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 .
Claim Status
Receipt is acknowledged of the preliminary amendments filed on 16 February, 2024. Claims 1-57 are cancelled. Claims 58-77 are newly added.
Therefore, claims 58-77 are pending and under examination in the present Official Action.
Priority
The present application is a 35 U.S.C. 371 national stage filing of International Application No. PCT/IB2021/062018, filed 20 December, 2021, which claims priority to United States Provisional Application Nos. 63212457, filed 18 June, 2021, and 63129934, filed 23 December, 2020. Acknowledgment is made of applicant’s claim for priority.
The earliest possible priority for the instant application is 23 December, 2020.
Drawings
The drawings submitted on 04 June, 2023 are accepted by the Examiner.
Specification
The use of the term “CaptureSelect”, which is a trade name or a mark used in commerce, has been noted in this application. The term should be accompanied by the generic terminology; furthermore the term should be capitalized wherever it appears or, where appropriate, include a proper symbol indicating use in commerce such as ™, SM , or ® following the term.
Although the use of trade names and marks used in commerce (i.e., trademarks, service marks, certification marks, and collective marks) are permissible in patent applications, the proprietary nature of the marks should be respected and every effort made to prevent their use in any manner which might adversely affect their validity as commercial marks.
Claim Objections
Claim 58 is objected to because of the following informalities: “pH” in the third line is missing a definite article (for example “a”). Appropriate correction is required.
Claim 60 is objected to because of the following informalities: the sentence is grammatically incorrect for not modifying “said buffering agent”. The use of “which” insinuates multiple modifications but the claim sets forth only one. It is suggested to remove “which” from the claim. Appropriate correction is required.
Claim 64 is objected to because of the following informalities: the sentence is grammatically incorrect in its recitation of “is or”. Appropriate correction is required.
Claim 70 is objected to because of the following informalities: claim 70 should recite a distinct article (either “a” or “the”) for each of the first and second regeneration buffers to be grammatically correct. Appropriate correction is required.
Claim 77 is objected to because of the following informalities: claim 77 recites “AAV capsids consisting of” followed by a list of AAV serotypes. The list is a list of viruses, not capsids. It is recommended to amend claim 77 to recite “…comprises an AAV capsid of an AAV selected from the group consisting of…”. Appropriate correction is required.
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 70 and 75 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.
Claim 70 recites the limitation "said first or second regeneration buffer" in the second line of the claim. There is insufficient antecedent basis for this limitation in the claim. Claim 66 from which claim 70 depends recites a first regeneration buffer but nowhere in claim 66 or claim 58 from which claim 70 ultimately depends is there a recitation of a second regeneration buffer. Were claim 70 to be amended to depend from claim 68 instead, this would overcome the antecedent basis issue. However, it is noted that claim 70 should recite a distinct article (either “a” or “the”) for each of the first and second regeneration buffers to be grammatically correct (see claim objection above).
Claim 75 is rejected for being indefinite because it is unclear what Applicant intends to encompass with the recitation of “at least 4 purification cycles”. Claim 75 depends directly from claim 58 which does not recite “purification cycles”. Thus, there is insufficient antecedent basis for “purification cycles”. Further, it is unclear whether a purification cycle is intended to encompass running elution buffer or successive loading of rAAV and running of elution buffer. The plain language of claim 58 only requires elution, but the recitation of “purification cycles” implies more than just elution. Thus, the scope of claim 75 is unclear and a person having ordinary skill in the art would not be apprised of the scope of the patent protection sought.
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 58-77 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 a method of purifying a recombinant AAV9 (rAAV9) vector, comprising: a step of loading an affinity chromatography stationary phase with a solution containing an rAAV9 vector, and a step of contacting the affinity chromatography stationary phase to which is bound a rAAV9 vector with an elution buffer under conditions which allow the elution buffer to flow through the affinity chromatography stationary phase, producing an affinity eluate, wherein said elution buffer comprises between 25 and 200 mM magnesium chloride and has a pH less than 5, and wherein the affinity chromatography stationary phase is a resin comprising 50 μm porous polystyrenedivinylbenzene beads modified with a camelid-derived single domain antibody ligand which has affinity for AAV9, does not reasonably provide enablement for a method of purifying any rAAV comprising only a single step of contacting any affinity chromatography stationary phase with any elution buffer comprising any amount of magnesium chloride with a pH less than 5. The specification does not enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to use the invention commensurate in scope with these claims.
