO-892; herein after referred to as “Alitappeh”).
Claims 10 and 13-15 have been cancelled, rendering their rejection moot. As such, the rejection of claims 10 and 13-15 under 35 U.S.C. 103 as being unpatentable over Masuda, Zhu, Talele, and Alitappeh is withdrawn.
Claims 7-8 were rejected under 35 U.S.C. 103 as being unpatentable over US 2015/0297748 A1 (previously cited on PTO-892; herein after referred to as "Masuda") in view of non-patent literature by Talele (J. Med. Chem., 2016, 59, 8712-8756; previously cited on PTO-892; herein after referred to as “Talele”) and non-patent literature by Nakada et. al. (Chem. Pharm. Bull., 2019, 67, 173-185; previously cited on PTO-892; herein after referred to as “Nakada”).
Claims 7-8 have been cancelled, rendering their rejection moot. As such, the rejection of claims 7-8 under 35 U.S.C. 103 as being unpatentable over Masuda, Talele, and Nakada is withdrawn.
Claims 10 and 13-15 were rejected under 35 U.S.C. 103 as being unpatentable over US 2015/0297748 A1 (previously cited on PTO-892; herein after referred to as "Masuda"), Talele (J. Med. Chem., 2016, 59, 8712-8756; previously cited on PTO-892; herein after referred to as “Talele”), and Nakada et. al. (Chem. Pharm. Bull., 2019, 67, 173-185; previously cited on PTO-892; herein after referred to as “Nakada”), as applied to claims 1-5 and 7-9, and in further view of non-patent literature by Abdollahpour-Alitappeh et. al. (Iran. Biomed. J., 2017, 21(4), 270-274; previously cited on PTO-892; herein after referred to as “Alitappeh”).
Claims 10 and 13-15 have been cancelled, rendering their rejection moot. As such, the rejection of claims 10 and 13-15 under 35 U.S.C. 103 as being unpatentable over Masuda, Talele, Nakada, and Alitappeh is withdrawn.
Double Patenting - Withdrawn
Claims 13-15 were rejected on the grounds of nonstatutory double patenting as being unpatentable over claims 12 and 19-26 of U.S. Patent No. 12,377,163 (hereafter, "the '163 Patent") in view of Masuda, Talele, Nakada, and Alitappeh.
Claims 13-15 were rejected on the grounds of nonstatutory double patenting as being unpatentable over claims 1 and 10-13 of co-pending Application No. 17/914,087 in view of Masuda, Talele, Nakada, and Alitappeh.
Claims 13-15 were rejected on the grounds of nonstatutory double patenting as being unpatentable over claims 1-3, 8-9, 14, 16, 21-28, and 43 of copending Application No. 17/280,129 in view of Masuda, Talele, Nakada, and Alitappeh.
Claims 13-15 were rejected on the grounds of nonstatutory double patenting as being unpatentable over claims 1, 11-12, 14, 19-21, and 23 of co-pending Application No. 17/782,980 in view of Masuda, Talele, Nakada, and Alitappeh.
Claims 13-15 were rejected on the grounds of nonstatutory double patenting as being unpatentable over claims 1, 8, 10, 12-14, 18-20, and 22 of co-pending Application No. 17/785,373 in view of Masuda, Talele, Nakada, and Alitappeh.
Claims 13-15 were rejected on the grounds of nonstatutory double patenting as being unpatentable over claims 1, 10, 12-14, 16, 18-19, and 29 of copending Application No. 17/793,005 in view of Masuda, Talele, Nakada, and Alitappeh.
Claims 13-15 were rejected on the grounds of nonstatutory double patenting as being unpatentable over claims 1, 6-11, 13-16, and 18 of co-pending Application No. 17/914,209 in view of Masuda, Talele, Nakada, and Alitappeh.
Claims 13-15 were rejected on the grounds of nonstatutory double patenting as being unpatentable over claims 1-2, 12, and 19 of co-pending Application No. 18/029,075 in view of Masuda, Talele, Nakada, and Alitappeh.
Claims 13-15 were rejected on the grounds of nonstatutory double patenting as being unpatentable over claims 3 and 13-20 of co-pending Application No. 18/288,172 in view of Masuda, Talele, Nakada, and Alitappeh.
Claims 13-15 were rejected on the grounds of nonstatutory double patenting as being unpatentable over claim 1 of co-pending Application No. 18/580,602 in view of Masuda, Talele, Nakada, and Alitappeh.
Claims 13-15 were rejected on the grounds of nonstatutory double patenting as being unpatentable over claims 1 and 11-16 of co-pending Application No. 18/722,582 in view of Masuda, Talele, Nakada, and Alitappeh.
With regard to the above-listed claim rejections under nonstatutory double patenting, it is noted that claims 13-15 have been cancelled, rendering their rejections moot. As such, the above-listed nonstatutory double patenting rejections are withdrawn.
Claim Objections - New as Necessitated by Amendment
Claim 22 is objected to because of the following informalities: line 3 of the claim currently reads "using a packing material selected from the group consisting of CAPTO. Appropriate correction is required.
Claim Rejections - 35 USC § 112 - New as Necessitated by Amendment
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 21-22 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claims 21-22 contains the trademark/trade name “POROS™ XS” and/or “CAPTO™ S Impact”. Where a trademark or trade name is used in a claim as a limitation to identify or describe a particular material or product, the claim does not comply with the requirements of 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph. See Ex parte Simpson, 218 USPQ 1020 (Bd. App. 1982). The claim scope is uncertain since the trademark or trade name cannot be used properly to identify any particular material or product. A trademark or trade name is used to identify a source of goods, and not the goods themselves. Thus, a trademark or trade name does not identify or describe the goods associated with the trademark or trade name. In the present case, the trademark/trade name is used to identify/describe packing material for cation exchange chromatography and, accordingly, the identification/description is indefinite.
Claim Rejections - 35 USC § 103 - Maintained, Updated
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 (i.e., changing from AIA to pre-AIA ) 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 text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 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.
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.
It is noted that the crux of the rejections as updated below remain the same as presented in the previous Office Action (12/23/2025). The organization of the previously cited references have been updated to address the claims as instantly amended, but the rejections rely on the same teachings previously cited. As such, the rejections as updated below do not constitute a new grounds of rejection.
Claims 1-5, 9, and 11 stand as rejected, and new claims 16-20 and 23-24 are newly rejected, under 35 U.S.C. 103 as being unpatentable over US 2015/0297748 A1 (previously cited on PTO-892; herein after referred to as "Masuda"), CN 112125915 A (previously cited on PTO-892; original document published Dec. 2020; using US equivalent US 2022/0411436 A1 for translation; herein after referred to as "Zhu") and Talele (J. Med. Chem., 2016, 59, 8712-8756; previously cited on PTO-892; herein after referred to as “Talele”), and non-patent literature by Lou et. al. (Poster, “Bioconjugation Chemistries for ADC Preparation”, World ADC Summit, Oct. 2014; previously cited on PTO-892; herein after referred to as “Lou”).
With regard to claim 1, Masuda teaches an ADC wherein an antitumor compound represented by Formula 2, shown below, conjugated to an antibody via a linker having a structure represented by -L1-L2-LP-NH-(CH2)n1-La-Lb-Lc-; Formula 2 of Masuda corresponds to exatecan, the drug (D) of the instant application.
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Masuda further discloses various possible linker configurations for the ADCs of the invention (see Pages 9-11, for example). In particular, it is noted that Masuda discloses a drug-linker having a formula corresponding to the following (see Page 9, Column 1):
(maleimid-N-yl)-CH2CH2CH2CH2CH2-C(=O)-GGFGNH-CH2-O-CH2-C(=O)-(NH-DX).
