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 .
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 June 23, 2025 has been entered.
Claims 1, 3, 5-8, 15, 28-29, 35, 38, 44, 46, 51-53, 72, 75-76 and 85-88 are pending.
Claims 44, 46, 51-53, 75 and 76 are withdrawn from further consideration by the examiner, 37 C.F.R. 1.142(b) as being drawn to non-elected inventions.
Claims 1, 3, 5-8, 15, 28-29, 35, 38, 72, and 85-88, drawn to a protein conjugate that read on group (e)
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as the masking agent, (B) polyethyleneimine (PEI) as the species of cell penetrating moiety, (C) single domain antibody as the species of biological payload, are being acted upon in this Office Action.
Priority
Applicant’ claim priority to provisional application 63/275,549, filed November 3, 2021, and 63/348,114, filed June 2, 2022 is acknowledged.
Rejection Withdrawn
The rejection of claim 3 under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph is withdrawn in view of the claim amendment.
The written description rejection of claims 1, 3, 5-8, 12, 15, 28-29, 35, 38, 71 and 85 under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph is withdrawn in view of the claim amendment.
The Declaration of Avidor Shulman under 37 CFR 1.132 filed June 23, 2025 is sufficient to overcome the rejection of claims 1, 3, 5-8, 12, 15, 28-29, 35, 38, 71 and 85 under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103(a) which forms the basis for all obviousness rejections set forth in this Office action:
(a) A patent may not be obtained though the invention is not identically disclosed or described as set forth in section 102 of this title, if the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art to which said subject matter pertains. Patentability shall not be negatived by the manner in which the invention was made.
The factual inquiries set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied for establishing a background for determining obviousness under 35 U.S.C. 103(a) 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 under pre-AIA 35 U.S.C. 103(a), the examiner presumes that the subject matter of the various claims was commonly owned at the time any inventions covered therein were made absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and invention dates of each claim that was not commonly owned at the time a later invention was made in order for the examiner to consider the applicability of pre-AIA 35 U.S.C. 103(c) and potential pre-AIA 35 U.S.C. 102(e), (f) or (g) prior art under pre-AIA 35 U.S.C. 103(a).
Claims 1, 3, 5-8, 15, 35, 72, 85, 86 and 87 are rejected under 35 U.S.C. 103 as being unpatentable over WO2013177421 publication (published November 28, 2013; PTO 892) in view of Meyer et al (J Gene Med 9:797-805, 2007; PTO 1449), Huang et al (Materials Science & Engineering C 102: 558-568, 2019; PTO 892).
Regarding claims 1, 6 and 8, the WO2013177421 publication teaches pH-responsive protein conjugated nanoparticle, e.g., HSA-PEI conjugate comprising human serum albumin (HSA) covalently linked to positively-charged cell penetrating moiety, e.g., polyethyleneimine (PEI) via a linker using suitable crosslinking reagent, e.g., l-ethyl-3-[3-dimethylaminopropyl]carbodiimide (EDC), see para. [0008], [0062]. The reference polyethyleneimine has a molecular weight of less than 2000 Da, e.g., PEI600 Da, see para. [0012], [0075], [0077], [00116] to [00121]. The polyethyleneimine can be branched or linear type, see para. [0010]. The EDC enhances the link between carboxyl group in HSA and amine group on PEI. The low molecular weight pH-sensitive polymer (polyethyleneimine MW 600, PEI600) is conjugated to human serum albumin (HSA) via cross linking agents, resulting in a hyper-cationized pH-responsive APC, see para. [0077]. The WO2013177421 publication teaches that high molecular weight polymers such as PEI (MW 25,000) are useful as transfection agents, but suffer from cytotoxicity. Low molecular weight PEI (MW 600) does not cause cytotoxicity, but is limited due to its inability to facilitate stable condensation with NAs. The conjugation of low molecular weight polymers to a larger molecule such as albumin is thus a useful method of increasing activity of electrostatic complexation with NA condensation while lowing cytotoxicity of LN formulations, see para. [0060]. The WO2013177421 publication teaches albumin also possesses endosomal lytic activity due to its hydrophobic core, which upon conformational change can be exposed and can induce bilayer disruption or membrane fusion. In some embodiments, such as the HSA-PEI600 conjugate, the APC has an ionization profile that is responsive to pH change. The charge density is increased at endosomal pH, which is acidic. See para. [0075]. A low molecular weight pH-sensitive polymer (polyethyleneimine MW 600, PEI600) is conjugated to human serum albumin (HSA) via cross linking agents, resulting in a hyper-cationized pH-responsive APC. The addition of HSA-PEI600 conjugates to LNs significantly increases downregulation of RRM1 (aka RNR Rl) with ASO LOR-2501 (purchased from Alpha DNA) in the presence of serum without substantial cytotoxicity in KB cells (a subline of HeLa), see para. [0077]. The term “comprising” in claim 1 is open ended. It expands to include lipid.
