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
Claims 1-4, 8-10, 14-16, 21, 24, 26, 32, 34, 44-45, 55-56, and 61 are pending and under examination on their merits. Claims 5-7, 11-13, 17-20, 22-23, 25, 27-31, 33, 35-43, 46-54, 57-60, and 62-88 are cancelled.
Claim Objections
Claim 61 is objected to because of the following informalities: the acronym should be spelled out as Tay-Sachs disease (TSD) or Sandhoff disease (SD).
Appropriate correction is required.
Drawings
The drawings are objected to because Fig. 7, 9A, 9C, 9D, 9G, 11A-C and 13A are low resolution and in grayscale. The grayscale renderings of color images are not comprehensible (the significance of the legends is lost). Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
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 1-4, 8-10, 14-16, 21, 24, 26, 32, 34, 44-45, 55-56, and 61 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 1 recites a recombinant β-hexosaminidase variant α subunit that forms a β-hexosaminidase variant α subunit homodimer. The claim is subject to at least three different reasonable interpretations. In one interpretation, the claim is drawn to the subunit (protein fragment). In a second interpretation, the claim is drawn to the homodimer. In a third interpretation, the claim is drawn to a variant of a homodimer of SEQ ID NO: 6. Claim 1 is further indefinite because it is unclear whether the claim requires the recombinant β-hexosaminidase variant α subunit sequence to comprise any portion of SEQ ID NO: 1. It is further unclear whether additional amino acid substitutions are permissible at positions other than those recited in the claim or those that increase cellular uptake. Still further unclear is whether the homodimer further comprises the one or more amino acid sequence elements that increase cellular uptake of the homodimer or whether the subunit further comprises the one or more amino acid sequence elements. Under the first interpretation, an α/α homodimer with a single cellular targeting domain appended to the homodimer is within the scope of the claim. Under the second interpretation, the sequence element is a feature of the α subunit, so the homodimer necessarily contains twice the number of sequence elements. Claim 1 is further indefinite for “a homodimer of SEQ ID NO: 1” because it is unclear whether SEQ ID NO: 1 is the sequence of the homodimer or the sequence of the β-hexosaminidase variant α subunit that forms the homodimer.
Claims 2-4, 8-10, 14-16, 21, 24, 26, 32, 34, 44-45, 55-56, and 61 are rejected for depending from a rejected base claim and not rectifying the source of indefiniteness discussed above.
Claim 32 recites an indefinite limitation, wherein the b-hexosaminidase variant a subunit comprises at least 550 contiguous amino acids of an amino acid sequence according to SEQ ID NO: 3, and at least 95% sequence identity to the at least 550 contiguous amino acids. It is uncertain whether claim 32 requires a protein sequence comprising at least 550 contiguous amino acids of SEQ ID NO: 3 (narrow limitation), and at least 95% sequence identity to the at least 550 contiguous amino acids (broad limitation) in the same claim, or claim 32 requires a first amino acid sequence comprising at least 550 contiguous amino acids of SEQ ID NO: 3, and a second amino acid sequence.
Claim 34 is further indefinite because the claim recites the beta-hexosaminidase variant alpha subunit homodimer comprises an increased mannose-6-phosphorylation (M6P) relative to a homodimer of SEQ ID NO: 6. There are at least two different reasonable interpretations for this limitation in the claim, rendering the claim indefinite. In one interpretation, the increased mannose-6-phosphorylation refers to the total mannose-6-phorphorylation of the entire homodimer relative to a homodimer of SEQ ID NO: 6. In a second interpretation, the increased mannose-6-phosphorylation refers to increased M6P at any position relative to a homodimer of SEQ ID NO: 6.
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 1-4, 8-10, 14-16, 21, 24, 32, 34, 44-45, 55-56, and 61 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 claims contain 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 inventors, at the time the application was filed, had possession of the claimed invention.
Claim 1 recites a recombinant β-hexosaminidase variant α subunit that forms a β-hexosaminidase variant α subunit homodimer comprising one or more amino acid sequence elements that increase cellular uptake of the β-hexosaminidase variant α subunit homodimer relative to a homodimer of SEQ ID NO: 6.
Claim 1 is interpreted as being drawn to the β-hexosaminidase α subunit comprising SEQ ID NO: 1 with the recited amino acid substitutions, wherein the subunit further comprises one or more sequence elements that increase cellular uptake relative to SEQ ID NO: 6, and wherein the subunit is capable of forming a homodimer.