It is specifically noted that NH-DX corresponds to the compound of Formula II connected to the linker via the -NH2 group. When the drug-linker above is reacted with an antibody, the resulting conjugate has a structure as shown below (Page 130), wherein M30-H1-L4P is an anti-B7-H3 antibody:
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Thus, Masuda teaches an antibody-drug conjugate wherein, corresponding to the instantly claimed ADC structure, W is C5 alkyl, L2 is a chemical bond, L3 is a four amino acid residue of Gly-Gly-Phe-Gly, Pc is an anti-B7-H3 antibody, and R1, R2, R5, R6, and R7 are all hydrogen. It is further noted that Masuda discloses methods for preparing ADCs of the invention. The production method of Masuda generally comprises reacting a drug-linker of the invention (e.g., the drug-linker provided above) with an antibody having a sulfahydryl group (Paragraphs 0322-0323). More specifically, an antibody having a sulfhydryl group can be obtained by a method well known in the art, including, but not limited to, the following: Traut's reagent is reacted with the amino group of the antibody; N-succinimidyl S-acetylthioalkanoates are reacted with the amino group of the antibody followed by reaction with hydroxylamine; after reacting with N-succinimidyl 3-(pyridyldithio)propionate, the antibody is reacted with a reducing agent; the antibody is reacted with a reducing agent such as dithiothreitol, 2-mercaptoethanol, and tris(2-carboxyethyl)phosphine hydrochloride (TCEP) to reduce the disulfide bond in a hinge part in the antibody to form a sulfhydryl group (Paragraph 0324; emphasis added). Using 0.3 to 3 molar equivalents of TCEP as a reducing agent per disulfide in hinge part in the antibody and reacting with the antibody in a buffer solution containing a chelating agent, the antibody with partially or completely reduced disulfide in hinge part in the antibody can be obtained; examples of the chelating agent include ethylenediamine tetraacetic acid (EDTA) and diethylenetriamine pentaacetic acid (DTPA) and examples of the buffer solution which may be used include a solution of sodium phosphate, sodium borate, or sodium acetate (Paragraph 0325). As a specific example, by reacting antibody with TCEP at 4 °C to 37 °C for 1 to 4 hours, an antibody having partially or completely reduced sulfhydryl group can be obtained (Id.). In an exemplary embodiment wherein the M30-H1-L4P ADC presented above was produced, it is noted that for the reduction of the antibody, the M30-Hl-L4P antibody was prepared to have an antibody concentration of 10 mg/mL by replacing the medium with PBS6.0/EDTA which was placed in a 1.5 mL polypropylene tube and charged with an aqueous solution of 10 mM (0.025 mL; 3.0 equivalents per antibody molecule) and an aqueous solution of 1 M dipotassium hydrogen phosphate (0.0625 mL) and after confirming that the solution had pH of 7.4 ± 0.1, the disulfide bond at hinge part in the antibody was reduced by incubating at 37 °C for 1 hour (Paragraph 0829). Thus, Masuda teaches a method of producing an antibody-drug conjugate wherein, corresponding to the general ADC formula (Pc-La-Y-D) of instant claim 1, wherein W is C5 alkyl, L2 is a chemical bond, L3 is a four amino acid residue of Gly-Gly-Phe-Gly, Pc is an antibody, and R1, R2, R5, R6, and R7 are all hydrogen, wherein the method comprises: (i) reacting an antibody with a reducing agent (e.g., TCEP) at a reaction temperature from 4 °C to 37 °C and (ii) subsequently reacting the reduced antibody with a drug linker corresponding to instant formula (La-Y-D) wherein W is C5 alkyl, L2 is a chemical bond, L3 is a four amino acid residue of Gly-Gly-Phe-Gly, R1, R2, R5, R6, and R7 are all hydrogen, m=0, and n is an integer or decimal between 3 and 8. However, it is noted that the above production method and subsequently antibody-drug conjugate of Masuda differs from the instantly elected method/antibody-drug conjugates wherein Masuda discloses groups corresponding to instant R1 and R2 that are both hydrogen, whereas the instant application requires, as pertains to the instant species election, a C3 cycloalkyl group at R1, and Masuda also does not disclose using an antibody that is the anti-HER2 antibody trastuzumab. These deficiencies are remedied by Zhu in view of Talele.
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Zhu provides the drug-linker compound represented by the general formula (L-X-D2) or its tautomer, mesomer, racemate, enantiomer, diastereomer or a mixture thereof, or a pharmaceutically acceptable salt or solvate thereof, which may include the structures shown below (Page 13), wherein the drug-linker may be reacted with an antibody to yield an antibody-drug conjugate (ADC) of general formula (Ab-L-X-Dr), which may have structures also shown below (Page 18).
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It is noted that the above structures read on general formula (Pc-La-Y-D) of instant claim 1 wherein W is C5 alkyl, L2 is a chemical bond, L3 is a four amino acid residue of Gly-Gly-Phe-Gly, Pc is an antibody, R1 is C3 cycloalkyl, R2, R5, R6, and R7 are all hydrogen, and m=0.
Zhu teaches an exemplary embodiment that also uses anti-HER2 antibody trastuzumab (see Example 35, Page 68). Zhu further teaches a generic coupling method wherein antibody molecules with a monomer rate greater than 95% after preliminary purification were dispersed into phosphate buffered saline containing EDTA using an ultrafiltration centrifuge tube at a concentration of 10 mg/mL after which: (i) 10 times the moles of TCEP (reducing agent) were added to the antibody and reacted at room temperature for 2 h; (ii) an ultrafiltration centrifuge tube was used to change the solution to pH 6.5 phosphate buffer, then DHAA was added at 10 times the molar number of the antibody and reacted at room temperature for 2 h; (iii) a payload of 15 times the molar number of the antibody was added, and the reaction was carried out at room temperature for 4 h; and (iv) after the reaction, an ultrafiltration centrifuge tube with a molecular weight cut-off of 30 KDa was used to change the medium to PBS, and remove the uncoupled payload (Paragraph 0349).
Talele teaches an increasing use of the cyclopropyl ring in drug development to transition drug candidates from the preclinical to clinical stage; important features of the cyclopropane ring are, the (1) coplanarity of the three carbon atoms, (2) relatively shorter (1.51 Å) C−C bonds, (3) enhanced π-character of C−C bonds, and (4) C−H bonds are shorter and stronger than those in alkanes (Abstract). The cyclopropyl ring addresses multiple roadblocks that can occur during drug discovery such as (a) enhancing potency, (b) reducing off-target effects, (c) increasing metabolic stability, (d) increasing brain permeability, (e) decreasing plasma clearance, (f) contributing to an entropically more favorable binding to the receptor, (g) conformational restriction of peptides/peptidomimetics to prevent proteolytic hydrolysis, and (h) altering drug pKa to reduce its P-glycoprotein (P-gp) efflux ratio (Id.). A centrally located cyclopropane ring can impose significant steric constraints on the conformation of an entire molecule whereas the terminally located cyclopropane ring is expected to impose only limited steric rigidity; a centrally located chiral cyclopropane ring, through its considerable rigidity, helps to position pendant pharmacophore groups in complementary binding pockets of the target protein and the molecular configuration provided by the centrally located cyclopropane ring can enhance non-coplanarity, target specificity, mitigate off target activity, reduce crystal packing, and increase aqueous solubility (Pages 8743-8744). Talele highlights the role played by the versatile cyclopropyl ring as exemplified by FDA approved drugs and preclinical/clinical candidates (see Table 1) and it is suggested that scientists involved in drug discovery may be motivated, in light of Talele’s review, to exploit the cyclopropane ring either as a substituent, as a chiral bridge, and as a spiro or fused ring in solving multiple challenges that occur during the course of drug discovery program and including target specificity, therapeutic potency, ligand efficiency, ligand lipophilic efficiency, aqueous solubility, pKa, log P, tuning of phase I oxidative/hydrolytic drug metabolism, sterically limiting the phase II glucuronide conjugation, cell permeability, oral bioavailability, plasma clearance, biological half-life, chemical stability, liver microsomal stability, eliminating isomerizable noncyclic C-C bond through cyclopropanation, removal of Michael acceptor through cyclopropanation, and in the case of CNS active drugs, tuning of brain penetration, P-gp efflux ratio, and CNS receptor occupancy (Pages 8744-8748; Table 1).
