Prosecution Insights
Last updated: July 17, 2026
Application No. 17/910,497

NOVEL CAS ENZYMES AND METHODS OF PROFILING SPECIFICITY AND ACTIVITY

Non-Final OA §112
Filed
Sep 09, 2022
Priority
Mar 11, 2020 — provisional 62/988,037 +2 more
Examiner
CHONG, KIMBERLY
Art Unit
1636
Tech Center
1600 — Biotechnology & Organic Chemistry
Assignee
Massachusetts Institute of Technology
OA Round
3 (Non-Final)
72%
Grant Probability
Favorable
3-4
OA Rounds
0m
Est. Remaining
85%
With Interview

Examiner Intelligence

Grants 72% — above average
72%
Career Allowance Rate
1078 granted / 1488 resolved
+12.4% vs TC avg
Moderate +13% lift
Without
With
+12.6%
Interview Lift
resolved cases with interview
Typical timeline
2y 6m
Avg Prosecution
65 currently pending
Career history
1551
Total Applications
across all art units

Statute-Specific Performance

§101
1.4%
-38.6% vs TC avg
§103
41.8%
+1.8% vs TC avg
§102
9.1%
-30.9% vs TC avg
§112
26.4%
-13.6% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1488 resolved cases

Office Action

§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 . DETAILED ACTION Request for Continued Examination 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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 03/03/2026 has been entered. Status of Application/Amendment/Claims Applicant's response filed 03/03/2026 has been considered. Rejections and/or objections not reiterated from the previous office action mailed 12/08/2025 are hereby withdrawn. The following rejections and/or objections are either newly applied or are reiterated and are the only rejections and/or objections presently applied to the instant application. The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action. With entry of the amendment filed on 03/03/2026, claims 1-28 are pending in the application. The 102 and 103 rejections are withdrawn in response to claim amendments. The 112(b) rejection is withdrawn in response to claim amendments. Claim Rejections - 35 USC § 112 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 5 and 28 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 pre-AIA the applicant regards as the invention. Claim 5 recites wherein the engineered Cas9 protein further comprises a mutation at positions corresponding to N690, N980, or both of SpCas9. It is unclear what “both of SpCas9” means because there is only one SpCas9 protein in the dependent claim. The claim is interpreted such that the further mutation is N690 or N980 or both mutations. Claim 28 is rejected as it depends from claim 5. The following is a quotation of 35 U.S.C. 112(d): (d) REFERENCE IN DEPENDENT FORMS.—Subject to subsection (e), a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers. The following is a quotation of pre-AIA 35 U.S.C. 112, fourth paragraph: Subject to the following paragraph [i.e., the fifth paragraph of pre-AIA 35 U.S.C. 112], a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers. Claims 3, 4 and 6 are rejected under 35 U.S.C. 112(d) or pre-AIA 35 U.S.C. 112, 4th paragraph, as being of improper dependent form for failing to further limit the subject matter of the claim upon which it depends, or for failing to include all the limitations of the claim upon which it depends. Claims 3 and 4 are indefinite because they fail to further limit claim 1. Claims 3 and 4 recite the engineered Cas protein is a class 2, Type II Cas protein 1 and does not further limit claim 1 which is drawn to an engineered SpCas9 protein, which is a known class 2, Type II Cas protein. Claim 6 is rejected as being depended on a rejected claim. Claim Rejections - 35 USC § 112 The following is a quotation 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 35 U.S.C. 112 (pre-AIA ), first paragraph: 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. Written Description Claims 18-27 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 pre-AIA the inventor(s), at the time the application was filed, had possession of the claimed invention. The MPEP states that the purpose of the written description requirement is to ensure that the inventor had possession, as of the filing date of the application, of the specific subject matter later claimed by him. The courts have stated: To fulfill the written description requirement, a 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." Lockwood v. American Airlines, Inc., 107 F.3d 1565, 1572, 41 USPQ2d 1961, 1966 (Fed. Cir. 1997); In re Gostelli, 872 F.2d 1008, 1012, 10 USPQ2d 1614, 1618 (Fed. Cir. 1989) ("[T]he description must clearly allow persons of ordinary skill in the art to recognize that [the inventor] invented what is claimed."). Thus an applicant complies with the written description requirement "by describing the invention, with all its claimed limitations, not that which makes it