Regarding claim 6, the WO2013177421 publication teaches that up to 20 polycations can be linked to each albumin molecule, which is between 2 and 30 PEI, p. 6, para. [0048]. The term “or” does not require all of a, b, d to j.
Regarding claim 15, the WO2013177421 publication teaches that the payload, e.g., oligonucleotides, such as antisense ODNs, pDNAs, siRNAs, shRNAs, miRs, and anti-miRs, (see para. [0075], [0078]), alpha DNA and Era, see [00126] to [00127] form by ionic complex (aka devoid of a disulfide bond) with the positively charged polyethyleneimine.
Regarding claim 72, the WO2013177421 publication teaches a pharmaceutical composition and pharmaceutically acceptable excipient, see p. 15-16.
Regarding claim 85, the WO2013177421 publication teaches that the HSA-PEI has zeta potential of about 0 to about + 40 mV, which is at least 8 mV, see reference claim 3. Claim 35 is included as it is within the purview of one of ordinary skill in the art to optimize the negative zeta potential to less than -1 mV.
Regarding claim 87, the WO2013177421 publication teaches that the payload is antineoplastic agents (aka devoid of DNA), see reference claim 19, in particular.
The WO2013177421 publication teaches that the albumin-PEI conjugate via disulfide linkages, see p. 20, para. [00118].
The WO2013177421 publication does not teach that the protein conjugate has a negative zeta potential and the PEI is bound to a protecting group by a covalent bond, wherein said protecting group undergoes deprotection at a pH value of less than 7 and is represented by Formula 1:
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However, Meyer teaches poor endosomal release is one major barrier of gene delivery. To overcome this drawback, Meyer teaches melittin (Mel), a 26 amino acid peptide, displays a particularly strong lytic activity and enhances the transfection efficacy of polycations. One major disadvantage of melittin is a high lytic activity at neutral pH, which might lead to toxic side effects before internalization into cells. After internalization of the gene carrier the endosome is acidified, which facilitates the release of therapeutic at acidic pH. Meyer highlights the reversible blocking (aka masking or protecting) of the amino groups NH2 on lysine of proteins, by the use of dimethylmaleic anhydride (DMMAn), see entire document, p. 800, in particular.
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DMMAn modification of melittin was carried out to mask the lytic activity in the extracellular environment (and thus reduce acute toxicity of the carrier). Upon reaction with melittin, the cyclic anhydride precursors undergo ring-opening, resulting in the protecting group bound to the melittin, see Scheme 1 above. No lytic activity was observed at neutral pH; under endosomal acidification at pH 5, cleavage of the protecting groups DMMAn was released and the lytic activity was regained, see Fig. 1, in particular. The reference DMMAn has the claimed formula I wherein n is 0, R and R1 are methyl (aka alkyl). When DMMAn is released, the R1 and R2 method groups are bound together to form a cyclic ring, see scheme 1 above. Meyer further teaches that maleic anhydrides reversibly react with the lysine residues and the N-terminal amino group of peptides and are removed again at slightly acidic, endosomal pH, see p. 803, left col. Meyer further teaches that such targeting and shielding domains have been found advantageous for in vivo gene delivery, see p. 803, right col. Meyer teaches that when the polycation is grafted with DMMAn-Mel, parts of the regulatory polycationic positive charges are masked and acute toxicity and membrane-disruptive interactions are decreased. DMMAn shielding of melittin not only avoids the undesired lytic activity in the extracellular environment, but also further reduces acute toxicity of the core polycation PLL, which is advantageous particularly with regard to systemic in vivo delivery, see p. 804, left col.
Claim 7 is included as Meyer teaches at pH 7.4 (aka between 6 and 8), the protecting group DMMAn is negative charge, e.g., COO-, see p. 800, scheme 1, prior to endosomal acidification, in particular.