However, it is noted that none of Masuda, Zhu, or Talele explicitly disclose methods of preparing ADCs comprising (a) reacting trastuzumab with a reducing agent at a reaction temperature of about 1 oC to 36 oC wherein said reaction is performed in a histidine salt buffer and (b) reacting the product of step (a) with a compound of the formula shown below:
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This deficiency is remedied by Lou.
Lou discloses that in a typical preparation of cysteine mediated ADC, the interchain disulfide bonds are partially reduced with a reducing agent such as tris(carboxyethyl) phosphine (TCEP) and then the resulting free thiols are conjugated to a maleimide-containing linker-payload; the authors evaluated several parameters with respect to the conjugation of IgG1 antibodies with payload-linkers including: (i) TCEP stoichiometry, (ii) linker-payload stoichiometry, (iii) reaction pH, (iv) buffer concentration/ionic strength, (v) antibody concentration, and (vi) temperature (First Column, Conventional Cysteine Mediated Conjugation). It is noted that the buffer used throughout the above-listed experiments of Lou is a histidine buffer (see experimental conditions listed in Columns 2-3), but Lou also conducted experiments testing different buffers (Table 6). Figure 4/Table1/Chart 1 all indicate that an increased TCEP stoichiometry ratio corresponds to higher DAR values for IgG1 ADCs; Table 3/Chart 5 indicate that a pH of about 6-7 is optimal under the given experimental conditions, but that at a pH between about 5-6 conjugation still occurs with an average DAR of approximately 2.5-3.5 compared to an average DAR of approximately 3.5-4 for pH of about 6-7; Table 6 indicates that histidine and HEPES are the best buffer systems for conjugation; and Table 7 indicates that lower reduction temperatures are better for reducing the amount of unmodified IgG1 antibody, but higher temperatures are also sufficient for conjugation with similar DAR and only slightly increased percentages of unmodified antibody. It is further noted that, as evidenced by the references, the reaction components for antibody reduction in ADC production (i.e., buffer identity/concentration, reducing agent identity/concentration, reaction temperature, and/or reaction pH, and reaction time) are recognized as reaction variables which achieves a recognized result and as set forth in MPEP 2144.05: “A particular parameter must first be recognized as a result-effective variable, i.e., a variable which achieves a recognized result, before the determination of the optimum or workable ranges of said variable might be characterized as routine experimentation.” In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). It is a common objective in the art to optimize result effective variables, so as achieve optimal effect and maximal benefit. See In re Boesch, 617 F.2d 272, 276, 205 USPQ 215, 219 (CCPA 1980) (“[D]iscovery of an optimum value of a result effective variable in a known process is ordinarily within the skill of the art.” (citations omitted)). Therefore, any optimization of reaction variable would be seen as routine optimization.
Thus, it would have been obvious to one of ordinary skill in the art to utilize the ADC production method of Masuda corresponding to the general ADC formula (Pc-La-Y-D) of instant claim 1, wherein W is C5 alkyl, L2 is a chemical bond, L3 is a four amino acid residue of Gly-Gly-Phe-Gly, Pc is an antibody, R1, R2, R5, R6, and R7 are all hydrogen, and m=0 (full exemplary structure shown below), wherein the method comprises: (i) reacting an antibody (e.g., M30-H1-L4P) with a reducing agent (e.g., TCEP) at a reaction temperature from 4 °C to 37 °C and (ii) subsequently reacting the reduced antibody with a drug linker corresponding to instant formula (La-Y-D) wherein W is C5 alkyl, L2 is a chemical bond, L3 is a four amino acid residue of Gly-Gly-Phe-Gly, R1, R2, R5, R6, and R7 are all hydrogen, m=0, and n is an integer or decimal between 3 and 8 wherein the ADCs of Masuda could be modified such that a cyclopropane group is added to the deliverable drug portion of an antibody-drug conjugate at the location corresponding to instant R1, as suggested by Zhu, with the motivation of developing a drug with improved/beneficial therapeutic properties, as suggested by Talele, wherein one having ordinary skill in the art would recognize that such a modification would be beneficial to an ADC when said modification is either (i) to the drug itself or (ii) proximal to the drug/part of the cleaved drug product wherein the addition of a cyclopropane group would be expected to enhance potency, reduce off-target effects, increase metabolic stability, increase brain permeability, decrease plasma clearance, contribute to an entropically more favorable binding to the receptor, conformationally restrict peptides/peptidomimetics to prevent proteolytic hydrolysis, and/or alter drug pKa to reduce its P-gp efflux ratio. Additionally, the ADC of Masuda could further be modified such that instead of the exemplary M30-H1-LP4 antibody, anti-HER2 antibody trastuzumab could be used instead, as suggested by Zhu, wherein one of ordinary skill in the art would have been motivated to select trastuzumab with the motivation of targeting HER2 expressing cancers. Such modifications would have been obvious to one of ordinary skill in the art because combining prior art elements according to known methods would be expected to yield predictable results; the above-described modifications to the method/ADC of Masuda would yield an ADC of the structure shown below corresponding to the general ADC formula (Pc-La-Y-D) of instant claim 1, wherein W is C5 alkyl, L2 is a chemical bond, L3 is a four amino acid residue of Gly-Gly-Phe-Gly, Pc is anti-HER2 antibody trastuzumab, R1 is a C3 cycloalkyl, R2, R5, R6, and R7 are all hydrogen, m=0, and n is an integer or decimal between 3 and 8 further wherein said ADC would be expected to be efficacious for HER2 expressing cancers, and wherein the ADC would be expected to have improved therapeutic properties and subsequently
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enhanced efficacy attributed to the addition of the C3 cycloalkyl group.
Furthermore, one of ordinary skill in the art would recognize, based on the teachings of Lou, that the ADC production method, trastuzumab antibody, and drug-linker rendered obvious by the combination of Masuda, Zhu, and Talele could be further modified such that the antibody reduction step of the method is carried out at a temperature of 1 oC to 36 oC, as suggested by Masuda and Lou, and wherein the reduction step is performed in a histidine salt buffer, as suggested by Lou, because combining prior art elements according to known methods would be expected to yield predictable results. One having ordinary skill in the art would have been motivated to modify and optimize the antibody reduction reaction conditions such that the reduction step yields reduced antibodies capable of producing an ADC of a desired DAR; Lou specifically indicates that histidine buffers are preferential and reduction reactions in histidine buffers are successful and useful for ADC production, wherein the studies of Lou further suggest that reaction parameters (temperature, TCEP stoichiometry, buffer identity, temperature, etc.) are further optimizable.
