Prosecution Insights
Last updated: October 27, 2026
Application No. 19/407,141

LIGAND-DRUG CONJUGATES

Final Rejection §102§112
Filed
Dec 03, 2025
Priority
Dec 04, 2024 — provisional 63/728,044
Examiner
PUTTLITZ, KARL J
Art Unit
1646
Tech Center
1600 — Biotechnology & Organic Chemistry
Assignee
Tripartite Therapeutics Inc.
OA Round
2 (Final)
69%
Grant Probability
Favorable
3-4
OA Rounds
1y 7m
Est. Remaining
88%
With Interview

Examiner Intelligence

Grants 69% — above average
69%
Career Allowance Rate
992 granted / 1434 resolved
+9.2% vs TC avg
Strong +18% interview lift
Without
With
+18.5%
Interview Lift
resolved cases with interview
Typical timeline
2y 6m
Avg Prosecution
61 currently pending
Career history
1501
Total Applications
across all art units

Statute-Specific Performance

§101
1.6%
-38.4% vs TC avg
§103
36.5%
-3.5% vs TC avg
§102
11.5%
-28.5% vs TC avg
§112
28.7%
-11.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1434 resolved cases

Office Action

§102 §112
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 . The rejection under obvious double patenting is withdrawn in view of Applicant’s amendments and remarks. The rejection under Improper Markush Grouping is moot. The following is a new ground of rejection under this section, which was necessitated by Applicant’s amendments: Claim Rejections - Rejection under the Judicially Created Doctrine of Improper Markush Grouping Claims 28-36 are rejected on the basis that it contains an improper Markush grouping of alternatives. See In re Harnisch, 631 F.2d 716, 721-22 (CCPA 1980) and Ex parte Hozumi, 3 USPQ2d 1059, 1060 (Bd. Pat. App. & Int. 1984). A Markush grouping is proper if the alternatives defined by the Markush group (i.e., alternatives from which a selection is to be made in the context of a combination or process, or alternative chemical compounds as a whole) share a “single structural similarity” and a common use. A Markush grouping meets these requirements in two situations. First, a Markush grouping is proper if the alternatives are all members of the same recognized physical or chemical class or the same art-recognized class, and are disclosed in the specification or known in the art to be functionally equivalent and have a common use. Second, where a Markush grouping describes alternative chemical compounds, whether by words or chemical formulas, and the alternatives do not belong to a recognized class as set forth above, the members of the Markush grouping may be considered to share a “single structural similarity” and common use where the alternatives share both a substantial structural feature and a common use that flows from the substantial structural feature. See MPEP § 2117. The doctrine of improper Markush grouping is a principle that prevents applicants from claiming widely disparate alternatives in a single "Markush-style" claim. To be proper, grouped elements must share a single structural similarity and possess a common use. The examiner respectfully directs the Applicant's attention to MPEP 803.02 shown below for convenience: "A Markush-type claim recites alternatives in a format such as "selected from the group consisting of A, Band C." See Ex parte Markush, 1925 C.D. 126 (Comm'r Pat. 1925). The members of the Markush group (A, B, and C in the example above) ordinarily must belong to a recognized physical or chemical class or to an art-recognized class. However, when the Markush group occurs in a claim reciting a process or a combination (not a single compound), it is sufficient if the members of the group are disclosed in the specification to possess at least one property in common which is mainly responsible for their function in the claimed relationship, and it is clear from their very nature or from the prior art that all of them possess this property. Inventions in metallurgy, refractories, ceramics, pharmacy, pharmacology and biology are most frequently claimed under the Markush formula but purely mechanical features or process steps may also be claimed by using the Markush style of claiming. (See MPEP § 2173.05(h))." Furthermore, the members of a proper Markush grouping " ... ordinarily must belong to a recognized physical or chemical class or to an art-recognized class." MPEP 803.02 also states that members of a Markush grouping are " ... sufficiently few in number or so closely related that a search and examination of the entire claim can be made without serious burden." This paragraph of the MPEP is shown below for convenience: "If the members of the Markush group are sufficiently few in number or so closely related that a search and examination of the entire claim can be made without serious burden, the examiner must examine all the members of the Markush group in the claim on the merits, even though they may be directed to independent and distinct inventions. In such a case, the examiner will not follow the procedure described below and will not require provisional election of a single species. (See MPEP § 808.02.)" A Markush claim contains