The person of ordinary skill in the art would not have recognized that the inventors had possession of the claimed genus of β-hexosaminidase variant α subunits capable of forming a homodimer with sequence elements that increase cellular uptake of the homodimer relative to SEQ ID NO: 6.
Claim 1 recites a broad genus in which the sequence elements are unlimited in structure except for the functional limitation that they increase cellular uptake of the homodimer relative to SEQ ID NO: 6. Claim 2 limits the sequence elements to amino acid sequence substitutions, additions, or deletions relative to SEQ ID NO: 1.
The specification discloses a single species of the claimed genus. Namely, HexD3, which is SEQ ID NO: 3 (561 amino acids). SEQ ID NO: 3 contains SEQ ID NO: 13 (197 amino acids) N-terminal to SEQ ID NO: 11 (339 amino acids), with some intervening amino acids (see OA Appendix C, which shows the alignment of SEQ ID NO: 13 to SEQ ID NO: 3 and OA Appendix D, which shows the alignment of SEQ ID NO: 11 to SEQ ID NO: 3).
The specification discloses that HexD3 is a hybrid comprising sequences taken from both the α and β subunits of β-hexosaminidase ([0237]). HexD3 contains the signal sequence and amino terminal sequences of the β-subunit ([0237]), which contains consensus glycosylation sites that increase the number of M6P groups on the variant enzyme ([0237] and Fig. 1B). The specification discloses that replacing domain 1 on the HexM α subunit scaffold with the β-subunit domain 1 results in an increased M6P type N-glycan content ([0238]). HexM is a homodimeric variant hexosaminidase of the α subunit S184K, P209Q, N228S, P229Δ, V230L, T231S, P429Q, K432R, D433K, I436K, N466A, S491R, L493M, T494D, F495D, E498D, L508V, Q513V, N518Y, V519A, F521Y, and E523N of the native β-hexosaminidase a subunit sequence ([0239]).
The specification discloses that HexD3 has increased cellular uptake relative to HexM ([0267]; Fig. 3A and 3B). Table 16 on page 65 illustrates the differences between HexA, HexM, and HexD3. The specification discloses that HexD3 has increased M6P type N-glycan content compared with HexM and HexA ([0238]). HexD3, HexM, and HexA have different N-glycan profiles ([0241] and Fig. 16).
The specification does not disclose any species of recombinant β-hexosaminidase variant α subunit that forms a homodimer in which the α subunit comprises any of the mutations recited in claim 1 and wherein the variant subunit further comprises a sequence element that is an amino acid substitution or deletion that increases cellular uptake of the homodimer relative to SEQ ID NO: 6.
Mahuran (US 2015/0258180 A1) teaches a recombinant β-hexosaminidase variant subunit, wherein the variant forms a homodimer (Mahuran claim 1). The amino acid sequence of the variant comprises a deletion at position 229 of SEQ ID NO: 1 (Mahuran claim 6) or amino acid substitutions S184K, P209Q, N228S, V230L, T231S, P429Q, K432R, D433K, I436K, N466A, S491R, L493M, T494D, F495D, E498D, L508V, Q513A, N518Y, V519A, F521Y and E523N corresponding to the amino acid numbering set forth in SEQ ID NO: 1 ([0008]). SEQ ID NO: 1 of Mahuran is identical to the instant SEQ ID NO: 1 (OA Appendix A). Mahuran teaches the β-hexosaminidase variant SEQ ID NO: 2 (Fig. 1), which is identical to the instant SEQ ID NO: 6 (OA Appendix B). Mahuran also teaches the structure-function correlation for specific residues within the α subunit of β-hexosaminidase in terms of both activity and dimerization (see Table 3 and Table 4).
Tropak et al. (Molecular therapy Methods & clinical development 3 (2016)) teaches that beta-hexosaminidase exists as HexA (α/β heterodimer), HexB (β/β homodimer), or HexS (α/α), although HexS is detectable at very low levels because it is unstable (page 15056, Introduction, left column, paragraph 2). While each subunit (α and β) contains its own active site, residues from the neighboring subunit must stabilize the subunit in order for it to become functional (page 15056, Introduction, left column, paragraph 2). Tropak teaches that the α and β subunits have different substrate specificities due to a positively charged binding pocket in the α subunit, which is negatively charged in the β subunit (page 15056, right column, paragraph 1). Tropak teaches that most soluble lysosomal enzymes, including Hex, depend on their Asn-linked oligosaccharides being specifically tagged in the ER/Golgi with mannose-6-phosphate residues (M6P) to both target them to lysosomes and allow their secreted forms to be recaptured by other cells (page 15058, right column, bottom paragraph). Tropak teaches that HexM contains M6P residues (the presence of M6P in the growth medium of cells blocks endocytosis of HexM: see Table 2 on page 15058 and left column, top paragraph on page 15057, through right column on page 15057).
