Prosecution Insights
Last updated: April 19, 2026
Application No. 17/909,260

IMIDAZOLE-BASED SYNTHETIC LIPIDOIDS FOR IN VIVO MRNA DELIVERY INTO IMMUNE CELLS

Final Rejection §103§112
Filed
Sep 02, 2022
Examiner
MARTIN, KEVIN STEPHEN
Art Unit
1624
Tech Center
1600 — Biotechnology & Organic Chemistry
Assignee
Trustees Of Tufts College
OA Round
2 (Final)
74%
Grant Probability
Favorable
3-4
OA Rounds
3y 6m
To Grant
97%
With Interview

Examiner Intelligence

Grants 74% — above average
74%
Career Allow Rate
96 granted / 129 resolved
+14.4% vs TC avg
Strong +23% interview lift
Without
With
+23.0%
Interview Lift
resolved cases with interview
Typical timeline
3y 6m
Avg Prosecution
36 currently pending
Career history
165
Total Applications
across all art units

Statute-Specific Performance

§101
1.3%
-38.7% vs TC avg
§103
23.6%
-16.4% vs TC avg
§102
16.2%
-23.8% vs TC avg
§112
40.2%
+0.2% vs TC avg
Black line = Tech Center average estimate • Based on career data from 129 resolved cases