Huang teaches that the branched polyethyleneimine (bPEI) has a much higher amine group density than most, if not all, of other amine group-containing polymer, see p. 559, left col. Huang teaches that the bPEI was modified with 2,3-dimethylmaleic anhydride to form pH-triggered charge-reversal nanoparticle, see p. 559, left col. Huang shows that reversible blocking of bPEI with 2,3-dimethylmaleic anhydride (DMA) temporary shield the positive charge of the polymer in bloodstream environment (pH 7.4), as shown in Fig. 4.
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Claim 5 is included as the branched PEI has three kinds of amine groups, primary, secondary and tertiary amines and the primary amines of bPEI are amenable to chemical modification by DMA above. It is within the purview of one of ordinary skill in the art to optimize the % of amine groups of the PEI bound by the protecting group DMA. The claims would have been obvious because "a person of ordinary skill has good reason to pursue the known options within his or her technical grasp. If this leads to the anticipated success, it is likely the product not of innovation but of ordinary skill and common sense". See KSR International Co. v. Teleflex Inc., 82 USPQ2d 1385 (U.S. 2007).
The reference DMA has the claimed formula I wherein n is 0, R and R1 are methyl (aka alkyl). Once located in tumor, the acidic pH-sensitive β-carboxylate amide of DMA-modified bPEI was supposed to be hydrolyzed because of the acidic extracellular environment of solid tumor, regenerating b-PEI-10k and subsequently causing an increase in the permeability of more anticancer drug molecules that entered in tumor tissue, see p. 561, left col. Huang teaches that the pH-triggered zeta potential changes of these modified bPEI-10k and shown in Fig. 5. The zeta (ζ) potentials of bPEI-DMA-1 at pH 7.4 and 6.8 were always negative values during the incubation time period. Only at more acidic pH (6.5) bPEI-DMA-1 showed charge reversal with incubation time, see p. 562, left coll. bPEI-DMA-4 contained zwitterions with a slightly negative charge in bloodstream environment, (pH 7.4). And in tumor acidic environment (pH 6.5 and 6.8), it took a short time to change from negative ζ potentials to positive ones during incubation, see p. 562, left, in particular.
Claims 3 and 86 are included as the conjugate increased accumulation within a biological tissue, e.g., tumor having a pH of less than 7, see p. 562, left, in particular.
It would have been prima facie obvious to a person of ordinary skill in the art before the effective filling date of the claimed invention to combine the teachings of WO2013177421 publication in view of Meyer and Huang by reversibly protecting the cationic HSA-PEI conjugate of the WO2013177421 publication using Meyer’s dimethylmaleic anhydride (DMMAn) or Huang’s 2,3-dimethylmaleic anhydride (DMA) in order to lower the ζ potentials of HSA-PEI from positive to negative by masking the positive charge of PEI at neutral pH and to unmask at acidic pH.
One of ordinary skill in the art would have been motivated to do so because the WO2013177421 publication teaches that the conjugation of low molecular weight polymers PEI to a larger molecule such as albumin is useful for increasing activity of electrostatic complexation with oligonucleotide payload condensation while lowing cytotoxicity and Huang teaches the advantage of using the protecting group 2,3-dimethylmaleic anhydride (DMA) is that the reaction is reversible by blocking the amino groups of HSA-PEI in bloodstream environment (pH 7.4) in order to reduce systemic toxicity (lytic activity); the blocking group DMA could be removed in the endosome at a more acidic pH (6.5). The DMA group could be removed because of the protonic forms of the free carboxylic groups which catalyze the hydrolysis of the amide bonds, see p. 562, left col. and Meyer highlights the reversible blocking (aka masking or protecting or shielding) of the amino groups NH2 on lysine of proteins, by the use of dimethylmaleic anhydride (DMMAn), see entire document, p. 800, in particular.
One of ordinary skill in the art would have been motivated to lower the positively surface charge (zeta potential) of the HSA-PEI to negative zeta potential in order to reduce membrane irritation or damage and higher amount of PEI were toxic to cells.
One of ordinary skill in the art would have had an expectation of success before the effective filling date of the claimed invention to modify the HSA-PEI of WO2013177421 publication in view of Meyer because WO2013177421 publication teaches that the chemically conjugating PEI to HSA significantly lower cytotoxicity of PEI; the HSA component can be recognized by specific receptors on the surface of certain cells, promoting cellular uptake of the conjugate. The PEI portion helps the complex escape from the endosome, allowing the payload to be released into the cytoplasm and Meyer and Huang each teaches that the dimethylmaleic anhydride (DMMAn or DMA) can be used as a protecting group to mask PEI at neutral pH and then undergoes deprotection by hydrolysis of the amide bonds at acidic pH in the endosome of the target cells.
