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 .
Priority
Acknowledgment is made of applicant’s claim for foreign priority under 35 U.S.C. 119 (a)-(d). The certified copy has been filed in parent Application No. 18/559,294, filed on November 6, 2023.
Information Disclosure Statement
The information disclosure statement filed on October 3, 2024 is acknowledged and has been considered by the examiner.
The listing of references in the specification is not a proper information disclosure statement. 37 CFR 1.98(b) requires a list of all patents, publications, or other information submitted for consideration by the Office, and MPEP § 609.04(a) states, "the list may not be incorporated into the specification but must be submitted in a separate paper." Therefore, unless the references have been cited by the examiner on form PTO-892, they have not been considered.
Specification
The abstract of the disclosure is objected to because of the following informality: “an HER2 affibody” in line 3 should be corrected to “a HER2 affibody.” A corrected abstract of the disclosure is required and must be presented on a separate sheet, apart from any other text. See MPEP § 608.01(b).
The disclosure is objected to because of the following informalities:
On pg. 1, line 18; pg. 4, lines 8, 9, and 17; pg. 5, line 5; and pg. 6, line 13, the phrase “an HER2 affibody” is used. This should be corrected to “a HER2 affibody.”
On pg. 5, line 14, “comprsing” should be corrected to “comprising.”
Appropriate correction is required.
Claim Objections
Claims 1-3, 7-8, and 12 are objected to because of the following informalities:
Claims 1, 3, and 8 recite “an HER2 affibody.” This should be revised to “a HER2 affibody.”
In Claim 2, there should be a space between the colon and number 4 in SEQ ID NO: 4 in line 2 of the claim.
Claim 2 contains grammatical errors and appears to be missing words or phrases. The examiner suggests amending the claim after the word “wherein” to “the HER2 affibody has the amino acid sequence as set forth in either SEQ ID NO: 2 or SEQ ID NO: 4 and is modified by bifunctional chelating agents.” The examiner considers this phrase to be equivalent in scope and meaning to the examiner’s interpretation of this claim and to be supported in the specification. The sequence limitation in this suggested revision is also similar in structure and grammar to claim 10.
In claim 7, there should be the phrase “and the” after the semicolon and before the word “reaction.”
In claim 12, “comprsing” should be revised to “comprising.”
In claim 12, it appears there is a word or phrase missing in between “comprsing” and “radioisotope.” The examiner suggests revising the phrase to “comprising a radioisotope.”
Appropriate correction is required.
Claim Interpretation
The examiner interprets the phrase “free of vitamin C and cysteine” in claims 1 and 3 in the context of the affibody composition and method of making to mean that there is no free cysteine amino acid as a buffer component and that the scope of the claim allows for the presence of cysteine residues in the polypeptide chain of the HER2 affibody.
The examiner interprets the phrase “having the amino acid sequence as set forth in SEQ ID NO: 4” in claim 10 and “is set forth in SEQ ID NO: 2 or SEQ ID NO:4” (or the above proposed revisions) in claim 2 to mean that the affibody consists of SEQ ID NO: 4 in claim 10 and SEQ ID NO: 2 or SEQ ID NO: 4 in claim 2. In this interpretation, the affibody proteins are not permitted to contain any other amino acids connected along the main peptide backbone chain connected by an amide/peptide bond, changing the total length of the polypeptide sequence. Thus, an affibody containing another amino acid is understood to not be within the scope of the claimed HER2 affibody limitations.
The examiner interprets claim 8 to be a “product by process” claim, see MPEP § 2113. Accordingly, the claim is only limited by the structure implied by the steps and not the process steps of claim 3. The patentability is based on the product itself. Therefore, art that teaches an imaging agent product comprising a HER2 affibody having a sequence as set forth in SEQ ID NO:2 or SEQ ID NO: 4 that is modified by bifunctional chelating agents that is labeled with 99mTc and contains HEPES, sodium glucoheptonate, and stannous chloride will read on this claim regardless of whether or not the art teaches the method of claim 3.
Claim Rejections - 35 USC § 112(b)
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 1-9 and 12 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.