Office Action

§103 §112
Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Status of Claims and Response to Amendments The amendments filed November 18, 2025 have been acknowledged and entered. Claims 61-64 and 66-80 are pending. Election/Restriction The present examination is based on Applicant’s election without traverse of the species of Formula (I) corresponding to 9322-O17S (pictured below for convenience) in the reply filed on July 11, 2025. Applicant amendments have overcome the previous art rejections. New art has been found based on the search provided in the previous office action mailed August 18, 2025. The search has thus been limited to subgenus indicated previously which corresponds to Formula (I) wherein one R5 is - L-W-Rlipid; W is NR20 wherein R20 is Rlipid; and each Rlipid is Formula (II) PNG media_image1.png 134 527 media_image1.png Greyscale wherein R1 and R2 are H; p is 1; R3 and R4 taken together form oxo; Z is O; and m is 1; or each Rlipid is selected from the groups consisting of PNG media_image2.png 106 550 media_image2.png Greyscale Claims 61-64 and 66-80 (all in part, other than the above indicated subgenus) are additionally withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected species. Withdrawn Rejections Applicant is notified that any outstanding rejection or objection that is not expressly maintained in this Office Action has been withdrawn or rendered moot in view of Applicant’s amendments and/or remarks. Claim Objections and Allowable Subject Matter Claims 68, 70 and 80 are objected to because of the following informalities: Claim 68 recites structures PNG media_image3.png 98 362 media_image3.png Greyscale which appear to be typographical errors for the reason that the claim requires PNG media_image4.png 87 166 media_image4.png Greyscale . Claim 70 depends from claim 68 and includes this mistake. Appropriate correction is required. Claim 80 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. The following is a statement of reasons for the indication of allowable subject matter: The closest references to the instant claims are Nguyen et al., Li et al., and Wang et al. which are discussed in the rejections herein. The references do not teach wherein R5 is a methyl group or wherein L is PNG media_image5.png 63 84 media_image5.png Greyscale which are required by the instant claims. There is no teaching which would have motivated one of ordinary skill in the art before the effective filing date of the instant application to modify any of the reference compounds into the claimed invention with any reasonable expectation of success. Maintained Rejections Claim Rejections - 35 USC § 112b Claims 68 and 70 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. The claims are indefinite for the reasons that follow: Claim 68 recites the limitation PNG media_image6.png 94 197 media_image6.png Greyscale is PNG media_image7.png 118 217 media_image7.png Greyscale . There is insufficient antecedent basis for the limitation because claim 68 depends from claim 61 which does not provide that two R5 may form a fused aryl ring. Claim 61 recites R5 is aryl. The claim does not clearly provide support for wherein two R5 groups form a ring. The scope of the claims is therefore unclear. Claims 70 depends from claim 68, fails to cure this deficiency, and therefore is also indefinite. Response to Arguments Applicant’s arguments filed November 18, 2025 have been fully considered but they are not persuasive. Applicant states they have amended the claims to address claim language which was objected to and the amended claims are clear to the skilled artisan (page 1 of remarks). This is not found persuasive as the amendments and Applicant remarks do not address the rejection. The structure PNG media_image7.png 118 217 media_image7.png Greyscale corresponds to Formula (I) wherein two R5 form a fused ring which is not supported by the base claim 61. The rejection is still deemed proper and thus maintained. Rejections Necessitated by Applicant Amendment Claim Rejections - 35 USC § 112a The following is a quotation of the first paragraph of 35 U.S.C. 112(a): (a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention. The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112: The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention. Claims 61-64 and 66-69, 71-79 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. Claim 61 has been amended to recite limitations to Formula (I) which are not supported by the specification as filed. The claim recites: PNG media_image8.png 200 946 media_image8.png Greyscale The specification teaches R5 can be alkyl, alkenyl, alknyl, cycloalkyl, heterocycloalkyl or aryl (pages 4-5); however, there is no support in the specification for the narrow range claimed (e.g. C1-10 alkoxy, C1-6 alkyl, C2-6 alkynyl, C5-7 cycloalkyl, C6 aryl). Nor is there any support for wherein each of these groups is substituted with hydroxyl, halo, nitro, silyl, amino, or cyano. The limitations alkyl, alkenyl, alknyl, cycloalkyl, heterocycloalkyl or aryl are incredibly broad and nothing in the specification would reasonably guide a person skilled in the art to the much narrower scope of alkyl, alkenyl, alknyl, cycloalkyl, heterocycloalkyl or aryl set forth in the amended claim. “The introduction of claim changes which involve narrowing the claims by introducing elements or limitations which are not supported by the as-filed disclosure is a violation of the written description requirement of 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph. See, e.g., Fujikawa v. Wattanasin, 93 F.3d 1559, 1571, 39 USPQ2d 1895, 1905 (Fed. Cir. 1996) (a "laundry list" disclosure of every possible moiety for every possible position does not constitute a written description of every species in a genus because it would not "reasonably lead" those skilled in the art to any particular species); and Regents of the Univ. of Minnesota v. Gilead Scis., Inc., 61 F.4th 1350, 1356-58, 2023 USQ2d 269 (Fed. Cir. 2023).” Regarding Z, claim 61 has been amended to recite Z is CH2; however, the specification only provides support for wherein Z is O, NR30 or S (see page 5, lines 15-20). Accordingly, a person skilled in the art would not recognize that Applicant was in possession of the invention at the time the application was filed. Claim Rejections - 35 USC § 112b 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. Claim 66 is 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. Claim 