Čaval et al. (Molecular & Cellular Proteomics 18.1 (2019): 16-27) teaches that position 157 of the β-hexosaminidase α subunit has a M6P modification (Table 1). Čaval teaches that the M6P biosynthetic pathway is complex (see Fig. 1) and begins with co-translational modification in the rough endoplasmic reticulum that results in the N-glycosidic linkage of a 1,4-sugar glycan entity on selected asparagine residues in targeted proteins (page 16, right column, middle of full paragraph). Sonderfeld-Fresko, et al. (Journal of Biological Chemistry 264.13 (1989): 7692-7697) teaches that the mannose oligosaccharides are added to the selected Asn residues in the context of the sequence Asn-X-Ser/Thr (page 7692, left column, top paragraph). Asparagine residues at positions 84, 142, 190, 327, and 497 in the beta-chain occur in the recognition sequence for N-linked glycosylation (Sonderfeld-Fresko page 7693, left column, Results, paragraph 1).
Matsuoka (Molecular Therapy 18.8 (2010): 1519-1526) teaches amino acid substitutions S51N and A53T in the α-subunit of β-hexosaminidase A increase cellular uptake of the HexA mutant relative to wild-type HexA (Abstract). Matsuoka teaches amino acid substitutions S51N and A53T in the α-subunit of β-hexosaminidase A increase cellular uptake of the HexA mutant relative to wild-type HexA (Abstract). Matsuoka teaches that these amino acid substitutions result in an additional mannose-6-phosphate (M6P)-type N-glycan, which is recognized by the cellular M6P-receptor (Abstract; Introduction, paragraph bridging left and right columns on page 1519). Thus, the prior art teaches two amino acid substitutions with the function of increased cellular uptake of the HexA mutant.
The prior art of LeBowitz et al. (US 20120141452 A1) teaches a lysosomal enzyme such as β-hexosaminidase A (α/β heterodimer) or B (β/β subunit homodimer) and a lysosomal targeting domain that binds human cation independent mannose-6-phosphate receptor in a mannose-6-phosphate-independent manner; wherein the lysosomal targeting domain comprises a mutein of mature human IGF-II having an amino acid sequence at least 70% identical to mature human IGF-II (SEQ ID NO: 8). However, LeBowitz does not teach a homodimer of the α subunit, wherein each α subunit is modified with sequence elements that increase cellular uptake of the homodimer relative to SEQ ID NO: 6.
To summarize, although the structure-function correlation for dimerization of HexM, which is a mutant of the α subunit of β-hexosaminidase, is taught by the prior art, the structure-function correlation for HexM fusion proteins is not taught by the prior art. The addition of amino acids to the variant α subunit would have had an unpredictable effect on the tertiary structure of the protein subunits and the dimerization reaction. Tiana et al. (Proteins: Structure, Function, and Bioinformatics 49.1 (2002): 82-94) teaches that dimerization can occur by at least two different mechanisms: in one mechanism, the denatured chains assume conformations rich in native structures independently of each other and subsequently the two parts come together to form the dimer (page 82, Introduction, left column, paragraph 1), whereas in the second mechanism, chains dimerize without populating any monomeric native-like intermediate through a two-state process (page 82, Introduction, left column, paragraph 1). The addition of amino acids has unpredictable effects on the mechanism of dimerization. For example, additional amino acids can influence the stability of monomeric intermediates by inducing misfolding or the additional amino acids can lead to steric hindrance of the dimerization interface.
Although claims 9-10 and 14 limit the structure of the first amino acid sequence of the α subunit, the second amino acid sequence is unlimited except for the functional requirement that the sequence must increase cellular uptake of the homodimer. However, there is an insufficient number of species disclosed within the specification and an absence of such species in the prior art. The claim has two different functional limitations: (1) the subunit is capable of forming a homodimer, and (2) the homodimer has increased cellular uptake relative to SEQ ID NO: 6. There is no established structure-function correlation between both functions and the structure of the claimed variant subunit.
Claim 15 requires that the second amino acid sequence comprises at least 20 contiguous amino acid residues of SEQ ID NO: 2 (the β subunit of β-hexosaminidase). However, only the single species of second amino acid sequence (SEQ ID NO: 13) is disclosed within the working examples of the specification. SEQ ID NO: 13 is 197 amino acids long and there is no known structure-function relationship between the second sequence and the combined functions of both dimerization and cellular entry.