Claims 6 and 12 stand as rejected under 35 U.S.C. 103 as being unpatentable over US 2015/0297748 A1 (previously cited on PTO-892; herein after referred to as "Masuda"), CN 112125915 A (previously cited on PTO-892; original document published Dec. 2020; using US equivalent US 2022/0411436 A1 for translation; herein after referred to as "Zhu") and Talele (J. Med. Chem., 2016, 59, 8712-8756; previously cited on PTO-892; herein after referred to as “Talele”), and non-patent literature by Lou et. al. (Poster, “Bioconjugation Chemistries for ADC Preparation”, World ADC Summit, Oct. 2014; previously cited on PTO-892; herein after referred to as “Lou”), as applied to claims 1-5, 7-9, 11, and 16-20 above, and in further view of US 2019/0367556 A1 (previously cited on PTO-892; herein after referred to as “Nadkarni”).
Claim 1 is rendered obvious by the combination of Masuda, Zhu, Talele, and Lou. Masuda does suggest that the produced antibody-drug conjugate can be subjected to, after concentration, buffer exchange, purification, and measurement of antibody concentration and average number of conjugated drug molecules per antibody molecule according to common procedures (Paragraph 0328; emphasis added). The purification step explicitly disclosed by Masuda, however, relies on column chromatography using a NAP-25 column, which is a size-exclusion column (Paragraph 0333). However, none of the cited references explicitly disclose a purification step using cation column chromatography and/or affinity column chromatography. This deficiency is remedied by Nadkarni.
Nadkarni teaches methods of removing high molecular weight species, in particular aggregates, from antibody drug conjugate preparations, by contacting preparations of the antibody drug conjugate reaction mixture with a hydroxyapatite resin and selectively eluting the ADC from the resin using a gradient comprising sodium phosphate (Abstract). The inventors disclose that a phosphate gradient can be used in a hydroxyapatite chromatography method for the purification of ADC monomers from aggregate impurities by selectively removing aggregates, as well as low molecular weight impurities like organic solvents and unconjugated ("free") payload (Paragraph 0018). Functional groups consist of pairs of positively charged calcium ions (C-sites) and clusters of negatively charged phosphate groups (P-sites); the interactions between hydroxyapatite and proteins are complex and multi-mode; in one method of interaction, however, positively charged amino groups on proteins associate with the negatively charged P-sites (i.e., cation-exchange) and protein carboxyl groups interact by coordination complexation to C-sites (Paragraph 0009).
Thus, it would have been obvious to one of ordinary skill in the art to utilize the ADC production method of instant claim 1 rendered obvious by Masuda, Zhu, Talele, and Lou wherein said method could be modified to further comprise a purification step, as suggested by Masuda, wherein said purification step can comprise contacting the ADC preparation with a cation exchange column, such as that suggested by Nadkarni, because combining prior art elements according to known methods would be expected to yield predictable results. One having ordinary skill in the art would have been motivated to modify the production method rendered obvious by Masuda, Zhu, Talele, and Lou such that a purification step comprises cation column chromatography with the motivation of removing aggregates and impurities in order to isolate as much ADC as possible.
Claims 1-5, 9, and 11 stand as rejected, and new claims 16-20 and 23-24 are newly rejected, under 35 U.S.C. 103 as being unpatentable over US 2015/0297748 A1 (previously cited on PTO-892; herein after referred to as "Masuda") in view of non-patent literature by Talele (J. Med. Chem., 2016, 59, 8712-8756; previously cited on PTO-892; herein after referred to as “Talele”), non-patent literature by Nakada et. al. (Chem. Pharm. Bull., 2019, 67, 173-185; previously cited on PTO-892; herein after referred to as “Nakada”), and non-patent literature by Lou et. al. (Poster, “Bioconjugation Chemistries for ADC Preparation”, World ADC Summit, Oct. 2014; previously cited on PTO-892; herein after referred to as “Lou”).
Masuda teaches an ADC wherein an antitumor compound represented by Formula 2, shown below, conjugated to an antibody via a linker having a structure represented by -L1-L2-LP-NH-(CH2)n1-La-Lb-Lc-; Formula 2 of Masuda corresponds to exatecan, the drug (D) of the instant application.
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Masuda further discloses various possible linker configurations for the ADCs of the invention (see Pages 9-11, for example). In particular, it is noted that Masuda discloses a drug-linker having a formula corresponding to the following (see Page 9, Column 1):
(maleimid-N-yl)-CH2CH2CH2CH2CH2-C(=O)-GGFGNH-CH2-O-CH2-C(=O)-(NH-DX).
It is specifically noted that NH-DX corresponds to the compound of Formula II connected to the linker via the -NH2 group. When the drug-linker above is reacted with an antibody, the resulting conjugate has a structure as shown below (Page 130), wherein M30-H1-L4P is an anti-B7-H3 antibody:
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Thus, Masuda teaches an antibody-drug conjugate wherein, corresponding to the instantly claimed ADC structure, W is C5 alkyl, L2 is a chemical bond, L3 is a four amino acid residue of Gly-Gly-Phe-Gly, Pc is an anti-B7-H3 antibody, and R1, R2, R5, R6, and R7 are all hydrogen. It is further noted that Masuda discloses methods for preparing ADCs of the invention. The production method of Masuda generally comprises reacting a drug-linker of the invention (e.g., the drug-linker provided above) with an antibody having a sulfahydryl group (Paragraphs 0322-0323). More specifically, an antibody having a sulfhydryl group can be obtained by a method well known in the art, including, but not limited to, the following: Traut's reagent is reacted with the amino group of the antibody; N-succinimidyl S-acetylthioalkanoates are reacted with the amino group of the antibody followed by reaction with hydroxylamine; after reacting with N-succinimidyl 3-(pyridyldithio)propionate, the antibody is reacted with a reducing agent; the antibody is reacted with a reducing agent such as dithiothreitol, 2-mercaptoethanol,
and tris(2-carboxyethyl)phosphine hydrochloride (TCEP) to reduce the disulfide bond in a hinge part in the antibody to form a sulfhydryl group (Paragraph 0324; emphasis added). Using 0.3 to 3 molar equivalents of TCEP as a reducing agent per disulfide in hinge part in the antibody and reacting with the antibody in a buffer solution containing a chelating agent, the antibody with partially or completely reduced disulfide in hinge part in the antibody can be obtained; examples of the chelating agent include ethylenediamine tetraacetic acid (EDTA) and diethylenetriamine pentaacetic acid (DTPA) and examples of the buffer solution which may be used include a solution of sodium phosphate, sodium borate, or sodium acetate (Paragraph 0325). As a specific example, by reacting antibody with TCEP at 4 °C to 37 °C for 1 to 4 hours, an antibody having partially or completely reduced sulfhydryl group can be obtained (Id.). In an exemplary embodiment wherein the M30-H1-L4P ADC presented above was produced, it is noted that for the reduction of the antibody, the M30-Hl-L4P antibody was prepared to have an antibody concentration of 10 mg/mL by replacing the medium with PBS6.0/EDTA which was placed in a 1.5 mL polypropylene tube and charged with an aqueous solution of 10 mM (0.025 mL; 3.0 equivalents per antibody molecule) and an aqueous solution of 1 M dipotassium hydrogen phosphate (0.0625 mL) and after confirming that the solution had pH of 7.4 ± 0.1, the disulfide bond at hinge part in the antibody was reduced by incubating at 37 °C for 1 hour (Paragraph 0829). Thus, Masuda teaches a method of producing an antibody-drug conjugate wherein, corresponding to the general ADC formula (Pc-La-Y-D) of instant claim 1, wherein W is C5 alkyl, L2 is a chemical bond, L3 is a four amino acid residue of Gly-Gly-Phe-Gly, Pc is an antibody, and R1, R2, R5, R6, and R7 are all hydrogen, wherein the method comprises: (i) reacting an antibody with a reducing agent (e.g., TCEP) at a reaction temperature from 4 °C to 37 °C and (ii) subsequently reacting the reduced antibody with a drug linker corresponding to instant formula (La-Y-D) wherein W is C5 alkyl, L2 is a chemical bond, L3 is a four amino acid residue of Gly-Gly-Phe-Gly, R1, R2, R5, R6, and R7 are all hydrogen, m=0, and n is an integer or decimal between 3 and 8. However, it is noted that the above production method and subsequently antibody-drug conjugate of Masuda differs from the instantly elected method/antibody-drug conjugates wherein Masuda discloses groups corresponding to instant R1 and R2 that are both hydrogen, whereas the instant application requires, as pertains to the instant species election, a C3 cycloalkyl group at R1, and Masuda also does not disclose using an antibody that is the anti-HER2 antibody trastuzumab. These deficiencies are remedied by Talele and Nakada.