Regarding claim 1, the term “preferably” in the third line renders the claim indefinite because it is unclear whether the limitation(s) following the phrase are part of the claimed invention. See MPEP § 2173.05(d). for the purpose of examination, the examiner will interpret the scope of the claim to not require the limitations following the term “preferably.” Additionally, claims 2-9 are rejected due to their dependence on claim 1.
Claim 4 recites the limitation "the resulting composition" in the first line of the claim. There is insufficient antecedent basis for this limitation in the claim. It is unclear whether this phrase is referring to the “resulting solution” of the third line of claim 3 or the “resulting HER2 affibody 99mTc marker composition” of the fourth line of claim 3. For the purpose of examination, the examiner will interpret this limitation to refer to the “resulting HER2 affibody 99mTc marker composition” of the fourth line of claim 3. Furthermore, claims 5 and 6 are rejected due to their dependence on claim 4.
In claim 9, the phrase “separate agent” is unclear in meaning. To the examiner’s understanding, this is not a term of the art and the phrase is not defined in the instant specification. It is unclear whether this is meant to mean a “separating agent,” a “contrast agent,” or if it is meant that the imaging agent product is an active pharmaceutical compound that can be used separately from other pharmaceutical compounds. As the meaning of this phrase is unclear, this limitation renders the claim indefinite. For the purpose of examination, the examiner will interpret the scope of this phrase to mean that the product is the HER2 affibody 99mTc marker composition and does not contain (is separate from) other active pharmaceutical compounds.
Regarding claim 12, the phrase "such as" renders the claim indefinite because it is unclear whether the limitations following the phrase are part of the claimed invention. See MPEP § 2173.05(d). For the purpose of examination, the examiner will interpret the scope of the claim to allow for any radioisotope and not require 99mTc.
A broad range or limitation together with a narrow range or limitation that falls within the broad range or limitation (in the same claim) may be considered indefinite if the resulting claim does not clearly set forth the metes and bounds of the patent protection desired. See MPEP § 2173.05(c).
In the present instance, claim 1 recites the broad recitation "a molar ratio of HEPES: sodium glucoheptonate: stannous chloride: HER2 affibody is 2-30:5-40:0.1-5:0.01-0.6", and the claim also recites "further preferably 5-20:10-30:0.2-2:0.03-0.3" and "most preferably 10:20:0.4:0.05" which are narrower statements of the range/limitation. The claim is considered indefinite because there is a question or doubt as to whether the feature introduced by such narrower language is (a) merely exemplary of the remainder of the claim, and therefore not required, or (b) a required feature of the claims. As described above, these molar ratio limitations are not interpreted to limit the scope of claim 1. However, the examiner notes that should claim 1 be amended such that the current phrasing of the molar ratios limits claim 1, the broadest recited range will be the interpreted scope of the limitation for the above reasons.
In the present instance, claim 7 recites the broad recitation ", and the claim also recites "preferably which are narrower statements of the range/limitation. The claim is considered indefinite because there is a question or doubt as to whether the feature introduced by such narrower language is (a) merely exemplary of the remainder of the claim, and therefore not required, or (b) a required feature of the claims. For the purpose of examination, the examiner will interpret the scope of this limitation to be the broader scope and that the limitation after “preferably” does not limit the scope of the claim.
Claim Rejections - 35 USC § 103
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.
Claim 1 is rejected under 35 U.S.C. 103 as being unpatentable over Frejd (US 2024/0124533 A1) in view of Tait (Tait, J. F.; et al., Bioconjugate Chem., 2000 – provided by applicant in IDS filed October 3, 2024).