“The combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results.” KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 416 (2007).
“The test of obviousness is not express suggestion of the claimed invention in any or all of the references but rather what the references taken collectively would suggest to those of ordinary skill in the art presumed to be familiar with them.” See In re Rosselet 146 USPQ 183, 186 (CCPA 1965).
“There is no requirement (under 35 USC 103(a)) that the prior art contain an express suggestion to combine known elements to achieve the claimed invention. Rather, the suggestion to combine may come from the prior art, as filtered through the knowledge of one skilled in the art.,” Motorola, Inc, v. Interdigital Tech. Corn., 43 USPQ2d 1481, 1489 (Fed. Cir. 1997).
Accordingly, the claimed invention as a whole was prima facie obvious to one of ordinary skill in the art before the effective filling date of the claimed invention especially in the absence of evidence to the contrary.
Claims 28-29 and 88 are rejected under 35 U.S.C. 103 as being unpatentable over WO2013177421 publication (published November 28, 2013; PTO 892) in view of Meyer et al (J Gene Med 9:797-805, 2007; PTO 1449), Huang et al (Materials Science & Engineering C 102: 558-568, 2019; PTO 892) as applied to claims 1, 3, 5-8, 15, 35, 72, 85, 86 and 87 mentioned above and further in view of Lu et al (US20180055944, published March 1, 2018; PTO 892).
The combine teachings of WO2013177421 publication, Meyer and Huang have been discussed supra. The WO2013177421 publication teaches that the albumin-PEI conjugate via disulfide linkages, see p. 20, para. [00118].
The WO2013177421 publication, Meyer and Huang do not teach that the protein conjugate wherein human serum albumin comprises the amino acid sequence of SEQ ID NO: 1 as per claims 28, 29 and 88.
However, Lu teaches human serum albumin comprising the amino acid sequence of SEQ ID NO: 1, which is identical to the claimed SEQ ID NO: 1, see para [0005], sequence alignment below:
ALIGNMENT:
Query Match 100.0%; Score 3103; Length 585;
Best Local Similarity 100.0%;
Matches 585; Conservative 0; Mismatches 0; Indels 0; Gaps 0;
Qy 1 DAHKSEVAHRFKDLGEENFKALVLIAFAQYLQQCPFEDHVKLVNEVTEFAKTCVADESAE 60
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Db 1 DAHKSEVAHRFKDLGEENFKALVLIAFAQYLQQCPFEDHVKLVNEVTEFAKTCVADESAE 60
Qy 61 NCDKSLHTLFGDKLCTVATLRETYGEMADCCAKQEPERNECFLQHKDDNPNLPRLVRPEV 120
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Db 61 NCDKSLHTLFGDKLCTVATLRETYGEMADCCAKQEPERNECFLQHKDDNPNLPRLVRPEV 120
Qy 121 DVMCTAFHDNEETFLKKYLYEIARRHPYFYAPELLFFAKRYKAAFTECCQAADKAACLLP 180
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Db 121 DVMCTAFHDNEETFLKKYLYEIARRHPYFYAPELLFFAKRYKAAFTECCQAADKAACLLP 180
Qy 181 KLDELRDEGKASSAKQRLKCASLQKFGERAFKAWAVARLSQRFPKAEFAEVSKLVTDLTK 240
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Db 181 KLDELRDEGKASSAKQRLKCASLQKFGERAFKAWAVARLSQRFPKAEFAEVSKLVTDLTK 240
Qy 241 VHTECCHGDLLECADDRADLAKYICENQDSISSKLKECCEKPLLEKSHCIAEVENDEMPA 300
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Db 241 VHTECCHGDLLECADDRADLAKYICENQDSISSKLKECCEKPLLEKSHCIAEVENDEMPA 300
Qy 301 DLPSLAADFVESKDVCKNYAEAKDVFLGMFLYEYARRHPDYSVVLLLRLAKTYETTLEKC 360
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Db 301 DLPSLAADFVESKDVCKNYAEAKDVFLGMFLYEYARRHPDYSVVLLLRLAKTYETTLEKC 360
Qy 361 CAAADPHECYAKVFDEFKPLVEEPQNLIKQNCELFEQLGEYKFQNALLVRYTKKVPQVST 420
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Db 361 CAAADPHECYAKVFDEFKPLVEEPQNLIKQNCELFEQLGEYKFQNALLVRYTKKVPQVST 420
Qy 421 PTLVEVSRNLGKVGSKCCKHPEAKRMPCAEDYLSVVLNQLCVLHEKTPVSDRVTKCCTES 480
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Db 421 PTLVEVSRNLGKVGSKCCKHPEAKRMPCAEDYLSVVLNQLCVLHEKTPVSDRVTKCCTES 480
Qy 481 LVNRRPCFSALEVDETYVPKEFNAETFTFHADICTLSEKERQIKKQTALVELVKHKPKAT 540
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Db 481 LVNRRPCFSALEVDETYVPKEFNAETFTFHADICTLSEKERQIKKQTALVELVKHKPKAT 540
Qy 541 KEQLKAVMDDFAAFVEKCCKADDKETCFAEEGKKLVAASQAALGL 585
|||||||||||||||||||||||||||||||||||||||||||||
Db 541 KEQLKAVMDDFAAFVEKCCKADDKETCFAEEGKKLVAASQAALGL 585
Lu teaches HSA contains a free thiol at C34, which is ideal to conjugate active drug molecules and peptides to it through a sulfhydryl reactive group such as maleimide, see para. [0002]. Albumin has been used as carrier for hydrophobic drug molecules, see para. [0003]. The HSA can be linked to various proteins or peptides of interest directly or indirectly via a linker. Such linkers include cleavable ones and non-cleavable ones, see para. [0024], [0026] to [0027].