an "improper Markush grouping" if: 1. The species of the Markush group do not share a "single structural similarity," - Meaning they do not belong to the same recognized physical or chemical class or same art-recognized class (see explanation supra), or 2. The species do not share a common use, - Meaning they are not disclosed in the specification or known in the art to be functionally equivalent. If 1 or 2 above apply to a Markush grouping, a rejection under the judicially approved "improper Markush grouping" doctrine is proper. The formulas in the rejected claims do not share a "single structural similarity" since there is no common core due to the wide range of compounds possible given variables. For a Markush grouping to be proper, the alternatives represented by the grouping must have a "significant structural element that is shared by all of the alternatives" or the species must all share a common use and recognized as "functionally equivalent". A significant structural element that is shared by all of the alternatives refers to cases where the compounds share a common chemical structure which occupies a large portion of their structures, or in case the compounds have in common only a small portion of their structures, the commonly shared structure constitutes a structurally distinctive portion in view of existing prior art, and the common structure is essential to the common property or activity. Each alternative does not have a common chemical structure which occupies a large portion of the structure or have a structurally distinctive portion in view of the prior art which is essential to the claimed common activity/properties. The formulas in the rejected claims do have common structure that occupies a large portion of their structures. Additionally, as a result of the wide range of compounds possible by the instant Markush formulas, each compound does not belong to the same recognized physical or chemical class or to the same art-recognized class and no credible evidence for a common use amongst all claimed compounds exists. A person of ordinary skill in the art would understand that compounds with such greatly varied structure cannot be expected to have predictable properties. This is a central concept to basic organic chemistry and common knowledge of those with ordinary skill in the art and taught in the first chapter of the organic text CAREY, FA. Organic Chemistry 6th Ed. McGraw Hill. 2006, chapter 1, p. 9. Therefore, in the absence of evidence to the contrary, all compounds within the metes and bounds of the extraordinarily large Markush grouping of the instant claims cannot be individually envisioned and each expected to be functionally equivalent. This rejection may be overcome by either amending the claims to include only the species that share a single structural similarity and a common use such as the compounds which have a constant core and are clearly enabled by the instant specification. The claims still recite compounds wherein a significant structural element that occupies a large portion of their structures and is shared by all the alternatives is missing. The recited groups are still variable. The rejection under section 112(a) is moot. The following is a new ground of rejection under this section, which was necessitated by Applicant’s amendments: Claim Rejections - 35 USC § 112 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 28-36 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. The rejected claims cover compounds covered by generic formulas. To satisfy the written-description requirement, the specification must describe every element of the claimed invention in sufficient detail so that one of ordinary skill in the art would recognize that the inventor possessed the claimed invention at the time of filing. Vas-Cath, 935 F.3d at 1563; see also Lockwood v. American Airlines, Inc., 107 F.3d 1565, 1572 (Fed. Cir. 1997) (patent specification must describe an invention and do so in sufficient detail that one skilled in the art can clearly conclude that “the inventor invented the claimed invention”); In re Gosteli, 872 F.2d 1008, 1012 (Fed. Cir. 1989) (“the description must clearly allow persons of ordinary skill in the art to recognize that [the inventor] invented what is claimed”). With regard to the recited genus of compounds, the following applies: Ariad Pharmaceuticals Inc. v. Eli Lilly & Co., 94 USPQ2d 1161 (Fed. Cir. 2010) states that “...a generic claim may define the boundaries of a vast genus of chemical compounds...the question may still remain whether the specification, including the original claim language, demonstrates that the applicant invented species sufficient to support a claim to a genus”. See page 1171. The written description requirement for a claimed genus may be satisfied through sufficient description of a representative number of species by actual reduction to practice, reduction to drawings, or by disclosure of relevant, identifying characteristics, i.e., structure or other physical