Prosecution Insights
Last updated: April 19, 2026
Application No. 17/605,343

THIOESTER CATIONIC LIPIDS

Non-Final OA §DP
Filed
Oct 21, 2021
Examiner
POPA, ILEANA
Art Unit
1633
Tech Center
1600 — Biotechnology & Organic Chemistry
Assignee
Translate Bio, Inc.
OA Round
2 (Non-Final)
21%
Grant Probability
At Risk
2-3
OA Rounds
4y 8m
To Grant
35%
With Interview

Examiner Intelligence

Grants only 21% of cases
21%
Career Allow Rate
172 granted / 820 resolved
-39.0% vs TC avg
Moderate +14% lift
Without
With
+13.9%
Interview Lift
resolved cases with interview
Typical timeline
4y 8m
Avg Prosecution
61 currently pending
Career history
881
Total Applications
across all art units

Statute-Specific Performance

§101
1.7%
-38.3% vs TC avg
§103
45.2%
+5.2% vs TC avg
§102
9.3%
-30.7% vs TC avg
§112
19.8%
-20.2% vs TC avg
Black line = Tech Center average estimate • Based on career data from 820 resolved cases

Office Action

§DP
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 . 1. Claims 3, 4, 6-14, 17, 18, 22, 23, 26-29, and 33 have been cancelled. Claims 1, 2, 5, 10, 20, 21, 24, 30-32, 34, 36, 38, and 39 have been amended. Claims 1, 2, 5, 15, 16, 19-21, 24, 25, 30-32, and 34-41 are pending and under examination. 2. All objections/rejections pertaining to claim 33 are moot because the claim was cancelled with the reply filed on 10/27/2025. The objection to claims 1, 2, 5, 15, 20, 21, 30-32, 34, 36, 38, and 39 are withdrawn in response to the amendments filed on 10/27/2025. The objection to claim 16 is withdrawn in response to applicant’s arguments. The rejection of claim 34 are under 35 U.S.C. 112(b) is withdrawn in response to the amendment to make the claim dependent upon claim 25. The rejection of claim 2 under 35 U.S.C. 112(d) or pre-AIA 35 U.S.C. 112(d) is withdrawn in response to the amendment to delete the term “each” and to replace the recitation “and/or” (line 2) with “or”. The rejection of claim 16 under 35 U.S.C. 112(d) or pre-AIA 35 U.S.C. 112(d) is withdrawn in response to applicant’s arguments. Claim Objections 3. Claim 1 is objected to because of the recitation “L1 is independently”. Since there is only one L1, correction to delete the term “independently” is required. New Rejections Double Patenting 4. 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 U SPQ 645 (Fed. Cir. 1985); In re Van Ornum, 686 F.2d 937, 214 USPQ 761 (CCPA 1982); In re V ogel, 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 § 2146 et seq. 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 filing of a terminal disclaimer by itself is not a complete reply to a nonstatutory double patenting (NSDP) rejection. A complete reply requires that the terminal disclaimer be accompanied by a reply requesting reconsideration of the prior Office action. Even where the NSDP rejection is provisional the reply must be complete. See MPEP § 804, subsection I.B.1. For a reply to a non-final Office action, see 37 CFR 1.111(a). For a reply to final Office action, see 37 CFR 1.113(c). A request for reconsideration while not provided for in 37 CFR 1.113(c) may be filed after final for consideration. See MPEP §§ 706.07(e) and 714.13. The USPTO Internet website contains terminal disclaimer forms which may be used. Please visit www.uspto.gov/patent/patents-forms. The actual 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/apply/applying- online/eterminal-disclaimer. 5. Claims 1, 2, 5, 15, 20, 21, 24, 25, 39, 31, and 34-40 are rejected on the ground of nonstatutory double patenting as being unpatentable over claims 1-17 of U.S. Patent No.12,076,439, in view of both Kazemi et al. (Journal of Sulfur Chemistry, 2015, 36: 613-623; Abstract) and Heyes et al. (WO 11/141705). Although the claims at issue are not identical, they are not patentably distinct from each other because both claim sets encompass similar thioester cationic lipids, liposomes comprising the thioester cationic lipids, and similar methods of treating a disease by using the liposomes. The instant claim 1 recites thioester cationic lipids set forth by the formula A: PNG media_image1.png 109 288 media_image1.png Greyscale , where L1 could be C1-C12 alkyl and each R1 is independently a C6-C30 aliphatic hydrocarbon chain. The patent claim 2 recites thioester cationic lipids set forth by the formula C: PNG media_image2.png 107 288 media_image2.png Greyscale , where R is a C8, C10, C12, C14, C16,or C18 aliphatic hydrocarbon chain. This structure is encompassed by the claimed formula A, except for the orientation of the thioester bond: PNG media_image3.png 43 48 media_image3.png Greyscale (instant formula A) vs PNG media_image4.png 41 48 media_image4.png Greyscale (patent claims). Thus, the only difference between the lipids recited in the instant claims and the ones recited in the patent claims is the orientation of the thioester bond. While the patent claims do not recite the claimed thioester orientation, Kazemi et al. teach that the prior art teaches that the esterification of thiols is the best and most common strategy for synthesizing thioesters; linking via a thioester bond only requires the presence of a reactant comprising a thiol and of a reactant comprising a carboxyl (see Abstract). One of skill in the art would have readily understood that the thiol and carboxyl groups can be switched between the reactants and that, based on the distribution of the groups among the reactants, the thioester bond can have one of the two orientations shown above. Furthermore, Heyes et al. teach that