Talele teaches an increasing use of the cyclopropyl ring in drug development to transition drug candidates from the preclinical to clinical stage; important features of the cyclopropane ring are, the (1) coplanarity of the three carbon atoms, (2) relatively shorter (1.51 Å) C−C bonds, (3) enhanced π-character of C−C bonds, and (4) C−H bonds are shorter and stronger than those in alkanes (Abstract). The cyclopropyl ring addresses multiple roadblocks that can occur during drug discovery such as (a) enhancing potency, (b) reducing off-target effects, (c) increasing metabolic stability, (d) increasing brain permeability, (e) decreasing plasma clearance, (f) contributing to an entropically more favorable binding to the receptor, (g) conformational restriction of peptides/peptidomimetics to prevent proteolytic hydrolysis, and (h) altering drug pKa to reduce its P-glycoprotein (P-gp) efflux ratio (Id.). A centrally located cyclopropane ring can impose significant steric constraints on the conformation of an entire molecule whereas the terminally located cyclopropane ring is expected to impose only limited steric rigidity; a centrally located chiral cyclopropane ring, through its considerable rigidity, helps to position pendant pharmacophore groups in complementary binding pockets of the target protein and the molecular configuration provided by the centrally located cyclopropane ring can enhance non-coplanarity, target specificity, mitigate off target activity, reduce crystal packing, and increase aqueous solubility (Pages 8743-8744). Talele highlights the role played by the versatile cyclopropyl ring as exemplified by FDA approved drugs and preclinical/clinical candidates (see Table 1) and it is suggested that scientists involved in drug discovery may be motivated, in light of Talele’s review, to exploit the cyclopropane ring either as a substituent, as a chiral bridge, and as a spiro or fused ring in solving multiple challenges that occur during the course of drug discovery program and including target specificity, therapeutic potency, ligand efficiency, ligand lipophilic efficiency, aqueous solubility, pKa, log P, tuning of phase I oxidative/hydrolytic drug metabolism, sterically limiting the phase II glucuronide conjugation, cell permeability, oral bioavailability, plasma clearance, biological half-life, chemical stability, liver microsomal stability, eliminating isomerizable noncyclic C-C bond through cyclopropanation, removal of Michael acceptor through cyclopropanation, and in the case of CNS active drugs, tuning of brain penetration, P-gp efflux ratio, and CNS receptor occupancy (Pages 8744-8748; Table 1).
Nakada teaches that [fam-] Trastuzumab deruxtecan (DS-8201a) is a next-generation ADC that satisfies efficacy and reduced toxicity requirements based on currently available evidence, and DS-8201a has several innovative features: a highly potent novel payload with a high drug-to-antibody ratio, good homogeneity, a tumor-selective cleavable linker, stable linker-payload in circulation, and a short systemic half-life cytotoxic agent in vivo; and the released cytotoxic payload could exert a bystander effect (Abstract). With respect to its preclinical profiles, DS-8201a could provide a valuable therapy with a great potential against HER2-
expressing cancers in clinical settings; in a phase I trial, DS-8201a showed acceptable safety profiles with potential therapeutic efficacy, with the wide therapeutic index (Abstract). The ADC structure of DS-8201a is shown in Figure 8 and is reproduced below:
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Nakada further teaches that, for cysteine conjugation methods, the interchain disulfide bridges of IgG1 antibodies often need to be selectively reduced prior to conjugation with linker, and the low abundance of only eight Cys residues on the interchain bridge allows easier control of the DAR (Page 177, Column 2, Conjugation Chemistry). Since the reducing agent cannot reach intrachain disulfide bridges inside the molecule, these cannot be reduced; it was suggested that neither disruption of the interchain bridge nor the coupling of eight linkers affected
clearance and stability of the antibody itself since there was no significant difference in the pharmacokinetics between unconjugated parental mAb (not reduced) and the modified mAb with Cys conjugation (interchain disulfide bonds fully reduced) (Id.). The antibody of DS-8201a is a humanized IgG1 monoclonal antibody produced with reference to the amino acid sequence of trastuzumab; thus, DS-8201a binds to HER2 as well as trastuzumab (Page 178, Column 1, First Full Paragraph). The cytotoxic payload on DS-8201a is a camptothecin (CPT) analog known as a topoisomerase I inhibitor; CPTs were able to bind and stabilize the triple-complex with DNA topoisomerase I (Topo 1) and DNA, induce DNA damage and lead to apoptosis of cells (Id.). Exatecan methanesulfonate (DX-8951f) is a water-soluble CPT that exhibits more potent topo I inhibitory activity and antitumor activity than other CPT analogs, and exatecan is effective
against P-glycoprotein (P-gp)-mediated multi-drug resistant cells (Page 178, Column 1, First Partial Paragraph). Various linkers and exatecan derivatives, which are highly efficient CPT analogs, have been investigated (Table 2), and the topoisomerase I inhibitory potency of the novel exatecan derivative (DXd, 19) was 10-fold higher than SN-38; DXd is therefore expected to have sufficient efficacy when used as a payload for ADCs (Id.). The linker between the antibody and payload is an enzymatically cleavable peptide (GGFG)-based linker, and a self-immolative amino methylene spacer, which reduced hydrophobicity compared with the conventional p-amino benzyl (pAB) spacer and provided stability in systemic circulation; the mechanism of drug release is shown in Fig. 11 wherein first the internalized ADC is selectively cleaved to a temporary hydrolysate composed of DXd by lysosomal proteases in tumor cells and subsequently an amino-methylene (AM), which is designed as a self-immolative spacer, is rapidly hydrolyzed to ammonia and formaldehyde wherein intracellular release of DXd occurs to trigger cell death (Page 178, Column 2, Last Full Paragraph). Moreover, it is noted that DXd was designed to have good cell membrane permeability so as to show a bystander effect of the ADC (Id.). HER2 is a member of the epidermal growth factor receptor (EGFR) family of transmembrane receptors and overexpressed in a broad number of cancer types, such as breast, colorectal, gastric, lung, and ovarian cancers; The efficacy of DS-8201a was compared with T-DM1 (ADC wherein emtansine is conjugated to trastuzumab via lysine) and a lower-DAR HER2 ADC (DAR 3.4, the same the DS-8201a linker-payload) in mice xenograft models with different levels of HER2 expression (Fig. 12) wherein: (i) T-DM1 showed efficacy only in KPL-4, a breast cancer cell line with high HER2 expression while DS-8201a was effective in the cell line Capan-1, a pancreatic cell line with low HER2 expression, in addition to efficacy in KPL-4 and JIMT-1 (a T-DM1 refractory HER2-positive breast cancer cell line); (ii) neither ADCs were
effective in the GCIY cell line, which is a gastric cancer cell line negative for HER2 expression; (iii) an ADC of DAR 3.4 indicated antitumor activity against all levels of HER2 expression, but the degree was dependent on the expression of HER2, and the activity of an ADC of DAR 3.4 in low-expressing HER2 Capan-1 cells was weaker than that of DS-8201a with a DAR of 8 (Pages 179-180). These results showed that the high DAR of DS-8201a can deliver more drug into tumor cells compared with T-DM1 and a DAR of 3.4, and DS-8201a showed preliminary evidence of activity in low-expressing HER2 tumors (Id.). DS-8201a differs from T-DM1 in several ways: 1) different mechanism of action, 2) antitumor efficacy in HER2 low expressing tumors owing to high DAR and stability, and 3) antitumor activity in heterogenic tumors owing to the bystander effect (Page 183, Column 2, First Full Paragraph).