Frejd teaches HER2 binding polypeptides (Title and Abstract). Specifically, Frejd discloses HER2 binding polypeptides H2BPP1, H2BPP2, AND H2BPP3 having sequences as defined in Figure 1. Frejd describes the H2BPP2 polypeptide as being identical to ZHER2:V2 (pg. 2, [0026]), and describes the polypeptide as a HER2-binding Z variant protein (pg. 2, [0009]), which is a derivative of staphylococcal protein A (pg. 1, [0004]). Frejd teaches that Z variant proteins can be conjugated with chelators such as DOTA and labeled with radionuclides for use in PET or SPECT imaging (pg. 1, [0006]). Frejd also teaches that Z variant proteins may be labeled with 99mTc for imaging applications (pg. 1, [0007]). Frejd teaches that the HER2 polypeptide may be provided as a composition and that the composition may be lyophilized (pg. 5, 0055]). Frejd teaches radiolabeling H2BPP2 with 99mTc (pg. 10, [0131]). This method specifically uses a freeze-dried labeling kit containing stannous chloride and gluconic acid (pg. 10, [0133]).
Frejd does not teach a HER2 affibody lyophilized composition comprising HEPES and sodium glucoheptonate.
Tait teaches a method of radiolabeling a protein with 99mTc (pg. 918, Title and Abstract). More specifically, Tait teaches radiolabeling proteins containing chelating groups defined by amino acid extensions to the peptide chain (pg. 919, left column, paragraph 2). Tait teaches preparing a labeling buffer comprising 10 mmol/L HEPES, 20 mmol/L sodium glucoheptonate, and 128 µg/mL stannous chloride (given the molecular weight of the stannous chloride dihydrate taught by Tait being 225.65 g/mol, this is equivalent to a concentration of 0.57 mmol/L stannous chloride) (pg. 919, right column, paragraph 3). Tait teaches combining the labeling buffer, the 99mTc, and the protein and incubating the reaction at room temperature for 60 minutes (pg. 919, right column, paragraph 3). Tait teaches a similar labeling method to radiolabel a bifunctional chelator modified protein with 99mTc (pg. 919, right column, paragraph 4). Tait teaches that this labeling method successfully radiolabeled the proteins (pg. 921, Table 3 and Figure 4). Tait teaches that most of the radiolabeling was complete after less than 20 minutes (Figure 4). Tait teaches that the radiolabeled proteins can be used for in vivo imaging (pg. 923, Figure 8). Tait described the radiolabeling method as “simple and rapid” (pg. 923, right column, paragraph 2).
A person of ordinary skill in the art would have recognized that both Frejd and Tait teach 99mTc radiolabeling of proteins for use in biomedical imaging applications. It would be recognized that the radiolabeling methods used mostly the same reagents.
It would have been prima facie obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to modify the method of radiolabeling the HER2 binding polypeptide taught by Frejd with the radiolabeling method taught by Tait because the method of Tait is a known and effective alternative method for labeling proteins with 99mTc (MPEP § 2143(I)(B)). It would thus also have been prima facie obvious to a person of ordinary skill in the art to combine the precursor HER2 binding protein of Frejd with the HEPES, sodium glucoheptonate, and stannous chloride of Tait in the same lyophilized formulation because this amounts to combining components useful for the same purpose to form a composition to be used for the very same purpose (MPEP § 2144.06(I)). This would predictably result in a composition comprising a HER2 binding polypeptide, HEPES, sodium glucoheptonate, and stannous chloride.
A person of ordinary skill in the art would have had a reasonable expectation of success in making this modification because the radiolabeling methods of Frejd and Tait are similar. Both methods radiolabel proteins modified with chelating groups with 99mTc using stannous chloride as an oxidizing agent and an organic acid as an exchange agent. The glucoheptonate of Tait and the gluconic acid of Frejd are very similar in structure and serve the same purpose. Furthermore, Frejd teaches that the HER2 binding polypeptide may be lyophilized and combined with other reagents and Tait teaches that the HEPES, sodium glucoheptonate, and stannous chloride can be provided as a lyophilized formulation as well.
The skilled artisan would have been motivated to make this modification because Tait teaches that the buffer and labeling method used is effective at radiolabeling proteins with good radiochemical yield. Additionally, the skilled artisan would have been motivated to combine all the reagents into one lyophilized composition to simplify the radiolabeling process. The artisan would be motivated to exclude the 99mTc because this is a radioactive metal that will decay and thus needs to be prepared relatively close in time to utilization whereas the other components can be stored in the lyophilized form for extended periods of time. By storing more reagents together in one formulation, fewer different reagents need to be reconstituted and less storage space is needed. This would increase the speed and efficiency of the labeling method as well as decreasing the cost.