obvious" and by using "such descriptive means as words, structures, figures, diagrams, formulas, etc., that set forth the claimed invention." Lockwood, 107 F.3d at 1572, 41 USPQ2d at 1966; Regents of the University of California v. Eli Lilly & Co., 43 USPQ2d 1398. The fundamental factual inquiry is whether the specification conveys with reasonable clarity to those skilled in the art that, as of the filing date sought, applicant was in possession of the invention as now claimed. See, e.g., Vas-Cath, Inc., 935 F.2d at 1563-64, 19 USPQ2d at 1117. The MPEP lists factors that can be used to determine if sufficient evidence of possession has been furnished in the disclosure of the application. These include: (1) Actual reduction to practice, (2) Disclosure of drawings or structural chemical formulas, (3) Sufficient relevant identifying characteristics (such as: i. Complete structure, ii. Partial Structure, iii. Physical and/or chemical properties, iv. Functional characteristics when coupled with a known or disclosed structure, and v. Correlation between function and structure), (4) Method of making the claimed invention, (5) Level of skill and knowledge in the art, and (6) Predictability in the art. Moreover, the written description requirement for a genus may be satisfied through sufficient description of a representative number of species 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 functional and structure, or by a combination of such identifying characteristics, sufficient to show the applicant was in possession of the claimed 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 claims are drawn to a genus of Cas proteins comprising at least one amino acid substitution relative to the wild-type Cas9 with the function of exhibiting a +1 insertion frequency different from the wildtype Cas9 at a target site. When determining whether the written description requirement is met for genus claims, it is first determined whether a representative number of species have been described by their complete structure. In the instant case, the specification describes a single variant Cas protein, LZ3, that exhibiting a +1 insertion frequency different from the wildtype Cas9 at a target site. This example does not encompass the vast number of different Cas proteins comprising any number of amino acid substitutions. It is then determined whether a representative number of species have been sufficiently described by other relevant identifying characteristics (i.e. other than nucleotide sequence), specific features and functional attributes that would distinguish different members of the claimed genera. In the instant case, the only other identifying characteristics are results demonstrating a variant Cas protein, LZ3, has a +1 insertion frequency different from the wild type Cas protein. The disclosure has not described any other variant Cas protein with this claimed function or describe specific amino acid sequences that would provide this function to a Cas protein. A review of the specification shows that it provides no description or guidance that would allow one of skill to distinguish the functional species of the recited structural genus from the non-functional members without empirical determination. Since the disclosure and the prior art fail to describe the common attributes and characteristics concisely identifying members of the proposed genus, and because the claimed genus is highly variant a vast number of sequences of promoters and functional fragments of a Connexin 26 protein with the function of expression in any type of inner ear support cell, one of skill in the art would reasonably conclude that the disclosure fails to provide a representative number of species to describe the genus claimed. "A sufficient description of a genus . . . requires the disclosure of either a representative number of species falling within the scope of the genus or structural features common to the members of the genus so that one of skill in the art can "visualize or recognize" the members of the genus" (AbbVie, 759 F.3d at 1297, reiterating Eli Lilly, 119 F.3d at 1568-69) (emphasis added). Further, “Possession may not be shown by merely describing how to obtain possession of members of the claimed genus or how to identify their common structural features.” Ex parte Kubin, 83 USPQ2d 1410, 1417 (Bd. Pat. App. & Int. 2007) citing University of Rochester, 358 F.3d at 927, 69 USPQ2d at 1895. Vas-Cath Inc. v. Mahurkar, 19USPQ2d 1111, clearly states that “applicant must convey with reasonable clarity to those skilled in the art that, as of the filing date sought, he or she was in possession of the invention. The invention is, for purposes of the ‘written description’ inquiry, whatever is now claimed.” (See page 1117.) 