The test of enablement is whether one skilled in the art could make and use the claimed invention from the disclosures in the patent coupled with information known in the art without undue experimentation (United States v. Telectronics, Inc., 8 USPQ2d 1217 (Fed. Cir. 1988)). Whether undue experimentation is required is not based on a single factor but is rather a conclusion reached by weighing many factors (See Ex parte Forman, 230 USPQ 546 (Bd. Pat. App. & Inter, 1986) and In re Wands, 8USPQ2d 1400 (Fed. Cir. 1988); these factors include the following:
1) Nature of invention. The instant claims are drawn to method of purifying an rAAV comprising only a step of elution with an elution buffer which comprises magnesium chloride and which has a pH less than 5.
2) Scope of the invention. The scope of the invention is broad insofar as it requires a method of purifying an rAAV comprising only a step of eluting. The method does not detail the steps for the rAAV to be loaded onto the column, nor does it require the elution buffer to flow through the affinity chromatography stationary phase to produce the affinity eluate. Thus, the claims are directed to a broad genus of methods which encompass merely pouring any elution buffer with any amount of magnesium and a pH of less than 5 onto a stationary phase to purify the rAAV. Further, the claims are broad insofar as they encompass a genus of methods for purifying any rAAV with the use of any affinity chromatography stationary phase. At its broadest this encompasses a method of purifying at least any or all of the AAV serotypes listed in claim 77 with any affinity chromatography stationary phase (including stationary phases which are designed for binding to targets other than AAVs like those with immobilized hormone receptors or those with Protein A/G resins for binding to antibody Fc regions).
3) Number of working examples and guidance. The specification teaches the production of rAAV9 vectors in HEK293T cells followed by lysis of those cells to release full AAV9 capsids with genomes, intermediate capsids and empty capsids ([0266]). The specification then teaches filtering the lysis solution through a 0.2μm filter to produce a clarified lysate ([0266]). This clarified lysate was then loaded onto a POROSTM CaptureSelectTM AAV9 column, followed by a pre-elution wash of the column with various solutions, followed by elution in a solution containing 150mM sodium acetate, 25 mM MgCl2, and 100mM glycine at a pH of 3 (Table 1). Example 2 describes the screening of magnesium chloride concentrations up to 200mM and pH level for the elution buffer. The purification protocol for example 2 was the same as for example 1 with the exception of the elution buffer (Table 4). The specification teaches that there is an optimal conductivity range for the elution buffer (20-34 mS/cm) which prevented co-elution of residual impurities and that the most favorable condition was a lower magnesium chloride concentration along with a pH of 3 ([0274]-[0275]). Example 3 uses the same general purification protocol as examples 1 and 2 with rAAV9 vector production, loading, pre-elution wash, then elution using the same CaptureSelectTM AAV9 column ([0276]-[0277], Table 7). Example 3 differs by varying elution buffer to determine its effect on downstream anion exchange chromatography. Example 4 describes the anion exchange chromatography ([0286]). The specification also teaches scale up studies which used different elution buffers, one with 30mM citrate, 100mM glycine, 100mM magnesium chloride at pH 3 and one with 150mM acetate, 100mM glycine, 100mM magnesium chloride at pH 3 (Table 17, [0301]). None of the remaining examples, and none of the examples herein discussed, teach anything other than rAAV9 vectors loaded onto and eluted from POROSTM CaptureSelectTM AAV9 columns. The specification teaches that POROSTM CaptureSelectTM AAV9 affinity resins are comprised of 50 μm porous polystyrenedivinylbenzene beads modified with a Camelid-derived single domain antibody ligand ([0039]).
4) State of the art. The use of CaptureSelectTM columns which bind AAV9 for the specific capture of AAV9 particles is well explored in the art (WO2019/133677, hereinafter “Fieldler”, and Florea, et al. Molecular Therapy Methods & Clinical Development 28 (2023): 146-159. Hereinafter “Florea”). Fieldler teaches the purification of AAV9 particles using a POROSTM CaptureSelectTM AAV9 affinity resin (Fieldler, [00235]), and teaches an elution buffer comprised of 50mM TrisHCl, 50% ethylene glycol and 750mM-2000mM NaCl at pH 8 or an elution buffer comprised of 100mM sodium citrate at pH 3 (Fieldler, [00237], Table 15). Florea teaches that currently available affinity resins for AAV purification include specific resins (CaptureSelect specific for AAV9) and an AAVX resin which is marketed as a pan-AAV affinity resin (Florea, page 147, first partial paragraph). Florea teaches that to-date (in this case 2023 which is after the filing date of the instant invention) there are no independently generated published data on assessing the performance of AAVX (Id.). With regard to AAV purification more generally, Smith teaches that AVB resins bind to AAV1, AAV2, and AAV5 but not to AAV8 or AAV9 while the CaptureSelect AAV8 resin binds to AAV1 and AAV9 and the CaptureSelect AAV9 resin only binds to AAV9 (Mietzsch, et al. Molecular Therapy Methods & Clinical Development 19 (2020): 362-373. Hereinafter “Smith”, Figure 2). Thus, at the time of filing, the state of the art for AAV purification was specific depending on the serotype being purified and employed only CaptureSelect AAV9 to purify AAV9 particles.