Regarding claim 1, Frejd teaches the HER2 binding polypeptide H2BPP2, which contains the sequence specified in Figure 1 and is identical to ZHER2:V2 (pg. 2, [0026]). Frejd describes H2BPP2 as a HER2-binding Z variant protein (pg. 2, [0009]), which is a derivative of staphylococcal protein A (pg. 1, [0004]). The instant specification defines an affibody as a scaffold protein derived from staphylococcus aureus protein A (pg. 3, line 7). The sequence of H2BPP2 of Frejd is also mostly identical to SEQ ID NO: 2 and SEQ ID NO: 4 of the instant application. For these reasons, the examiner interprets the H2BPP2 polypeptide of Frejd to be a HER2 binding affibody. Frejd teaches that HER2 polypeptides may be provided as a composition and that the composition may be lyophilized to form a powder (pg. 5, 0055]). Frejd teaches radiolabeling H2BPP2 with 99mTc (pg. 10, [0131]). This method specifically uses a freeze-dried labeling kit containing stannous chloride and gluconic acid (pg. 10, [0133]). Additionally, Tait teaches a method of radiolabeling a protein with 99mTc using a labeling buffer comprising HEPES, sodium glucoheptonate, and stannous chloride (pg. 919, right column, paragraph 3). Tait teaches combining the labeling buffer, the protein, and the 99mTc to perform the labeling reaction (pg. 919, right column, paragraph 3). As described above, it would have been prima facie obvious to substitute the radiolabeling reaction conditions of Frejd with those of Tait. The result of this modification would be a method of radiolabeling a HER2 binding affibody with 99mTc in a buffer containing HEPES, sodium glucoheptonate, and stannous chloride. Additionally, as described above, it would have been prima facie obvious to combine the HER2 binding affibody, HEPES, sodium glucoheptonate, and stannous chloride in the same lyophilized powder because these are reagents being used for the same purpose of preparation of the radionuclide labeled affibody. The result of this modification would be a lyophilized powder of a composition comprising a HER2 affibody, HEPES, sodium glucoheptonate, and stannous chloride. Neither Frejd nor Tait teach including or using vitamin C or cysteine, so this lyophilized powder as taught is considered to be free of both vitamin C and cysteine. Therefore, the combined teachings of Frejd and Tait render claim 1 obvious.
Claims 2-9 are rejected under 35 U.S.C. 103 as being unpatentable over Frejd and Tait as applied to claim 1 above, and further in view of Hofstrom (Hofstrom, C.; et al., J. Med. Chem., 2011).
As described above, Frejd teaches the HER2 binding affibody H2BPP2, which contains the sequence specified in Figure 1 and is identical to ZHER2:V2 (pg. 2, [0026]). Frejd teaches that H2BPP2 was prepared by means of chemical synthesis (pg. 8, [0111]). Frejd teaches that HER2 binding polypeptides may be provided as a composition and that the composition may be lyophilized to form a powder (pg. 5, 0055]). Frejd teaches radiolabeling H2BPP2 with 99mTc (pg. 10, [0131]). This method specifically uses a freeze-dried labeling kit containing stannous chloride and gluconic acid (pg. 10, [0133]). Frejd teaches that HER2 binding affibodies can be conjugated with chelators such as DOTA and labeled with radionuclides for use in PET or SPECT imaging (pg. 1, [0006]). Additionally, Tait teaches a method of radiolabeling a protein with 99mTc using a labeling comprising 10 mmol/L HEPES, 20 mmol/L sodium glucoheptonate, and 128 µg/mL stannous chloride (given the molecular weight of the stannous chloride dihydrate taught by Tait being 225.65 g/mol, this is equivalent to a concentration of 0.57 mmol/L stannous chloride) (pg. 919, right column, paragraph 3). Tait teaches combining the labeling buffer, the protein, and the 99mTc to perform the labeling reaction at room temperature for 60 minutes (pg. 919, right column, paragraph 3). Tait teaches a similar labeling method to radiolabel a bifunctional chelator modified protein with 99mTc (pg. 919, right column, paragraph 4). Tait teaches that the labeling method successfully radiolabeled the proteins (pg. 921, Table 3 and Figure 4). Tait teaches that most of the radiolabeling was complete after less than 20 minutes (Figure 4). Tait described the radiolabeling method as “simple and rapid” (pg. 923, right column, paragraph 2). Furthermore, as described above, the combination of the teachings of Frejd and Tait results in a method of radiolabeling a HER2 binding affibody with 99mTc in a buffer containing HEPES, sodium glucoheptonate, and stannous chloride and a lyophilized powder composition comprising the HER2 binding affibody, HEPES, sodium glucoheptonate, and stannous chloride that is free of both vitamin C and cysteine.