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). The MPEP further states that if a biomolecule is described only by a functional characteristic, without any disclosed correlation between function and structure of the sequence, it is “not sufficient characteristic for written description purposes, even when accompanied by a method of obtaining the claimed sequence.” MPEP 2163. The MPEP does state that for generic claim the genus can be adequately described if the disclosure presents a sufficient number of representative species that encompass the genus. MPEP 2163. If the genus has a substantial variance, the disclosure must describe a sufficient variety of species to reflect the variation within that genus. See MPEP 2163. Although the MPEP does not define what constitute a sufficient number of representative, the Courts have indicated what do not constitute a representative number species to adequately describe a broad generic. In Gosteli, the Court determined that the disclosure of two chemical compounds within a subgenus did not describe that subgenus. In re Gosteli, 872 F.2d at 1012, 10 USPQ2d at 1618. Thus the specification and claims lack written description because it is clear that Applicant did not have possession of every Cas protein comprising any number of amino acid substitutions with the claimed function. Applicant even admits that most Cas9 variants with amino acid substitutions do not exhibit altered +1 insertion frequences (see Applicant argument page 11). Applicant further states this context-dependent behavior-depending on the nucleotide identity at a specific position in the target DNA-is not an inherent property of protein structure. Altered +1 insertion frequency is not an inherent consequence of amino acid substitution but a specific functional property achieved only by particular variants (page 11). The description requirement of the patent statute requires a description of an invention, not an indication of a result that one might achieve if one made that invention. See In re Wilder, 736 F.2d 1516, 1521,222 USPQ 369,372-372 (Fed. Cir. 1984) (affirming rejection because the specification does "little more than outlin[e] goals appellants hope the claimed invention achieves and the problems the invention will hopefully ameliorate."). Accordingly, it is deemed that the specification fails to provide adequate written description for the genus of the claims and does not reasonably convey to one skilled in the relevant art that the inventors, at the time the application was filed, had possession of the entire scope of the claimed invention. Enablement The following is a quotation 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 35 U.S.C. 112 (pre-AIA ), first paragraph: 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 18-27 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, because the specification, while being enabling for methods of introducing into cells an engineered SpCas9 variant LZ3 that exhibits a +1 insertion frequence different from wildtype Cas9 at a target site and gene editing, does not reasonably provide enablement for methods of introducing into cells any engineered SpCas9 variant that exhibits a +1 insertion frequence different from wildtype Cas9 at a target site. The specification does not enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and/use the invention commensurate in scope with these claims. The following factors have been considered in the analysis of enablement: (1) the breadth of the claims, (2) the nature of the invention, (3) the state of the prior art, (4) the level of one of ordinary skill, (5) the level of predictability in the art, (6) the amount of direction provided by the inventor, (7) the existence of working examples, (8) the quantity of experimentation needed to make or use the invention based on the content of the disclosure. The breadth of the claims and the nature of the invention: The broadest reasonable interpretation of the claims are introducing into any cell an engineered Cas protein comprising any amount of amino acid substitutions wherein the Cas protein exhibits a +1 insertion frequency compare to wild type. Whether the specification would have been enabling as of the filing date involves consideration of the nature of the invention, the state of the prior art, and the level of skill in the art. The state of the prior art is what one skilled in the art would have known, at the time the application was filed, about the subject matter to which the claimed invention pertains. The relative skill of those in the art refers to the skill of those in the art in relation to the subject matter to which the claimed invention pertains at the time the application was filed. See MPEP § 2164.05(b). The state of the prior art provides evidence for the degree