5) Unpredictability of the art. The art of pan-specific affinity chromatography for AAV lacked adequate enablement at the time of the instant invention. The affinity matrix as well as solution conditions are specific per AAV serotype. Fieldler specifically teaches the use of an AAV9-specific CaptureSelectTM affinity matrix to purify AAV9 with an elution buffer comprised of 50mM TrisHCl, 50% ethylene glycol and 750mM-2000mM NaCl at pH 8 or an elution buffer comprised of 100mM sodium citrate at pH 3 (Fieldler, [00237], Table 15). Fieldler also suggests that magnesium chloride and an acidic buffer can be used to elute AAV9 from CaptureSelect columns (Fieldler, Table 42). Fieldler also discusses AAV8 purified with the AAV8 variant CaptureSelect resins, however Fieldler is silent as to the purification of any other AAV serotypes using CaptureSelect or any other affinity resins (there is discussion of AAVX but no legible evaluation of AAVX) (Fieldler, Table 43, [00366]). Smith teaches that even small changes to AAV9 capsids can abrogate binding to CaptureSelect affinity resins (Mietzsch, et al. Molecular Therapy Methods & Clinical Development 19 (2020): 362-373. Hereinafter “Smith”, Abstract, page 369, first full paragraph). Smith teaches that AAV8-specific CaptureSelect resins are capable of binding AAV1 and AAV8 while AAV9-specific CaptureSelect Resins only bind AAV9 (Smith, Figure 2). Smith also teaches that a change in as little as two amino acids in the capsid of AAV8 significantly reduced binding to the AAV8-specific resin (Smith, page 369, first full paragraph, Figure 4). Thus, there is unpredictability of the ability of any given affinity chromatography stationary phase to bind to and facilitate purification of any given AAV because affinity chromatography stationary phases are AAV serotype-specific. Further, even in the case of a specific affinity chromatography stationary phase and its cognate AAV serotype, purification is unpredictable because even small changes to the AAV capsid can abrogate binding to the stationary phase. Even further, variation exists in the art with respect to elution buffers used to elute AAV particles from affinity resins (See above Fieldler discussion).
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 M.P.E.P. § 2164.03.
As well, the claims are drawn to an incredibly large genus of methods of purification and AAV vectors. In cases involving predictable factors, such as mechanical or electrical elements, a single embodiment provides broad enablement in the sense that, once imagined, other embodiments can be made without difficulty and their performance characteristics predicted by resort to known scientific laws. In cases involving unpredictable factors, such as most chemical reactions and biological activity, the scope of enablement varies inversely with the degree of unpredictability of the factors involved. The claims broadly require “purifying” with the sole step of eluting being positively recited and the claims broadly require any affinity chromatography stationary phase and any elution buffer having magnesium chloride and a pH less than 5 for accomplishing the purifying of any AAV. The degree of unpredictability evidenced by the art at the time of filing with respect to affinity chromatography stationary phases, AAV serotypes, and elution buffers leads to a relatively narrow scope of enablement when the only examples provided in the instant Application are with AAV9, CaptureSelect AAV9 resins, and
This raises issues under description as well as enablement. The description component of the rejection is herein included as you cannot use what you have not described. Furthermore, the enablement of the instant invention has been assessed in light of the specification and the prior art available at the time of filing. "However, claims reading on significant numbers of inoperative embodiments would render claims non-enabled when the specification does not clearly identify the operative embodiments and undue experimentation is involved in determining those that are operative. Atlas Powder Co. v. E.I. duPont de Nemours & Co., 750 F.2d 1569, 1577, 224 USPQ 409, 414 (Fed. Cir. 1984); In re Cook, 439 F.2d 730, 735, 169 USPQ 298,302 (CCPA 1971). (see MPEP 2164.08(b). Specifically, the method of purifying is more limited than by any as claimed as set forth above. The genus of methods claimed encompasses a significant number of inoperative embodiments insofar as it encompasses purifying any rAAV with any affinity chromatography stationary phase (including a vast selection of stationary phases which have nothing to do with AAV purification) comprising only a step of contacting the stationary phase with an elution buffer. The genus claimed does not even require the loading of the stationary phase with rAAV particles or the elution buffer to flow through the stationary phase. Even further, the function of “purifying” isn’t claimed with any structures other than the single step of contacting with an elution buffer. Thus, there is insufficient structure-function between the broad genus claimed and the function claimed. At a minimum, the specification teaches that rAAV needs to be loaded onto the affinity chromatography stationary phase, washed, then eluted by contacting the stationary with an elution buffer under conditions which allow the elution buffer to flow through the affinity chromatography stationary phase, producing an affinity eluate.