However, it is noted that none of Masuda, Zhu, or Talele explicitly disclose methods of preparing ADCs comprising (a) reacting trastuzumab with a reducing agent at a reaction temperature of about 1 oC to 36 oC wherein said reaction is performed in a histidine salt buffer and (b) reacting the product of step (a) with a compound of the formula shown below:
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This deficiency is remedied by Lou.
Lou discloses that in a typical preparation of cysteine mediated ADC, the interchain disulfide bonds are partially reduced with a reducing agent such as tris(carboxyethyl) phosphine (TCEP) and then the resulting free thiols are conjugated to a maleimide-containing linker-payload; the authors evaluated several parameters with respect to the conjugation of IgG1 antibodies with payload-linkers including: (i) TCEP stoichiometry, (ii) linker-payload stoichiometry, (iii) reaction pH, (iv) buffer concentration/ionic strength, (v) antibody concentration, and (vi) temperature (First Column, Conventional Cysteine Mediated Conjugation). It is noted that the buffer used throughout the above-listed experiments of Lou is a histidine buffer (see experimental conditions listed in Columns 2-3), but Lou also conducted experiments testing different buffers (Table 6). Figure 4/Table1/Chart 1 all indicate that an increased TCEP stoichiometry ratio corresponds to higher DAR values for IgG1 ADCs; Table 3/Chart 5 indicate that a pH of about 6-7 is optimal under the given experimental conditions, but that at a pH between about 5-6 conjugation still occurs with an average DAR of approximately 2.5-3.5 compared to an average DAR of approximately 3.5-4 for pH of about 6-7; Table 6 indicates that histidine and HEPES are the best buffer systems for conjugation; and Table 7 indicates that lower reduction temperatures are better for reducing the amount of unmodified IgG1 antibody, but higher temperatures are also sufficient for conjugation with similar DAR and only slightly increased percentages of unmodified antibody. It is further noted that, as evidenced by the references, the reaction components for antibody reduction in ADC production (i.e., buffer identity/concentration, reducing agent identity/concentration, reaction temperature, and/or reaction pH, and reaction time) are recognized as reaction variables which achieves a recognized result and as set forth in MPEP 2144.05: “A particular parameter must first be recognized as a result-effective variable, i.e., a variable which achieves a recognized result, before the determination of the optimum or workable ranges of said variable might be characterized as routine experimentation.” In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). It is a common objective in the art to optimize result effective variables, so as achieve optimal effect and maximal benefit. See In re Boesch, 617 F.2d 272, 276, 205 USPQ 215, 219 (CCPA 1980) (“[D]iscovery of an optimum value of a result effective variable in a known process is ordinarily within the skill of the art.” (citations omitted)). Therefore, any optimization of reaction variable would be seen as routine optimization.
Thus, it would have been obvious to one of ordinary skill in the art to utilize the ADC production method of Masuda corresponding to the general ADC formula (Pc-La-Y-D) of instant claim 1, wherein W is C5 alkyl, L2 is a chemical bond, L3 is a four amino acid residue of Gly-Gly-Phe-Gly, Pc is an antibody, R1, R2, R5, R6, and R7 are all hydrogen, and m=0 (full exemplary structure shown below), wherein the method comprises: (i) reacting an antibody (e.g., M30-H1-L4P) with a reducing agent (e.g., TCEP) at a reaction temperature from 4 °C to 37 °C and (ii) subsequently reacting the reduced antibody with a drug linker corresponding to instant formula (La-Y-D) wherein W is C5 alkyl, L2 is a chemical bond, L3 is a four amino acid residue of Gly-Gly-Phe-Gly, R1, R2, R5, R6, and R7 are all hydrogen, m=0, and n is an integer or decimal between 3 and 8.
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Furthermore, one of ordinary skill in the art would recognize, based on the teachings of Lou, that the ADC production method, trastuzumab antibody, and drug-linker rendered obvious by the combination of Masuda, Talele, and Nakada could be further modified such that the antibody reduction step of the method is carried out at a temperature of 1 oC to 36 oC, as suggested by Masuda and Lou, and wherein the reduction step is performed in a histidine salt buffer, as suggested by Lou, because combining prior art elements according to known methods would be expected to yield predictable results. One having ordinary skill in the art would have been motivated to modify and optimize the antibody reduction reaction conditions such that the reduction step yields reduced antibodies capable of producing an ADC of a desired DAR; Lou specifically indicates that histidine buffers are preferential and reduction reactions in histidine buffers are successful and useful for ADC production, wherein the studies of Lou further suggest that reaction parameters (temperature, TCEP stoichiometry, buffer identity, temperature, etc.) are further optimizable.
Claim 6 and 12 stand as rejected under 35 U.S.C. 103 as being unpatentable over US 2015/0297748 A1 (previously cited on PTO-892; herein after referred to as "Masuda"), Talele (J. Med. Chem., 2016, 59, 8712-8756; previously cited on PTO-892; herein after referred to as “Talele”), non-patent literature by Nakada et. al. (Chem. Pharm. Bull., 2019, 67, 173-185; previously cited on PTO-892; herein after referred to as “Nakada”), and non-patent literature by Lou et. al. (Poster, “Bioconjugation Chemistries for ADC Preparation”, World ADC Summit, Oct. 2014; previously cited on PTO-892; herein after referred to as “Lou”), as applied to claims 1-5, 9, 11, 16-20, and 23-24, and in further view of US 2019/0367556 A1 (previously cited on PTO-892; herein after referred to as “Nadkarni”).
The method of claim 1 is rendered obvious by Masuda, Talele, Nakada, and Lou. Masuda does suggest that the produced antibody-drug conjugate can be subjected to, after concentration, buffer exchange, purification, and measurement of antibody concentration and average number of conjugated drug molecules per antibody molecule according to common procedures (Paragraph 0328). The purification step explicitly disclosed by Masuda, however, relies on column chromatography using a NAP-25 column, which is a size-exclusion column (Paragraph 0333). Thus, none of the cited references explicitly disclose an additional step of purifying the ADC with affinity or cation column chromatography. This deficiency is remedied by Nadkarni.