of predictability in the art and is related to the amount of direction or guidance needed in the specification as filed to meet the enablement requirement. The state of the prior art is also related to the need for working examples in the specification. The state of the prior art: The prior art of Bermudez-Cabrera et al. ("Small molecule inhibition of ATM kinase increases CRISPR-Cas9 1-bp insertion frequency." Nature communications 12.1 (2021): 5111) teach [m]utational outcomes following CRISPR-Cas9-nuclease cutting in mammalian cells have recently been shown to be predictable and, in certain cases, skewed toward single genotypes. However, the ability to control these outcomes remains limited, especially for 1-bp insertions, a common and therapeutically relevant class of repair outcomes. The ability to increase CRISPR-Cas9 1-bp insertion outcomes promises to improve precision genome editing applications. For instance, biasing outcomes toward 1-bp insertions will enable reliably increased CRISPR-Cas9 knockout efficiency given that MH deletions are more likely to retain frame. Thus, while the state of the art recognized the advantages of increasing 1-bp insert frequency in CRISPR systems, it does not teach variant Cas proteins with any amino acid substitutions will exhibit a +1 insertion frequency that is different than the wild-type. The level of one of ordinary skill: While the level of one of ordinary skill practicing said invention would be high, the level of predictability is considered variable as evident in the prior art discussed above and is not considered to provide sufficient enablement to practice the claimed invention. Because the state of the prior art does not provide evidence of the degree of predictability that engineered Cas proteins exhibits a +1 insertion frequency when modified with at least one amino acid, one of ordinary skill in the art would look for guidance or direction in the instant specification. The level of predictability in the art: “The “predictability or lack thereof” in the art refers to the ability of one skilled in the art to extrapolate the disclosed or known results to the claimed invention. If one skilled in the art can readily anticipate the effect of a change within the subject matter to which the claimed invention pertains, then there is predictability in the art. On the other hand, if one skilled in the art cannot readily anticipate the effect of a change within the subject matter to which that claimed invention pertains, then there is lack of predictability in the art. Accordingly, what is known in the art provides evidence as to the question of predictability.” (MPEP 2164.03). The amount of direction provided by the inventor: The amount of guidance or direction needed to enable the invention is inversely related to the amount of knowledge in the state of the art as well as the predictability in the art. In re Fisher, 427 F.2d 833, 839, 166 USPQ 18, 24 (CCPA 1970). The “amount of guidance or direction” refers to that information in the application, as originally filed, that teaches exactly how to make or use the invention. The more that is known in the prior art about the nature of the invention, how to make, and how to use the invention, and the more predictable the art is, the less information needs to be explicitly stated in the specification. In contrast, if little is known in the prior art about the nature of the invention and the art is unpredictable, the specification would need more detail as to how to make and use the invention in order to be enabling. >See, e.g., Chiron Corp. v. Genentech Inc., 363 F.3d 1247, 1254, 70 USPQ2d 1321, 1326 (Fed. Cir. 2004). The existence of working examples: Applicants demonstrated that a variant LZ3 Cas9 had a +1 insertion frequency different from a WT SpCas9. The working embodiments do not describe any other variant Cas9 with this function or provide evidence that any Cas protein with at least one amino acid substitution would have +1 insertion frequency different from a WT SpCas9. Applicant even admits that most Cas9 variants with amino acid substitutions do not exhibit altered +1 insertion frequences (see Applicant argument page 11). Applicant further states this context-dependent behavior-depending on the nucleotide identity at a specific position in the target DNA-is not an inherent property of protein structure. Altered +1 insertion frequency is not an inherent consequence of amino acid substitution but a specific functional property achieved only by particular variants (page 11). The standard of an enabling disclosure is not the ability to make and test if the invention works but one of the ability to make and use with a reasonable expectation of success. A patent is granted for a completed invention, not the general