Prosecution Insights
Last updated: April 19, 2026
Application No. 18/620,255

PROCESS FOR PURIFICATION OF FUSION PROTEIN

Non-Final OA §103§DP
Filed
Mar 28, 2024
Examiner
KIM, YUNSOO
Art Unit
1641
Tech Center
1600 — Biotechnology & Organic Chemistry
Assignee
Kashiv Biosciences LLC
OA Round
3 (Non-Final)
66%
Grant Probability
Favorable
3-4
OA Rounds
3y 9m
To Grant
99%
With Interview

Examiner Intelligence

Grants 66% — above average
66%
Career Allow Rate
600 granted / 914 resolved
+5.6% vs TC avg
Strong +35% interview lift
Without
With
+34.9%
Interview Lift
resolved cases with interview
Typical timeline
3y 9m
Avg Prosecution
62 currently pending
Career history
976
Total Applications
across all art units

Statute-Specific Performance

§101
0.1%
-39.9% vs TC avg
§103
37.0%
-3.0% vs TC avg
§102
6.6%
-33.4% vs TC avg
§112
12.5%
-27.5% vs TC avg
Black line = Tech Center average estimate • Based on career data from 914 resolved cases

Office Action

§103 §DP
DETAILED ACTION 1. The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . 2. 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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 8/11/25 has been entered. 3. Claims 1, 20-25, 27 and 29-39 are pending upon entry of amendment filed on 4/23/25. Claim 21 stands withdrawn from further consideration by the examiner, 37 CFR 1.142 (b) as being drawn to a nonelected invention. Claim 1, 21-25, 27 and 29-39 are under consideration in the instant application. 4. Applicant’s submission of IDS filed on 8/11/25 has been acknowledged. 5. The following rejection remains. 6. 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. 7. 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 of this title, 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. 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. 8. Claims 1, 21-25, 27 and 29-39 rejected under 35 U.S.C. 103(a) as being unpatentable over U.S. Pub 2013/0338344 (of record) in view of WO2019/224843 (of record) for the reasons set forth in the office action mailed on 5/9/25. The ‘344 publication teaches purification of monoclonal antibody using anion exchange chromatography in addition to cation exchange, protein A affinity chromatography with buffer at pH 7.5 (p. 2-5, 10-12). The protein concentration is about 50 to 500g/L ([0015]) using large batch and claim 22 is included in this rejection. In addition, the wash or elution buffer concentration is about 50mM with conductivity of about 5mS/cm (p. 3, Table 1, 2 p. 12). Further, the ‘344 publication teaches use of anionic exchange column using Poros XQ with linear gradient of buffer (Figures) and the buffer includes NaCl, sodium phosphate with column volume of 5-20CV (Examples). The disclosure of the ‘344 publication differs from the instant claimed invention in that it does not teach the use 344 CTLA4-IgG1 fusion protein as inn claims 1 and 23 of the instant application. The ‘843 publication teaches use of CTLA4-Ig using protein A in addition to any downstream process (p. 11) to improve purity. Given that the CTLA-Ig fusion protein prepared under anion exchange, protein A and additional chromatographic methods, the method would expect to reduce high mannose as in claims 1 and 21 and comprise mannose range of 0.05-0.3% as in claim 3. One of ordinary skill in the art at the time the invention was made would have been motivated to do so because the utilization of anion and affinity chromatographic method known to various antibody without denaturing protein and known methods/condition for anion/affinity chromatography would be helpful to optimize CTLA4-Ig fusion protein purification improving purity and stability. From the teachings of references, it would have been obvious to one of ordinary skill in art to combine the teachings of the references and there would have been a reasonable expectation of success in producing the claimed invention. Therefore, the invention as a whole was prima facie obvious to one of the ordinary in the art at the time of invention was made, as evidenced by the references, especially in the absence of evidence to the contrary. Applicant’s response filed on 8/11/25 has been fully considered but they were not persuasive. Applicant has asserted that the currently amended limitations are not taught by the references. Applicant has further asserted that the ‘344 publication teaches monoclonal antibody but no CTLA4-Ig fusion has not been taught and the ‘843 publication does not teach anion-exchange chromatography. IN addition, Applicant has asserted that the pH range of 7-7.5 has not been taught by the references but pH 8.2-9.0 This is formulated as a new rejection as the claim numbers were not correctly added. Note claims 21-25, 27 and 29-39 are added in this rejection. However, unlike Applicant’s assertion that the ‘344 publication does not teach pH 8.2-9.1, the ‘344 publication discloses pH between 7-8.2 inclusive of pH 7.5 (p.2, [0013]). Applicant is reminded that the use of patent as reference is not limited to what the patentee described as their own invention or to the problems with which they are concerned. See MPEP2123. In addition, the ‘344 publication discloses antibody to include various fragments (p.4-6) as well as bispecific and