The combined teachings of Frejd and Tait fail to teach a composition comprising HER2 affibody of SEQ ID NO: 2 or SEQ ID NO: 4 modified with bifunctional chelators.
Hofstrom teaches radiolabeled affibody proteins (pg. 3817, Abstract). More specifically, Hofstrom teaches HER2 binding affibody proteins (pg. 3818, left column, second paragraph and Figure 1). Hofstrom teaches that these affibodies may contain or be modified with chelating groups, including a bifunctional DOTA chelator (pg. 3818, Figure 2). Hofstrom teaches the modification of a HER2 affibody with an N-terminal HEHEHE tag (Figure 1). Hofstrom teaches that the HEHEHE tag enables the use of IMAC to purify the affibody protein (pg. 3818, left column, paragraph 3; pg. 3818-3819, Production and Purification of Affibody Molecules). Hofstrom teaches that while a 6xHis tag can similarly be used to purify the HER2 affibody, the 6xHis tag results in significantly increased off-target liver accumulation of the radiolabeled affibody (pg. 3820, Figure 4). Furthermore, the HEHEHE tag decreases off-target distribution compared to the affibody lacking an N-terminal tag, indicating that the HEHEHE tag imparts favorable biodistribution properties on the affibody (Figures 4-6). Hofstrom also teaches that the HEHEHE tag does not prevent affibody binding to HER2 protein (pg. 3820, Table 3). Hofstrom further teaches radiolabeling the HEHEHE modified HER2 binding affibody with 99mTc using sodium gluconate, stannous chloride (pg. 3824, right column, paragraph 3). Hofstrom concludes that the HEHEHE tag permits efficient and simple affibody purification, has no negative effect on affinity for the target receptor, is compatible with multiple radiolabeling chemistries, and can improve radiopharmaceutical biodistribution (pg. 3823, paragraph 4). Hofstrom also suggests using HEHEHE tags for purification of other affibody molecules and targeting probes irrespective of labeling chemistry (pg. 3823, right column, paragraph 1).
A person of ordinary skill in the art would have recognized that both Frejd and Hofstrom teach HER2 binding affibody proteins. It would be recognized that each of Frejd, Hofstrom, and Tait teach radiolabeling proteins with 99mTc for biological imaging applications. It would be recognized that Hofstrom teaches that the addition of the HEHEHE tag to the N-terminus of a HER2 affibody imparts favorable properties such as simple purification and improved biodistribution.
It would have been prima facie obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to modify the H2BPP2 HER2 binding affibody of Frejd with the HEHEHE N-terminal tag of Hofstrom because Hofstrom teaches that the HEHEHE tag imparts the ability to purify the protein using IMAC, is compatible with multiple radiolabeling chemistries, and can improve biodistribution of radiolabeled affibody (MPEP § 2143(I)(C)) and because Hofstrom suggests incorporating the HEHEHE tag on other affibody and targeted radiopharmaceutical compounds (MPEP § 2143(I)(G)). It also would have been prima facie obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to modify the affibody with a bifunctional chelator as taught by Hofstrom, as this is a known alternative group for radionuclide labeling (MPEP § 2143(I)(B)) and because Hofstrom teaches that this is a suitable chelating group for HEHEHE modified HER2 binding affibodies (MPEP § 2143(I)(G)). This would have the predictable result of a HER2 binding affibody protein of the sequence of H2BPP2 modified with HEHEHE at the N-terminus and a bifunctional chelator (and corresponding lyophilized compositions containing this affibody and methods of radiolabeling as discussed above).