Nadkarni teaches methods of removing high molecular weight species, in particular aggregates, from antibody drug conjugate preparations, by contacting preparations of the antibody drug conjugate reaction mixture with a hydroxyapatite resin and selectively eluting the ADC from the resin using a gradient comprising sodium phosphate (Abstract). The inventors disclose that a phosphate gradient can be used in a hydroxyapatite chromatography method for the purification of ADC monomers from aggregate impurities by selectively removing aggregates, as well as low molecular weight impurities like organic solvents and unconjugated ("free") payload (Paragraph 0018). Functional groups consist of pairs of positively charged calcium ions (C-sites) and clusters of negatively charged phosphate groups (P-sites); the interactions between hydroxyapatite and proteins are complex and multi-mode; in one method of interaction, however, positively charged amino groups on proteins associate with the negatively charged P-sites (i.e., cation-exchange) and protein carboxyl groups interact by coordination complexation to C-sites (Paragraph 0009).
Masuda, Talele, Nakada, Lou, and Nadkarni are considered to be analogous to the present invention as they are in the same field of antibody-drug conjugates/compositions for optimized drug delivery and methods of preparation/purification therefor. Thus, it would have been obvious to one of ordinary skill in the art to utilize the ADC production method of instant claim 1 rendered obvious by Masuda, Talele, and Nakada wherein said method could be modified to further comprise a purification step, as suggested by Masuda, wherein said purification step can comprise contacting the ADC preparation with a cation exchange column, such as that suggested by Nadkarni, because combining prior art elements according to known methods would be expected to yield predictable results. One having ordinary skill in the art would have been motivated to modify the production method rendered obvious by Masuda, Talele, and Nakada such that a purification step comprises cation column chromatography with the motivation of removing aggregates and impurities in order to isolate as much ADC as possible.
Claim Rejections - 35 USC § 103 - New as Necessitated by Amendment
Claims 21-22 are rejected under 35 U.S.C. 103 as being unpatentable over US 2015/0297748 A1 (previously cited on PTO-892; herein after referred to as "Masuda"), CN 112125915 A (previously cited on PTO-892; original document published Dec. 2020; using US equivalent US 2022/0411436 A1 for translation; herein after referred to as "Zhu") and Talele (J. Med. Chem., 2016, 59, 8712-8756; previously cited on PTO-892; herein after referred to as “Talele”), and non-patent literature by Lou et. al. (Poster, “Bioconjugation Chemistries for ADC Preparation”, World ADC Summit, Oct. 2014; previously cited on PTO-892; herein after referred to as “Lou”), and US 2019/0367556 A1 (previously cited on PTO-892; herein after referred to as “Nadkarni”) as applied to claims 1-9, 11-12, and 16-20 above, and further in view of WO 2018/177369 A1 (machine translation of the description provided; herein after referred to as "Liu").
Claim 6 is rendered obvious by the combination of Masuda, Zhu, Talele, Lou, and Nadkarni. However, none of the cited references explicitly disclose using a cation exchange chromatography packing material selected from POROS™ XS and/or CAPTO™ S Impact. This deficiency is remedied by Liu.
Liu discloses a method for preparing an antibody drug conjugate wherein the invention relates to the preparation of antibody drug conjugates (ADCs) using an ion exchange column as a carrier (Technical Field, Page 1). While the focus of Liu is the preparation of ADCs on a cation exchange column, Liu also teaches cation exchange chromatography has been used for ADC separation and/or purification (Page 2, First Full Paragraph). Liu further teaches that antigen-binding proteins that may be used in methods of the invention include Herceptin (i.e., trastuzumab) (Page 5, Last Paragraph). Cation exchange resins useful in the method of the invention include Millpore Fractogel SO3; Millpore Eshmuno S; Millpore Eshmuno CPX; GE Capto S Impact; GE SP Sepharose Fast Flow; HiTrapTM Capto S ImpAct (Page 18, Last Paragraph; emphasis added). Example 8 demonstrates that after production, ADCs can be eluted from the cation exchange columns (see Pages 27-28). Thus, Liu established the use of cation exchange resins (i.e., packing materials) for both ADC preparation and separation/purification.
Thus, it would have been obvious to one of ordinary skill in the art to utilize the ADC production method of instant claim 6 rendered obvious by Masuda, Zhu, Talele, Lou, and Nadkarni wherein said method could be modified to comprise a purification step, as suggested by Masuda, wherein said purification step can comprise contacting the ADC preparation with a cation exchange column, such as that suggested by Nadkarni, wherein said cation exchange column may comprise CAPTO™ S Impact packing material, as suggested by Liu, because the simple substitution of one known element for another would be expected to yield predictable results. One having ordinary skill in the art would have recognized that the production method rendered obvious by Masuda, Zhu, Talele, Lou, and Nadkarni could utilize the cationic packing material CAPTO™ S Impact for practicing cation column chromatography in the purification step because said packing material is disclosed by Liu to be useful in both ADC production and separation/purification; thus using the cationic packing material CAPTO™ S Impact for practicing cation column chromatography would reasonably be expected to successfully purify trastuzumab ADCs.
Claims 21-22 are rejected under 35 U.S.C. 103 as being unpatentable over US 2015/0297748 A1 (previously cited on PTO-892; herein after referred to as "Masuda"), Talele (J. Med. Chem., 2016, 59, 8712-8756; previously cited on PTO-892; herein after referred to as “Talele”), non-patent literature by Nakada et. al. (Chem. Pharm. Bull., 2019, 67, 173-185; previously cited on PTO-892; herein after referred to as “Nakada”), and non-patent literature by Lou et. al. (Poster, “Bioconjugation Chemistries for ADC Preparation”, World ADC Summit, Oct. 2014; previously cited on PTO-892; herein after referred to as “Lou”), and US 2019/0367556 A1 (herein after referred to as “Nadkarni”), as applied to claims 1-9, 11-12, and 16-20 above, and further in view of WO 2018/177369 A1 (machine translation of the description provided; herein after referred to as "Liu").
Claim 6 is rendered obvious by the combination of Masuda, Talele, Nakada, Lou, and Nadkarni. However, none of the cited references explicitly disclose using a cation exchange chromatography packing material selected from POROS™ XS and/or CAPTO™ S Impact. This deficiency is remedied by Liu.
Liu discloses a method for preparing an antibody drug conjugate wherein the invention relates to the preparation of antibody drug conjugates (ADCs) using an ion exchange column as a carrier (Technical Field, Page 1). While the focus of Liu is the preparation of ADCs on a cation exchange column, Liu also teaches cation exchange chromatography has been used for ADC separation and/or purification (Page 2, First Full Paragraph). Liu further teaches that antigen-binding proteins that may be used in methods of the invention include Herceptin (i.e., trastuzumab) (Page 5, Last Paragraph). Cation exchange resins useful in the method of the invention include Millpore Fractogel SO3; Millpore Eshmuno S; Millpore Eshmuno CPX; GE Capto S Impact; GE SP Sepharose Fast Flow; HiTrapTM Capto S ImpAct (Page 18, Last Paragraph; emphasis added). Example 8 demonstrates that after production, ADCs can be eluted from the cation exchange columns (see Pages 27-28). Thus, Liu established the use of cation exchange resins (i.e., packing materials) for both ADC preparation and separation/purification.
Thus, it would have been obvious to one of ordinary skill in the art to utilize the ADC production method of instant claim 6 rendered obvious by Masuda, Talele, Nakada, Lou, and Nadkarni wherein said method could be modified to comprise a purification step, as suggested by Masuda, wherein said purification step can comprise contacting the ADC preparation with a cation exchange column, such as that suggested by Nadkarni, wherein said cation exchange column may comprise CAPTO™ S Impact packing material, as suggested by Liu, because the simple substitution of one known element for another would be expected to yield predictable results. One having ordinary skill in the art would have recognized that the production method rendered obvious by Masuda, Talele, Nakada, Lou, and Nadkarni could utilize the cationic packing material CAPTO™ S Impact for practicing cation column chromatography in the purification step because said packing material is disclosed by Liu to be useful in both ADC production and separation/purification; thus using the cationic packing material CAPTO™ S Impact for practicing cation column chromatography would reasonably be expected to successfully purify trastuzumab ADCs.