66 depends from canceled claim 65. The scope of the claim is therefore unclear. The claim should be amended to depend from a claim that is not cancelled. Claim Rejections - 35 USC § 103 The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. The factual inquiries 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. Claim(s) 61-64, 66, 68, 71-72, 74-75 and 78-79 are rejected under 35 U.S.C. 103 as being unpatentable over Nguyen et al. (PNAS 2012 E797-803 and Supporting Information) (hereinafter “Nguyen”). Nguyen teaches a lipidoid compound (see Figures S1A and C, product of alkyl acrylate LD(12) and amine 93; structure pictured below; see CAS STNext abstract for PNAS 2012 E797-803) which corresponds to instant Formula (I) wherein the R5 attached to N is -L-W-Rlipid; the other R5 groups are H; L is a divalent linker corresponding to C3 alkylene; W is NR20 wherein R20 is Rlipid; and each Rlipid corresponds to a C2 alkyl substituted with an ester group or Formula (II) PNG media_image1.png 134 527 media_image1.png Greyscale wherein R1 and R2 are H; R3 and R4 taken together form oxo; Z is O; X and Y are CH2; m is 1; n is 1; t is 0; and q is 3. Nguyen teaches the lipidoid compound has use in delivery of RNA for treating influenza (Abstract). PNG media_image9.png 200 400 media_image9.png Greyscale The claims differ from the prior art in that the instant claims require that L is a C1, C2 or C4 alkylene linker corresponding to PNG media_image10.png 33 77 media_image10.png Greyscale , PNG media_image11.png 40 227 media_image11.png Greyscale . The instant claims are thus homologs of the prior art, differing only in the number of repeating -CH2- groups. Compounds which are homologs (compounds differing regularly by the successive addition of the same chemical group, e.g., by -CH2- groups) are generally of sufficiently close structural similarity that there is a presumed expectation that such compounds possess similar properties. See MPEP 2144.09. It has been long established that structural relationship varying the size of a linking carbon chain - is per se obvious. Specifically, In re Shetty, 195 USPQ 753, In re Wilder, 195 USPQ 426 and Ex Parte Greshem 121 USPQ 422 all feature a compound with a C2 link rejected over a compound with a C1 link. Similarly, In re Chupp, 2 USPQ 2nd 1437 and In re Coes, 81 USPQ 369 have a C1 link unpatentable over a C2 link. Ex parte Ruddy 121 USPQ 427 has a C3 link unpatentable over a C1 link. Ex parte Nathan, 121 USPQ 349 found the insertion of a C2H4 link obvious. In all of these cases, the variation was per-se obvious and did not require a specific teaching. One would have been motivated as a matter of preparing additional lipidoid compounds for treating influenza. One would have had a reasonable expectation of success in preparing the claimed compounds because homologs are presumed to have the same activity. Claim(s) 61-64, 66, 68, 70-72 and 74-79 are rejected under 35 U.S.C. 103 as being unpatentable over Li et al. (Biomaterials 2018 652-662) (hereinafter “Li”) Li teaches a compound (see Figure 1B, product of O17X wherein X is S and amine 93; pictured below; see CAS STNext abstract for Li et al. Biomaterials 2018 652-662) which corresponds to instant Formula (I) wherein the R5 attached to N is -L-W-Rlipid; the other R5 groups are H; L is a divalent linker corresponding to C3 alkylene; W is NR20 wherein R20 is Rlipid; and each Rlipid is PNG media_image12.png 73 331 media_image12.png Greyscale . Li teaches the compound is useful for delivery of therapeutics. PNG media_image13.png 200 400 media_image13.png Greyscale The claims differ from the prior art in that the instant claims require that L is a C1, C2 or C4 alkylene linker corresponding to PNG media_image10.png 33 77 media_image10.png Greyscale , PNG media_image11.png 40 227 media_image11.png Greyscale . The instant claims are thus homologs of the prior art, differing only in the number of repeating -CH2- groups. The instant claims would have been prima facie obvious to one having ordinary skill in the art before the effective filing date of the instant invention for the reasons provided in the rejection over Nguyen above which are incorporated herein by reference. Claim(s) 61-64, 66, 68, 71-73 and 76 are rejected under 35 U.S.C. 103 as being unpatentable over Wang et al. (ACIE 2014, 53, 2893-2898). Wang teaches a compound EC16-2 (see Figure 1; Figure 2; product of amine 2 and EC16; The lipidoids are named EC16 followed by amine number; pictured below for convenience) which corresponds to instant Formula (I) wherein the R5 attached to N is -L-W-Rlipid; the other R5 groups are H; L is a divalent linker corresponding to C3 alkylene; W is NR20 wherein R20 is Rlipid; and each Rlipid corresponds to PNG media_image14.png 97 240 media_image14.png Greyscale . Wang teaches the compound is useful for delivery of therapeutics (Abstract). PNG media_image15.png 177 275 media_image15.png Greyscale The claims differ from the prior art in that the instant claims require that L is a C1, C2 or C4 alkylene linker corresponding to PNG media_image10.png 33 77 media_image10.png Greyscale , PNG media_image11.png 40 227 media_image11.png Greyscale . The instant claims are thus homologs of the prior art, differing only in the number of repeating -CH2- groups. The instant claims would have been prima facie obvious to one having ordinary skill in the art before the effective filing date of the instant invention for the reasons provided in the rejection over Nguyen above which are incorporated herein by reference. Conclusion No claim is 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 KEVIN MARTIN whose telephone number is (571)270-0917. The examiner can normally be reached Monday - Friday 8 am - 5 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, Jeffrey Murray can be reached on (571) 272-9023. 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. January 26, 2026 /K.S.M./Examiner, Art Unit 1624 /BRUCK KIFLE/Primary Examiner, Art Unit 1624
Read full office action

Prosecution Timeline

Sep 02, 2022
Application Filed
Aug 10, 2025
Non-Final Rejection — §103, §112
Nov 18, 2025
Response Filed
Jan 26, 2026
Final Rejection — §103, §112 (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
74%
Grant Probability
97%
With Interview (+23.0%)
3y 6m
Median Time to Grant
Moderate
PTA Risk
Based on 129 resolved cases by this examiner. Grant probability derived from career allow rate.

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