A person of ordinary skill in the art would have had a reasonable expectation of success in making this modification because Hofstrom teaches adding an N-terminal HEHEHE tag and bifunctional chelator to a HER2 binding affibody protein, which is similar to the HER2 affibody protein of Frejd.
The skilled artisan would have been motivated to incorporate the HEHEHE tag because Hofstrom teaches that the HEHEHE tag permits efficient and simple affibody purification, has no negative effect on affinity for the target receptor, is compatible with multiple radiolabeling chemistries, and can improve radiopharmaceutical biodistribution (pg. 3823, paragraph 4). Hofstrom also suggests using HEHEHE tags for purification of other affibody molecules. The skilled artisan would also be motivated to incorporate the bifunctional chelator to provide another means of specifically coordinating a radionuclide. As different chelators can have different affinities for different radionuclides, the use of a bifunctional chelator such as a DOTA derivative may enable different selection of radionuclides for therapeutic or diagnostic uses of the affibody.
Regarding claim 2, as described above, the combination of the teachings of Frejd and Tait results in a lyophilized powder composition comprising the HER2 binding affibody, HEPES, sodium glucoheptonate, and stannous chloride that is free of both vitamin C and cysteine. Frejd teaches the HER2 binding affibody H2BPP2 (Figure 1). Additionally, Hofstrom teaches the incorporation of an N-terminal HEHEHE tag on a HER2 binding affibody (Figure 1). As described above, it would have been prima facie obvious to incorporate an N-terminal HEHEHE tag on the H2BPP2 affibody of Frejd. This would result in an affibody having an amino acid sequence 100% identical to that of SEQ ID NO: 2 of the instant application and claim 2. The examiner notes that while Hofstrom depicts the inclusion of an additional methionine residue at the N-terminus of the affibody sequence (Figure 1), Hofstrom specifically teaches the benefits of the HEHEHE sequence and does not provide a motivation to include a methionine in the affibody sequence. The skilled artisan would recognize that Hofstrom teaches producing the affibody in E. coli, which requires an AUG start codon coding for methionine to begin the translation of the protein. Thus, the methionine is a byproduct of the E. coli expression system. However, Frejd teaches chemical synthesis of the affibody protein (pg. 8, [0111]), which would enable the incorporation of the beneficial HEHEHE tag without the requirement to add the methionine residue. Therefore, the result of the modification taught by Hofstrom applied to Frejd is indeed identical to instantly claimed SEQ ID NO: 2. Additionally, Frejd teaches that HER2 binding affibodies can be conjugated with chelators such as DOTA and labeled with radionuclides for use in PET or SPECT imaging (pg. 1, [0006]). Hofstrom specifically teaches labeling HEHEHE tagged affibody with a maleimido-monoamide-DOTA (Figure 2; Tables 2 and 3; and Figures 4-6). Thus, the result of this modification would be a HER2 binding affibody of instantly claimed SEQ ID NO: 2 modified with a bifunctional chelator. Furthermore, as described above, the combination of Frejd and Tait teach the incorporation of such an affibody in a lyophilized powder of claim 1 (containing HEPES, sodium glucoheptonate, and stannous chloride that is free of vitamin C and cysteine). Therefore, the combined teachings of Frejd, Tait, and Hofstrom render claim 2 obvious.