It would have been prima facie obvious to a person of ordinary skill in the art before the effective filling date of the claimed invention to combine the teachings of WO2013177421 publication in view of Meyer and Huang in view of Lu by substituting the HSA-PEI in the conjugate of WO2013177421 publication in view of Meyer and Huang for Lu’s human serum albumin comprises the amino acid sequence of SEQ ID NO: 1 in order to link the PEI to the cysteine residue at position 34 through a sulfhydryl reactive group such as maleimide.
One of ordinary skill in the art would have been motivated to mask the charge PEI in HSA-PEI conjugate to lower cytotoxicity using citraconic anhydride because Atassi teaches that citraconic anhydride was the most satisfactory precursor for protecting group, yielding upon deblocking agent for any protein homogenous preparations identical with the respective native proteins in biological properties and in conformational and hydrodynamic parameters, see p. 547, in particular.
One of ordinary skill in the art would have had a reasonable expectation of success in conjugating PEI to HSA via C34 because Lu teaches HSA contains a free thiol at C34, which is ideal to conjugate any protein or drug to it through a sulfhydryl reactive group such as maleimide, see para. [0002].
One of ordinary skill in the art would have had a reasonable expectation of success in making such substitution because of their structural similarity as Lu teaches that human serum albumin has been used as carrier for various proteins and drug molecules, see para. [0003]. In this case, simple substitution of one known element HSA for another HSA comprises SEQ ID NO: 1 would obtain predictable results; a person with ordinary skill has good reason to pursue known options within his or her technical grasp. Note: MPEP 2141 KSR International CO. v. Teleflex Inc. 82 USPQ 2d 1385 (Supreme Court 2007).
“The test of obviousness is not express suggestion of the claimed invention in any or all of the references but rather what the references taken collectively would suggest to those of ordinary skill in the art presumed to be familiar with them.” See In re Rosselet 146 USPQ 183, 186 (CCPA 1965).
“There is no requirement (under 35 USC 103(a)) that the prior art contain an express suggestion to combine known elements to achieve the claimed invention. Rather, the suggestion to combine may come from the prior art, as filtered through the knowledge of one skilled in the art.,” Motorola, Inc, v. Interdigital Tech. Corn., 43 USPQ2d 1481, 1489 (Fed. Cir. 1997).
Accordingly, the claimed invention as a whole was prima facie obvious to one of ordinary skill in the art before the effective filling date of the claimed invention especially in the absence of evidence to the contrary.
Claim 38 is rejected under 35 U.S.C. 103 as being unpatentable over WO2013177421 publication (published November 28, 2013; PTO 892) in view of Meyer et al (J Gene Med 9:797-805, 2007; PTO 1449), Huang et al (Materials Science & Engineering C 102: 558-568, 2019; PTO 892) as applied to claims 1, 3, 5-8, 15, 35, 72, 85, 86 and 87 mentioned above and further in view of Atassi et al (Methods Enzymology 25:546-553, 1972; PTO 1449 filed 5/23/24).
The combine teachings of WO2013177421 publication, Meyer and Huang have been discussed supra.
The references above do not teach that the protein conjugate wherein protecting group is
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as per claim 38.