Regarding claim 16, amino acid residues 1-155 of SEQ ID NO: 12 are identical to residues 43-197 of SEQ ID NO; 13. Thus, SEQ ID NO: 12 is a smaller fragment of SEQ ID NO: 13. However, again, there is no known structure-function correlation between the second amino acid sequence and the combined functions of both dimerization and cellular entry.
Claim 21 recites the second amino acid sequence comprises at least 95% sequence identity to SEQ ID NO: 13 (β subunit fragment). SEQ ID NO; 13 is 197 amino acids, so 95% sequence identity corresponds to a minimum of 10 amino acid substitutions. However, the specification does not disclose the structure-function correlation between the structure of the fusion protein of the variant α subunit and variants of SEQ ID NO: 13 (β subunit fragment) and the functions of homodimerization and increased cellular uptake relative to a homodimer of SEQ ID NO: 6. The structure-function correlation is also not taught by the prior art. The person of ordinary skill in the art would have been unable to reasonably predict and visualize the structures of all species of the claimed genus in claim 21.
Claim 24 recites the β-hexosaminidase variant α subunit comprises an amino acid sequence with at least 95% sequence identity to SEQ ID NO: 3. SEQ ID NO: 3 is a fusion protein of the variant α subunit with a β subunit fragment. SEQ ID NO: 3 is 561 amino acids, so 95% identity corresponds to 28 amino acid substitutions. Claim 32 recites that the variant α subunit comprises at least 95% identity to 550 contiguous amino acids of the amino acid sequence according to SEQ ID NO: 3, which is equivalent to 93% identity to SEQ ID NO: 3 (0.95×550/561). 93% sequence identity corresponds to 39 amino acid substitutions. However, the specification does not disclose the structure-function correlation between variants of SEQ ID NO: 3 and the functions of homodimerization and increased cellular uptake relative to a homodimer of SEQ ID NO: 6. The structure-function correlation is also not taught by the prior art. The person of ordinary skill in the art would have been unable to reasonably predict and visualize the structures of all species of the claimed genus in claims 24 and 32.
Claims 44-45, 55-56, and 61 ultimately depend from claim 1 and require the homodimer of the β-hexosaminidase variant α-subunit. Therefore, these claims likewise lack written description support for the genus of β-hexosaminidase variant α-subunits capable of forming a homodimer, wherein the variant subunit further comprises sequence elements that increase cellular uptake of the homodimer relative to SEQ ID NO: 6.
Based upon the above analysis, the person of ordinary skill in the art would not have recognized, at the time the application was filed, that the inventors had possession of the claimed invention.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-4, 34, 44-45, 55-56, and 61 are rejected under 35 U.S.C. 103 as being unpatentable over Mahuran (US 2015/0258180 A1) in view of Matsuoka et al. (Molecular Therapy 18.8 (2010): 1519-1526).
Claim 1 is interpreted as being drawn to the β-hexosaminidase α subunit comprising SEQ ID NO: 1 with the recited amino acid substitutions and one or more sequence elements that increase cellular uptake relative to SEQ ID NO: 6, wherein the subunit is capable of forming a homodimer.
Regarding claims 1-4, Mahuran teaches a recombinant β-hexosaminidase variant subunit, wherein the variant forms a homodimer (Mahuran claim 1). The amino acid sequence of the variant comprises a deletion at position 229 of SEQ ID NO: 1 (Mahuran claim 6) or amino acid substitutions S184K, P209Q, N228S, V230L, T231S, P429Q, K432R, D433K, I436K, N466A, S491R, L493M, T494D, F495D, E498D, L508V, Q513A, N518Y, V519A, F521Y and E523N corresponding to the amino acid numbering set forth in SEQ ID NO: 1 ([0008]). SEQ ID NO: 1 of Mahuran is identical to the instant SEQ ID NO: 1 (OA Appendix A).
Mahuran teaches the β-hexosaminidase variant SEQ ID NO: 2 (Fig. 1), which is identical to the instant SEQ ID NO: 6 (OA Appendix B).
Mahuran does not teach that the variant further comprises one or more amino acid sequence substitutions that increase cellular uptake relative to SEQ ID NO: 6.
Matsuoka teaches amino acid substitutions S51N and A53T in the α-subunit of β-hexosaminidase A increase cellular uptake of the HexA mutant relative to wild-type HexA (Abstract). Matsuoka teaches that these amino acid substitutions result in an additional mannose-6-phosphate (M6P)-type N-glycan, which is recognized by the cellular M6P-receptor (Abstract; Introduction, paragraph bridging left and right columns on page 1519).