DvD-Ig that readable upon fusion including Ig as in instant application (p. 4, [0060]). As such, the reference teachings provide reasonable expectation of success in combining the references. Applicant is reminded that the rejection is based on the combination of the references. One cannot show nonobviousness by attacking references individually where the rejection is based on the combination of the references. The ‘344 publication teaches anion exchange and the ‘843 publication teaches CTLA4-Ig fusion. Given that the purification is not limited to anion exchange chromatography but allows other purification steps as the transition word “comprises” is used. Further, in lack of specifying experimental conditions, the anion-exchange chromatography is expected to reduce high mannose content and meets the limitations. As such, the combination of the references remains obvious and the rejection is maintained. 9. The nonstatutory double patenting rejection is based on a judicially created doctrine grounded in public policy (a policy reflected in the statute) so as to prevent the unjustified or improper timewise extension of the “right to exclude” granted by a patent and to prevent possible harassment by multiple assignees. A nonstatutory double patenting rejection is appropriate where the conflicting claims are not identical, but at least one examined application claim is not patentably distinct from the reference claim(s) because the examined application claim is either anticipated by, or would have been obvious over, the reference claim(s). See, e.g., In re Berg, 140 F.3d 1428, 46 USPQ2d 1226 (Fed. Cir. 1998); In re Goodman, 11 F.3d 1046, 29 USPQ2d 2010 (Fed. Cir. 1993); In re Longi, 759 F.2d 887, 225 USPQ 645 (Fed. Cir. 1985); In re Van Ornum, 686 F.2d 937, 214 USPQ 761 (CCPA 1982); In re Vogel, 422 F.2d 438, 164 USPQ 619 (CCPA 1970); In re Thorington, 418 F.2d 528, 163 USPQ 644 (CCPA 1969). A timely filed terminal disclaimer in compliance with 37 CFR 1.321(c) or 1.321(d) may be used to overcome an actual or provisional rejection based on nonstatutory double patenting provided the reference application or patent either is shown to be commonly owned with the examined application, or claims an invention made as a result of activities undertaken within the scope of a joint research agreement. See MPEP § 717.02 for applications subject to examination under the first inventor to file provisions of the AIA as explained in MPEP § 2159. See MPEP §§ 706.02(l)(1) - 706.02(l)(3) for applications not subject to examination under the first inventor to file provisions of the AIA . A terminal disclaimer must be signed in compliance with 37 CFR 1.321(b). The USPTO Internet website contains terminal disclaimer forms which may be used. Please visit www.uspto.gov/patent/patents-forms. The filing date of the application in which the form is filed determines what form (e.g., PTO/SB/25, PTO/SB/26, PTO/AIA /25, or PTO/AIA /26) should be used. A web-based eTerminal Disclaimer may be filled out completely online using web-screens. An eTerminal Disclaimer that meets all requirements is auto-processed and approved immediately upon submission. For more information about eTerminal Disclaimers, refer to www.uspto.gov/patents/process/file/efs/guidance/eTD-info-I.jsp. 10. Claims 1, 21-25, 27 and 29-39 are provisionally rejected on the ground of nonstatutory double patenting as being unpatentable over claims 1-36 of U.S. Application No. 17/922,734. Although the claims at issue are not identical, they are not patentably distinct from each other because the claims of the ‘734 application recites methods of purifying CTLA1-IgG with affinity and anion exchange chromatograph and reduce high mannose content as in claimed method. This is a provisional nonstatutory double patenting rejection because the patentably indistinct claims have not in fact been patented. As Applicant has requested that this double patenting rejection be held in abeyance until patentable subject matter has been identified in the instant application, the double patenting rejection is maintained. 11. No claims are allowed. 12. Any inquiry concerning this communication or earlier communications from the examiner should be directed to YUNSOO KIM whose telephone number is (571)272-3176. The examiner can normally be reached Mon-Fri 8:30-5. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Misook Yu can be reached on 571-272-0839. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. Yunsoo Kim Patent Examiner Technology Center 1600 October 28, 2025 /YUNSOO KIM/Primary Examiner, Art Unit 1641
Read full office action

Prosecution Timeline

Mar 28, 2024
Application Filed
Jan 17, 2025
Non-Final Rejection — §103, §DP
Apr 23, 2025
Response Filed
May 05, 2025
Final Rejection — §103, §DP
Aug 11, 2025
Request for Continued Examination
Aug 13, 2025
Response after Non-Final Action
Oct 28, 2025
Non-Final Rejection — §103, §DP (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

3-4
Expected OA Rounds
66%
Grant Probability
99%
With Interview (+34.9%)
3y 9m
Median Time to Grant
High
PTA Risk
Based on 914 resolved cases by this examiner. Grant probability derived from career allow rate.

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