Response to Arguments - 35 USC § 103
Applicant's arguments filed 03/18/2026 (herein after referred to as "Remarks") have been fully considered but they are not persuasive.
With regard to the above-listed claim rejections under 35 U.S.C. 103, Applicant argues the following on Pages 13-16 of Remarks:
There is no expectation of success when combining any of the cited references. With regards to Masuda, in which every rejection under 35 U.S.C. §103 relies upon, the antibody-drug conjugates utilize an antibody selected from anti-87H3 antibody, antiCD30 antibody, anti-CD33 antibody, and anti-CD70 antibody, while the antibody of the present invention is the anti-HER2 antibody, trastuzumab. Furthermore, the ADCs of present invention possess a cycloalkyl substitution at the end adjacent to the drug and linker, whereas the corresponding drug structure in the conjugate examples of Masuda has no non-hydrogen substitution. Importantly, one of ordinary skill in the art is that chemical science is an experimental project, and any modification to the molecular formula, including where and what kind of modification, will affect the physicochemical properties and physiological functions of the compound. Therefore, Applicants submit that the modification of the antibody-drug conjugate of the present invention is not obvious. In addition, the reaction conditions for preparing antibody-drug conjugates disclosed in Masuda all use PBS as the buffer, whereas the present invention uses histidine buffer. Masuda has significant differences from the two antibody-drug conjugates of the present invention, both in terms of the structure of the antibody and drug, as well as the preparation method, and Masuda does not provide any enlightenment on obtaining the technical solution of the present invention. Similarly, Talele and Nakada neither disclosed the structure of the conjugate of the present invention, nor provided insights into the optimization conditions for the preparation method of the conjugate.
The instant ADCs demonstrate unexpected technical effects. Masuda does not disclose the impact of different preparation methods on drug loading distribution, while the present invention provides Test Example 2-1 Drug Loading Distribution Test (see, e.g., page 102 of the specification), comparing the effects of different preparation conditions on the drug loading of the claimed antibody-drug conjugate. According to the results in Table 6, when the reaction conditions for preparing the antibody-drug conjugate are the same as those in Masuda, (e.g., the buffer system is PBS and the reduction reaction temperature is 37 °C), the proportion of unbound antibody heavy chain (Ho) is 6%. However, when the buffer system in the present application is changed to histidine hydrochloric acid, the maximum (Ho) is 3.52%, and when the reduction reaction temperature is also 37 °C, (Ho) is only 3.32%. It can be seen that changing the buffer system for the reduction reaction significantly improves the uniformity of drug loading distribution.
Specifically regarding the first argument, it is noted that 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). It is noted that while Applicant has amended the instant claims to require a histidine salt buffer for the reduction step (a) in instant claim 1, it is noted that the deficiency of Masuda regarding such a buffer system was previously addressed by the teachings of Lou, and Applicant has provided no arguments against Lou and its teachings as pertain to reduction reaction conditions (e.g., buffer, pH, temperature, TCEP stoichiometry, etc.). The claim rejections under 35 U.S.C. 103 have been re-organized above, wherein said rejections rely on teachings previously presented. Applicant provides no arguments regarding the combination of Masuda, Zhu, Talele, and Lou nor Masuda, Talele, Nakada, and Lou. Furthermore, the motivation to combine the cited references was provided as part of the obviousness rationales, wherein the secondary references remedy the above-identified deficiencies of Masuda. Notably, there is no requirement that an “express, written motivation to combine must appear in prior art references before a finding of obviousness.” See Ruiz v. A.B. Chance Co., 357 F.3d 1270, 1276, 69 USPQ2d 1686, 1690 (Fed. Cir. 2004). The rationale to support a rejection under 35 U.S.C. 103 may rely on logic and sound scientific principle. In re Soli, 317 F.2d 941, 137 USPQ 797 (CCPA 1963). The teachings of the secondary references and the reasons for modifying Masuda based on said teachings were/are provided and rely on scientific logic.
With regard to the second argument, it is specifically noted that Lou was/is relied upon regarding the use of a histidine-based buffer system for the reduction reaction of step (a) in instant claim 1 and in view of Masuda further supports that the reaction conditions for said reduction reaction, including buffer, temperature, pH, TCEP stoichiometry, etc. are optimizable, as detailed above. Evidence of unexpected properties may be in the form of a direct or indirect comparison of the claimed invention with the closest prior art which is commensurate in scope with the claims. See In re Boesch, 617 F.2d 272, 205 USPQ 215 (CCPA 1980) and MPEP § 716.02(d) - § 716.02(e). An affidavit or declaration under 37 CFR 1.132 must compare the claimed subject matter with the closest prior art to be effective to rebut a prima facie case of obviousness. In re Burckel, 592 F.2d 1175, 201 USPQ 67 (CCPA 1979). “A comparison of the claimed invention with the disclosure of each cited reference to determine the number of claim limitations in common with each reference, bearing in mind the relative importance of particular limitations, will usually yield the closest single prior art reference.” In re Merchant, 575 F.2d 865, 868, 197 USPQ 785, 787 (CCPA 1978) (emphasis in original). Where the comparison is not identical with the reference disclosure, deviations therefrom should be explained, In re Finley, 174 F.2d 130, 81 USPQ 383 (CCPA 1949), and if not explained should be noted and evaluated, and if significant, explanation should be required. In re Armstrong, 280 F.2d 132, 126 USPQ 281 (CCPA 1960) (deviations from example were inconsequential). See also MPEP 716.02e. Specifically regarding the data presented by Applicant pertaining to unbound antibody heavy chain, it is noted that Lou discloses the percentages of unmodified antibody under various reaction conditions for IgG1 antibodies (trastuzumab as claimed is an IgG1 antibody). It is specifically noted that Table 6 of Lou indicates that both histidine and HEPES have the lowest percentages of unmodified antibody at 4.% and 4.91%, respectively, compared to succinate, PBS, and Tris at 8.4%, 9.05%, and 6.36% respectively. Additionally, Table 1 of Lou indicates that with a sufficient stoichiometric ratio of TCEP in a reduction reaction in histidine buffer, the percentage of unmodified antibody, wherein the resulting DAR ranges from 6.82-8.00, is as low as 0%. Thus, from the teachings of Lou, one of ordinary skill in the art would reasonably recognize that performing a reduction reaction is histidine buffer is preferred as it limits the amount of unmodified antibody and would therefor reasonably be expected to yield a more homogenous population of ADCs with respect to DAR. Furthermore, the teaching of Lou would also reasonably suggest to one of ordinary skill in the art that additional reaction variables such as temperature, pH, TCEP stoichiometry, etc. can be optimized to further improve the reduction reaction.
Thus, in view of the above, all of the claim rejections under 35 U.S.C. 103 are deemed proper.
Conclusion
Claims 1-6, 9, 11-12, and 16-24 are pending. Claims 1-6, 9, 11-12, and 16-24 are rejected. No claims are allowed.
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to ALYSSA RAE STONEBRAKER whose telephone number is (571)270-0863. The examiner can normally be reached Monday-Thursday 7:00 am - 5:00 pm.
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/ALYSSA RAE STONEBRAKER/Examiner, Art Unit 1642
/SAMIRA J JEAN-LOUIS/Supervisory Patent Examiner, Art Unit 1642
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