and/or chemical properties, by functional characteristics coupled with a known or disclosed correlation between function and structure, or by a combination of such identifying characteristics, sufficient to show the applicant was in possession of the claimed genus. See Eli Lilly, 119 F.3d at 1568, 43 USPQ2d at 1406. See also Fujikawa v. Wattanasin, 93 F.3d 1559, 1571, 39 USPQ2d 1895, 1905 (Fed. Cir. 1996) (a “laundry list” disclosure of every possible moiety 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. Amgen, Inc. v. Chugai Pharmaceutical Co., Ltd., 927 F.2d 1200, 1206, 18 USPQ2d 1016, 1021 (Fed. Cir. 1991) states that “it is well established in our law that conception of a chemical compound requires that the inventor be able to define it so as to distinguish it from other materials, and to describe how to obtain it”. A description of a genus may be achieved by means of a recitation of a representative number of species falling within the scope of the genus or structural features common to the members of the genus, which features constitute a substantial portion of the genus, so that one of skill in the art can “visualize or recognize” the members of the genus (Emphasis added). Regents of the University of California v. Eli Lilly & Co., 119 F3d 1559, 1569, 43 USPQ2d 1398, 1406 (Fed. Cir. 1997). A “representative number of species” means that the species which are adequately described are representative of the entire genus. Thus, when there is substantial variation within the genus, one must describe a sufficient variety of species to reflect the variation within the genus. The disclosure of only one species encompassed within a genus adequately describes a claim directed to that genus only if the disclosure “indicates that the patentee has invented species sufficient to constitute the gen[us].” See Enzo Biochem, 323 F.3d at 966, 63 USPQ2d at 1615; Noelle v. Lederman, 355 F.3d 1343, 1350, 69 USPQ2d 1508, 1514 (Fed. Cir. 2004) (Fed. Cir. 2004)(“[A] patentee of a biotechnological invention cannot necessarily claim a genus after only describing a limited number of species because there may be unpredictability in the results obtained from species other than those specifically enumerated.”). “A patentee will not be deemed to have invented species sufficient to constitute the genus by virtue of having disclosed a single species when ... the evidence indicates ordinary artisans could not predict the operability in the invention of any species other than the one disclosed.” In re Curtis, 354 F.3d 1347, 1358, 69 USPQ2d 1274, 1282 (Fed. Cir. 2004). In Regents of the University of California v. Eli Lilly (43 USPQ2d 1398-1412), the court held that a generic statement which defines a genus of nucleic acids by only their functional activity does not provide an adequate written description of the genus. The court indicated that, while applicants are not required to disclose every species encompassed by a genus, the description of the genus is achieved by the recitation of a representative number of species falling within the scope of the claimed genus. At section B(i), the court states, "An adequate written description of a DNA ... requires a precise definition, such as by structure, formula, chemical name, or physical properties, not a mere wish or plan for obtaining the claimed chemical invention." Courts have stated that “[i]n claims involving [non-genetic] chemical materials, generic formulae usually indicate with specificity what the generic claims encompass. One skilled in the art can distinguish such a formula from others and can identify many of the species that the claims encompass. Accordingly, such a formula is normally an adequate description of the claimed genus.” Regents of the University of California v. Eli Lilly & Co., 119 F.3d 1559, 1568 (Fed. Cir. 1997), cert. denied, 523 U.S. 1089 (1998). (emphasis added). There is no such specificity here, nor could one skilled in the art identify particular compounds encompassed by the claims, given the breadth of the recited formulas. Specifically, Applicant fails to disclose any other compound species, besides those covered by the species in the specification, and in relation to the above, these disclosed species do not represent the substantial variety covered by the genus of compounds covered by the generic formulas in the specification. With regard to the functional definitions of the moieties in the claims, the specification does not clearly allow persons of ordinary skill in the art to recognize that he or she invented what is claimed (see Vas-Cath at page 1116) because the specification contains almost no information by which a person of ordinary skill in the art would understand that the inventors possessed the all of the recited compounds. At best, it simply indicates that one should test an inordinate number of groups to see if the groups can perform the required functions. In this connection, the specification contains no generic structural characteristics that can perform the required