suggestion of an idea (MPEP 2164.03 and Chiron Corp. v. Genentech Inc., 363 F.3d 1247, 1254, 70 USPQ2d 1321, 1325-26 (Fed. Cir. 2004). While the MPEP 2164.02 states the specification need not contain an example if the invention is otherwise disclosed in such manner that one skilled in the art will be able to practice it without an undue amount of experimentation. In re Borkowski, 422 F.2d 904, 908, 164 USPQ 642, 645 (CCPA 1970), the lack of a working example, however, is a factor to be considered, especially in a case involving an unpredictable and undeveloped art. The quantity of experimentation needed to make or use the invention based on the content of the disclosure: The prior art is unpredictable for the role any amino acid substitution of a Cas9 protein would play in increasing the insertion frequency in a CRISPR system. Without further guidance, one of skill in the art would have to practice a substantial amount of trial and error experimentation, an amount considered undue and not routine, to practice the instantly claimed invention. Closest Prior Art and Reasons for Allowability Claims 1, 2, 7-17 and 28 are allowable. The closest prior art of Vakulskas et al. (of record), teach a composition comprising an engineered Cas protein that comprises a RuvC domain and a HNH domain (para [0003] - [0011]) and teach the sequence of SpCas9 mutant N960 and encoded polypeptide (SEQ ID No. 150) which has 99.7% similarity to instantly claimed SEQ ID No. 1300. Sternberg et al. (of record) teach the CRISPR-Ca9 system comprises a linker domain that connects the RuvC domain and the HNH domain wherein the linkers and domains are mutated to reduce cleavage (see 0007). Sternberg et al. teach a spCas9 can comprise mutations such as G915 (0057). Liu et al. (of record) teach spCas9 variants comprising mutations at position T769 and teach these Cas9 variants provide a solution to the off-target/fidelity problems associated with native and current Cas9 variants (0008). The prior art in combination does not teach or make obvious an engineered Cas Protein having mutations T769 and G915 or T69, G915, N609 and N980. While the prior art teach each of the mutations can be made in Cas9, the prior art does not provide a motivation to pick and choose the combination of mutations to create an engineered Cas protein as claimed. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to Kimberly Chong at (571)272-3111. The examiner can normally be reached Monday thru Friday between M-F 8:00am-4:30pm. If attempts to reach the examiner by telephone are unsuccessful please contact the SPE for 1636 Neil Hammell at 571-272-5919. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Patent applicants with problems or questions regarding electronic images that can be viewed in the Patent Application Information Retrieval system (PAIR) can now contact the USPTO’s Patent Electronic Business Center (Patent EBC) for assistance. Representatives are available to answer your questions daily from 6 am to midnight (EST). The toll free number is (866) 217-9197. When calling please have your application serial or patent number, the type of document you are having an image problem with, the number of pages and the specific nature of the problem. The Patent Electronic Business Center will notify applicants of the resolution of the problem within 5-7 business days. Applicants can also check PAIR to confirm that the problem has been corrected. The USPTO’s Patent Electronic Business Center is a complete service center supporting all patent business on the Internet. The USPTO’s PAIR system provides Internet-based access to patent application status and history information. It also enables applicants to view the scanned images of their own application file folder(s) as well as general patent information available to the public. For more information about the PAIR system, see http://pair-direct.uspto.gov. For all other customer support, please call the USPTO Call Center (UCC) at 800-786-9199. /KIMBERLY CHONG/ Primary Examiner Art Unit 1636
Read full office action

Prosecution Timeline

Sep 09, 2022
Application Filed
Mar 05, 2024
Response after Non-Final Action
May 23, 2025
Non-Final Rejection mailed — §112
Aug 22, 2025
Response Filed
Dec 08, 2025
Final Rejection mailed — §112
Mar 03, 2026
Request for Continued Examination
Mar 09, 2026
Response after Non-Final Action
Jul 08, 2026
Non-Final Rejection mailed — §112 (current)

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Prosecution Projections

3-4
Expected OA Rounds
72%
Grant Probability
85%
With Interview (+12.6%)
2y 6m (~0m remaining)
Median Time to Grant
High
PTA Risk
Based on 1488 resolved cases by this examiner. Grant probability derived from career allowance rate.

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