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to introduce the amino acid substitutions S51N and A53T in order to increase cellular uptake of the variant (Mahuran’s SEQ ID NO: 2 corresponding to the instant SEQ ID NO: 6). The person of ordinary skill in the art would have had a reasonable expectation of success given that S51N and A53T are distant from the dimerization interface. For example, Mahuran teaches a variant capable of forming a homodimer that omits amino acids 1-87 of SEQ ID NO: 1 (see Mahuran claim 2). Thus, these residues are not required for dimerization.
Regarding claim 34, Mahuran’s SEQ ID NO: 2 (identical to the instant SEQ ID N: 6), which is shown in column 31, does not contain the mutations S51N and A53T. Therefore, the beta-hexosaminidase variant alpha subunit of Mahuran modified by Matsuoka necessarily has an increased mannose-6-phosphorylation at the positions 51 and 53 relative to SEQ ID NO: 6.
Regarding claims 44-45, Mahuran teaches a pharmaceutical composition comprising the β-hexosaminidase variant or protein complex ([0066]). Mahuran also teaches a homodimer of the variant (Mahuran claim 1), which is a protein complex. Mahuran also teaches a pharmaceutical composition comprising a vector encoding the variant ([0066]). Mahuran teaches the pharmaceutical composition further comprises pharmaceutically acceptable carriers or diluents (“excipients”): see [0069].
Regarding claim 55, since Mahuran teaches a variant that forms a homodimer and a polynucleotide encoding the same (Mahuran claims 1 and [0066]), the polynucleotide necessarily encodes the homodimer (the variant binds to itself, so a polynucleotide encoding the variant also encodes the homodimer).
Regarding claim 56, Mahuran teaches a vector comprising a nucleic acid molecule encoding a variant hexosaminidase α-subunit operably linked to a promoter (“gene regulatory region,” see [0018]).
Regarding claim 61, Mahuran teaches treating GM2 gangliosidosis in a subject in need thereof comprising administering to the subject a variant hexosaminidase alpha-subunit or protein complex (“homodimer”) ([0021]). In one embodiment the subject has Tay-Sachs disease (TSD) or Sandhoff disease (SD; [0021]). Mahuran teaches that the variant hexosaminidase hydrolyzes GM2 gangliosides ([0020]), which necessarily reduces GM2 ganglioside accumulation. Mahuran also teaches administering pharmaceutical compositions comprising the variant with dosages that are administered depending on patient needs and on the desired effect (i.e. effective amounts): see [0068].
Mahuran does not teach administering a pharmaceutical composition comprising a homodimer of the β-hexosaminidase variant α subunit with one or more amino acid sequence substitutions that increase cellular uptake relative to SEQ ID NO: 6.
Matsuoka teaches amino acid substitutions S51N and A53T in the α-subunit of β-hexosaminidase A increase cellular uptake of the HexA mutant relative to wild-type HexA (Abstract). Matsuoka teaches that the mutant HexA degrades accumulated GM2 in lysosomes when administered to cultured fibroblasts derived from a Sandhoff disease patient (Abstract).
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to introduce the amino acid substitutions S51N and A53T in order to increase cellular uptake of the variant (Mahuran’s SEQ ID NO: 2 corresponding to the instant SEQ ID NO: 6). The person of ordinary skill in the art would have had a reasonable expectation of success given that S51N and A53T are distant from the dimerization interface. For example, Mahuran teaches a variant capable of forming a homodimer that omits amino acids 1-87 of SEQ ID NO: 1 (see Mahuran claim 2). Thus, these residues are not required for dimerization.
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to administer a pharmaceutical composition comprising a homodimer of the β-hexosaminidase variant α subunit and a pharmaceutically acceptable carrier to a subject with TSD or SD in an effective amount to reduce GM2 ganglioside accumulation in the subject. The person of ordinary skill in the art would have been motivated to use the homodimer of the modified β-hexosaminidase variant α subunit because of its increased cellular uptake. The person of ordinary skill in the art would have had a reasonable expectation of success in administering the pharmaceutical composition to reduce GM2 ganglioside accumulation.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to CANDICE LEE SWIFT whose telephone number is (571)272-0177. The examiner can normally be reached M-F 8:00 AM-4:30 PM (Eastern).
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/LOUISE W HUMPHREY/Supervisory Patent Examiner, Art Unit 1657
/CANDICE LEE SWIFT/Examiner, Art Unit 1657