However, Atassi teaches reversible masking of amino groups is an extremely valuable procedure for protecting these groups from side reactions and reversible masking of amino groups is useful for rendering hydrolysis with trypsin specific for cleavage at arginine residues in proteins and peptides, see p. 546, in particular. Atassi teaches using myoglobin or lysozyme as the protein model and allowing it to react with maleic anhydride or citraconic anhydride. The results of both with myosin and lysozyme showed that of the reagents studies, citraconic anhydride was the most satisfactory, yielding upon deblocking for both myoglobin and lysozyme homogenous preparations identical with the respective native proteins in biological properties and in conformational and hydrodynamic parameters, see p. 547, in particular. The citraconic anhydride (aka 2-methylmaleic anhydride) reacts with amino groups to give two reaction products.
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It would have been prima facie obvious to a person of ordinary skill in the art before the effective filling date of the claimed invention to combine the teachings of WO2013177421 publication in view of Meyer and Huang in view of Atassi by substituting the 2,3-dimethylmaleic anhydride (DMA) for Atassi’s citraconic anhydride (aka 2-methylmaleic anhydride) having similar chemical structure as precursors for the protecting group to mask the change of PEI at neutral pH and to unmask at acidic pH.
One of ordinary skill in the art would have been motivated to mask the charge PEI in HSA-PEI conjugate to lower cytotoxicity using citraconic anhydride because Atassi teaches that citraconic anhydride was the most satisfactory precursor for protecting group, yielding upon deblocking agent for any protein homogenous preparations identical with the respective native proteins in biological properties and in conformational and hydrodynamic parameters, see p. 547, in particular.
One of ordinary skill in the art would have had an expectation of success before the effective filling date of the claimed invention to modify the HSA-PEI of WO2013177421 publication in view of Meyer because WO2013177421 publication teaches that the chemically conjugating PEI to HSA significantly lower cytotoxicity of PEI; the HSA component can be recognized by specific receptors on the surface of certain cells, promoting cellular uptake of the conjugate. The PEI portion helps the complex escape from the endosome, allowing the payload to be released into the cytoplasm and Meyer and Huang each teaches that the dimethylmaleic anhydride (DMMAn or DMA) can be used as a protecting group to mask PEI at neutral pH and then undergoes deprotection by hydrolysis of the amide bonds at acidic pH in the endosome of the target cells. This pH-triggered release of the payload after their translocation into the acidic endosomal compartment of the target cells.
One of ordinary skill in the art would have had a reasonable expectation of success in making such substitution because of their structural similarity as Atassi teaches that citraconic anhydride reacting to amine group by undergo ring-opening, resulting in the protecting bound to the protein, see reaction scheme above.
It would have been obvious to one of ordinary skill in the art to try any of the specifically taught maleic anhydride or citraconic anhydride as precursor for protecting group to mask the charge of PEI as a person with ordinary skill has good reason to pursue known options within his or her technical grasp. Note: MPEP 2141 KSR International CO. v. Teleflex Inc. 82 USPQ 2d 1385 (Supreme Court 2007). Indeed, the common sense of those skilled in the art demonstrates why some combinations would have been obvious where others would not.
“The test of obviousness is not express suggestion of the claimed invention in any or all of the references but rather what the references taken collectively would suggest to those of ordinary skill in the art presumed to be familiar with them.” See In re Rosselet 146 USPQ 183, 186 (CCPA 1965).
“There is no requirement (under 35 USC 103(a)) that the prior art contain an express suggestion to combine known elements to achieve the claimed invention. Rather, the suggestion to combine may come from the prior art, as filtered through the knowledge of one skilled in the art.,” Motorola, Inc, v. Interdigital Tech. Corn., 43 USPQ2d 1481, 1489 (Fed. Cir. 1997).
Accordingly, the claimed invention as a whole was prima facie obvious to one of ordinary skill in the art before the effective filling date of the claimed invention especially in the absence of evidence to the contrary.
Conclusion
No claim is allowed.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to PHUONG HUYNH whose telephone number is (571)272-0846. The examiner can normally be reached on 9:00 a.m. to 6:30 p.m. The examiner can also be reached on alternate alternative Friday from 9:00 a.m. to 5:30 p.m.
If attempts to reach the examiner by telephone are unsuccessful, the examiner's supervisor, Misook Yu, can be reached at 571-270-3497. The fax phone number for the organization where this application or proceeding is assigned is 571-272-0839.
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/PHUONG HUYNH/ Primary Examiner, Art Unit 1641