6) Amount of Experimentation Required. The claims have been evaluated in light of the art at the time of filing and found not to be commensurate in scope with the specification. MPEP 2164.05 teaches, “However, the examiner should carefully compare the steps, materials, and conditions used in the experiments of the declaration with those disclosed in the application to make sure that they are commensurate in scope; i.e., that the experiments used the guidance in the specification as filed and what was well known to one of skill in the art. Such a showing also must be commensurate with the scope of the claimed invention, i.e., must bear a reasonable correlation to the scope of the claimed invention.
Consequently, the prior art (and post-filing art) when combined with the lack of any disclosed experimental test of methods of purification other than the one disclosed for rAAV9, shows that one of skill in the art at the time the invention was made would have had no basis to reasonably predict or conclude the claimed methods of purifying could be identified given the lack of details necessary to identify those meeting the necessary functions for all possible combinations of affinity chromatography stationary phases and AAV serotypes. Though not controlling, the lack of working examples, is, nevertheless, a factor to be considered. When a patent applicant chooses to forego exemplification and bases utility on broad terminology and general allegations, he runs the risk that unless one with ordinary skill in the art would accept the allegations as obviously valid and correct, the PTO may, properly, ask for evidence to substantiate them. Ex parte Sudilovsky, 21 USPQ2d 1702, 1705 (BPAI 1991); In re Novak, 134 USPA 335 (CCPA 1962); In re Fouche, 169 USPQ 429 (CCPA 1971).
Given the very specific pairings and purification conditions taught in the art relative to the very broad methods that are claimed, the level of unpredictability embodied in the species encompassed by the genus claimed, and the amount of experimentation required to determine the operable species, it would require undue experimentation to use the invention commensurate in scope with the claims. Further, in an unpredictable art, the disclosure of limited examples (requiring more steps than just “contacting” with an elution buffer and utilizing only AAV9 purified on an AAV9-specific resin) would represent to the skilled artisan that applicants were not in possession of claimed genus.
Discussion of relevant art
The closest prior art to the instant invention is Fieldler (applied above in the 112(a) rejection). Fieldler discloses methods for the purification of AAV using an affinity resin (Fieldler, Abstract). Fieldler teaches the use of an AAV9-specific CaptureSelectTM affinity matrix to purify AAV9 with an elution buffer comprised of 50mM TrisHCl, 50% ethylene glycol and 750mM-2000mM NaCl at pH 8 or an elution buffer comprised of 100mM sodium citrate at pH 3 (Fieldler, [00237], Table 15). Fieldler suggests that magnesium chloride and an acidic buffer can be used to elute AAV9 from CaptureSelect columns (Fieldler, Table 42). Fieldler teaches that the AAV9 is a recombinant AAV9 (Fieldler, [00173]). Fieldler claims a method of purifying an AAV comprising loading an AAV containing solution onto an affinity resin targeted against AAV under conditions that allow binding between the AAV in the solution and the affinity resin; undertaking at least two wash steps; and eluting the AAV from the affinity resin (Fieldler, claim 1). Fieldler teaches that the elution was done by applying elution buffer to the column at a linear flow rate of 60 cm/h (Fieldler, [00198]-[00199]).
The identified claim scope does not appear to be prima facie obvious over Fieldler. Even though Fieldler suggests to add magnesium chloride to the elution buffer, Fieldler stops short of a specific teaching, or suggestion to use an elution buffer having 25-200mM magnesium chloride and a pH less than 5.
Conclusion
No claim is allowed.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to BRENDAN THOMAS TINSLEY whose telephone number is (703)756-5906. The examiner can normally be reached Mon-Fri 8:00-5:00.
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, MARIA G LEAVITT can be reached at 571-272-1085. 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.
/BRENDAN THOMAS TINSLEY/Examiner, Art Unit 1634
/MARIA MARVICH/Primary Examiner, Art Unit 1634