functions, see In re ’318 Patent Infringement Litigation, 583 F.3d 1317, 1327 (Fed. Cir. 2009) (“[A]t the end of the day, the specification, even read in light of the knowledge of those skilled in the art, does no more than state a hypothesis and propose testing to determine the accuracy of that hypothesis. That is not sufficient.”). The Examiner acknowledges that a working example or exemplified embodiment is not necessarily a requirement for description. However, where a generic claim term is present in a claim, as in the present application, and defined only by functional characteristics, the specification must convey enough information, e.g., via sufficient representative examples, to indicate invention of species sufficient to constitute the genus. Enzo Biochem, Inc. v. Gen-Probe Inc., 323 F.3d 956, 967 2 (Fed. Cir. 2002). The written description requirement “requires a description of an invention, not an indication of a result that one might achieve if one made that invention.” Regents of the University of California v. Eli Lilly & Co., 119 F.3d 1559, 1568 (Fed. Cir. 1997); see also Novozymes A/S v. DuPont Nutrition Biosciences APS, 723 F.3d 1336, 1350 (Fed. Cir. 2013) (“A patent...‘is not a reward for the search, but compensation for its successful conclusion.’ ... For that reason, the written description requirement prohibits a patentee from ‘leaving it to the ... industry to complete an unfinished invention.’” (citations omitted)). Accordingly, the specification lacks adequate written description for the recited compounds covered by the generic formulas in the claims. The following do not have any generic structural description: RU1, RU2, RU3, L1, L2, L3, HP1, HP2, LL, BC, HP1, HP2 and the connectors. As outlined above, the specification contains no generic structural characteristics that can perform the required functions. The rejections under section 112(b) are withdrawn in view of Applicant’s amendments and remarks. The following are new grounds of rejection under this section, which were necessitated by Applicant’s amendments: 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 28-38 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. It is unclear how the listed groups for MN1 can be divalent when these groups must bind 4 or more groups. Therefore, the structure of the recited compounds is unclear. The rejection under section 102 is withdrawn in view of Applicant’s amendments. The following are new grounds of rejection under this section: Claim Rejections - 35 USC § 102 The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention. (a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention. Claims 28-32, 34-36 are rejected under 35 U.S.C. 102(a)(1) or 102(a)(2) as being anticipated by U.S. Publication No. 20230092679 based on an application by Burger et al. (Burger). Burger teaches the following linker-drug at page 64 that anticipates the rejected claims within the meaning of section 102: PNG media_image1.png 246 438 media_image1.png Greyscale Claims 28-36 are rejected under 35 U.S.C. 102(a)(1) or 102(a)(2) as being anticipated by U.S. Publication No. 20260061065 based on an application by Burger et al. (Burger II). Burger II teaches the following linker-drug at page 145 that anticipates the rejected claims within the meaning of section 102: PNG media_image2.png 222 532 media_image2.png Greyscale D1 and D2 include the recited drug moieties, see pages 18+. 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. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to KARL J PUTTLITZ whose telephone number is (571)272-0645. The examiner can normally be reached on Monday to Friday from 9 a.m. to 5 p.m. If attempts to reach the examiner by telephone are unsuccessful, the examiner's supervisor, Gregory Emch, can be reached at telephone number 571-272-8149. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of an application may be obtained from the Patent Application Information Retrieval (PAIR) system. Status information for published applications may be obtained from either Private PAIR or Public PAIR. Status information for unpublished applications is available through Private PAIR only. For more information about the PAIR system, see http://pair-direct.uspto.gov. Should you have questions on access to the Private PAIR system, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). /KARL J PUTTLITZ/ Primary Examiner, Art Unit 1646
Read full office action

Prosecution Timeline

Dec 03, 2025
Application Filed
Jun 05, 2026
Non-Final Rejection mailed — §102, §112
Sep 04, 2026
Response Filed
Sep 30, 2026
Final Rejection mailed — §102, §112
Oct 26, 2026
Interview Requested

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Prosecution Projections

3-4
Expected OA Rounds
69%
Grant Probability
88%
With Interview (+18.5%)
2y 6m (~1y 7m remaining)
Median Time to Grant
Moderate
PTA Risk
Based on 1434 resolved cases by this examiner. Grant probability derived from career allowance rate.

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