cationic lipids comprising a thioester bond having the claimed orientation could be obtained via the reaction between a carboxylic acid and a thiol. Heyes et al. exemplifies obtaining the cationic lipid MC3 thioester by reacting N,N-dimethylamino butyric acid with (6Z,9Z,28Z,31Z)-6,9,28,31-heptatriacontatetraene-19-thiol: PNG media_image5.png 66 192 media_image5.png Greyscale + PNG media_image6.png 57 336 media_image6.png Greyscale PNG media_image7.png 73 26 media_image7.png Greyscale PNG media_image8.png 62 384 media_image8.png Greyscale MC3 thioester having the thioester bond in the PNG media_image3.png 43 48 media_image3.png Greyscale orientation (see p. 98; p. 129, Compound 20). Based on these teachings, one of skill in the art would have viewed the PNG media_image3.png 43 48 media_image3.png Greyscale orientation as an obvious variant. Modifying the patent claims by using the claimed orientation of the thioester bond would have been obvious to one of skill in the art to achieve the predictable result of obtaining thioester cationic lipids. By doing so, one of skill in the art would have obtained Compounds 22, 29, 41, 43, 50, and 57 recited in the instant claim 20. Thus, the patent claims and the instant claims are obvious variants. 6. Claims 1 are rejected on the ground of nonstatutory double patenting as being unpatentable over claim 2 U.S. Patent No. 12,453,759, in view of both Kazemi et al. and Heyes et al. Although the claims at issue are not identical, they are not patentably distinct from each other because both claim sets encompass similar thioester cationic lipids, liposomes comprising the thioester cationic lipids, and similar methods of treating a disease by using the liposomes. The instant claim 1 recites thioester cationic lipids set forth by the formula A: PNG media_image1.png 109 288 media_image1.png Greyscale , where L1 could be C1-C12 alkyl and each R1 is independently a C6-C30 aliphatic hydrocarbon chain. The patent claim 2 recites lipids set forth by the formula C: PNG media_image9.png 106 288 media_image9.png Greyscale , where L1 is a C1-C12 aliphatic hydrocarbon chain and where R1 is a C6-C30 aliphatic hydrocarbon chain. Thus, the only difference between the lipids recited in the instant claims and the ones recited in the patent claims is the orientation of the thioester bond: PNG media_image3.png 43 48 media_image3.png Greyscale (instant formula A) vs PNG media_image4.png 41 48 media_image4.png Greyscale (patent formula C). While the patent claims do not recite the claimed thioester orientation, Kazemi et al. teach that the prior art teaches that the esterification of thiols is the best and most common strategy for synthesizing thioesters; linking via a thioester bond only requires the presence of a reactant comprising a thiol and of a reactant comprising a carboxyl (see Abstract). One of skill in the art would have readily understood that the thiol and carboxyl groups can be switched between the reactants and that, based on the distribution of the groups among the reactants, the thioester bond can have one of the two orientations shown above. Furthermore, Heyes et al. teach that cationic lipids comprising a thioester bond having the claimed orientation could be obtained via the reaction between a carboxylic acid and a thiol. Heyes et al. exemplifies obtaining the cationic lipid MC3 thioester by reacting N,N-dimethylamino butyric acid with (6Z,9Z,28Z,31Z)-6,9,28,31-heptatriacontatetraene-19-thiol: PNG media_image5.png 66 192 media_image5.png Greyscale + PNG media_image6.png 57 336 media_image6.png Greyscale PNG media_image7.png 73 26 media_image7.png Greyscale PNG media_image8.png 62 384 media_image8.png Greyscale MC3 thioester having the thioester bond in the PNG media_image3.png 43 48 media_image3.png Greyscale orientation (see p. 98; p. 129, Compound 20). Based on these teachings, one of skill in the art would have viewed the PNG media_image3.png 43 48 media_image3.png Greyscale orientation as an obvious variant. Modifying formula C recited in the patent claims by using the claimed thioester bond orientation would have been obvious to one of skill in the art to achieve the predictable result of obtaining thioester cationic lipids. By doing so, one of skill in the art would have obtained compounds as recited in the instant claim 1. Thus, the patent claims and the instant claims are obvious variants. 7. No claim is allowed. Claims 1, 2, 5, 15, 20, 21, 24, 25, 39, 31, and 34-40 are rejected. Claim 41 is objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. Any inquiry concerning this communication or earlier communications from the examiner should be directed to ILEANA POPA whose telephone number is (571)272-5546. The examiner can normally be reached 8:00 am to 4:30 pm. 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, Christopher Babic can be reached at 571-272-8507. 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. /ILEANA POPA/Primary Examiner, Art Unit 1633
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Prosecution Timeline

Oct 21, 2021
Application Filed
Jul 23, 2025
Non-Final Rejection — §DP
Oct 27, 2025
Response Filed
Jan 20, 2026
Non-Final Rejection — §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

2-3
Expected OA Rounds
21%
Grant Probability
35%
With Interview (+13.9%)
4y 8m
Median Time to Grant
Moderate
PTA Risk
Based on 820 resolved cases by this examiner. Grant probability derived from career allow rate.

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