Regarding claim 3, Frejd teaches a method of preparing a HER2 affibody labeled with 99mTc (pg. 10, [0133]). Frejd also teaches that in the embodiment in which the HER2 affibody is provided as a lyophilized powder, the process of preparation includes the first step of reconstituting the powder in a suitable buffer for radiolabeling (pg. 5-6, [0065]). For the reasons described above in the rejection of claim 1, it would have been prima facie obvious to modify the method of Frejd using the radiolabeling conditions taught by Tait. Tait teaches a method of radiolabeling a protein with 99mTc using a labeling comprising 10 mmol/L HEPES, 20 mmol/L sodium glucoheptonate, and 128 µg/mL (0.57 mmol/L) stannous chloride (pg. 919, right column, paragraph 3). As described above, the combined teachings of Frejd, Tait, and Hofstrom render the precursor composition of claim 2 obvious. Tait teaches combining the labeling buffer, the protein, and the 99mTc to perform the labeling reaction (pg. 919, right column, paragraph 3). Thus, the combined method would involve reconstituting the lyophilized protein (as taught by Frejd) and the labeling buffer reagents (as taught by both Frejd and Tait). The examiner interprets this to read on dissolving the precursor composition, as Frejd describes the process as reconstituting the lyophilized powder in a suitable buffer for radiolabeling (pg. 5-6, [0065]). Furthermore, Tait teaches that 100 µg of protein can be labeled with 10,000 µCi of 99mTc (pg. 920, left column, last paragraph). As 10,000 µCi is within the claimed range of 500-20,000 µCi, it renders this claimed range obvious (MPEP § 2144.05(I)). Additionally, Tait teaches performing the labeling reaction at room temperature for 60 minutes (pg. 919, right column, paragraph 3). As 60 minutes is within the claimed range of 5-60 min, it renders the claimed range obvious. Additionally, Tait teaches that most of the radiolabeling was complete after less than 20 minutes (Figure 4). Furthermore, as Tait describes capping vials and degassing solvents in the preparation of the radiolabeled protein, the examiner interprets this to read on performing the reaction under sealed conditions (pg. 919, right column, paragraph 3). Additionally, Hofstrom explicitly teaches 99mTc radiolabeling of a HER2 binding affibody under argon gas in a sealed vial (pg. 3824, right column, paragraph 3). Furthermore, for the reasons described above, the lyophilized powder taught by the combination of Frejd, Tait, and Hofstrom is interpreted to be free of vitamin C and cysteine. Additionally, Tait does not teach adding either vitamin C or cysteine during the radiolabeling process, so the examiner interprets the resulting composition after the radiolabeling reaction to also be free of vitamin C and cysteine. Therefore, the combined teachings of Frejd, Tait, and Hofstrom render claim 3 obvious.
Regarding claims 4 and 5, Tait teaches a method of radiolabeling a protein with 99mTc using a labeling comprising 10 mmol/L HEPES, 20 mmol/L sodium glucoheptonate, and 128 µg/mL (0.57 mmol/L) stannous chloride (pg. 919, right column, paragraph 3). Tait further teaches combining 100 µg of protein (in 100 µL volume) with 200 µL of this reconstituted buffer (pg. 919, right column, paragraph 3). However, as the combined lyophilized powder of claim 2 rendered obvious above already contains the affibody protein, this protein solution addition step is not required. Tait teaches a separate addition of 100 µL of the 99mTc containing solution (pg. 919, right column, paragraph ). Thus, the solution containing 100 µg of protein, 10 mmol/L HEPES, 20 mmol/L sodium glucoheptonate, and 0.57 mmol/L stannous chloride, which is at a volume of 200 µL as taught by Tait, is diluted to a final volume of 300 µL by the addition of the 99mTc solution. Thus, the final concentrations of the components in the resulting composition is 0.33 mg/mL protein, 6.7 mmol/L HEPES, 13.3 mmol/L sodium glucoheptonate, and 0.37 mmol/L stannous chloride. Given that the molecular weight of SEQ ID NO: 2 of the instant application is 7455 g/mol and the molecular weight of the maleimido-monoamide-DOTA of Hofstrom is about 526 g/mol, the molecular weight of the bifunctional chelator modified HER2 binding affibody taught by the combination of the above references is ~7981 g/mol. Thus, 0.67 mg/mL protein is equivalent to 0.041 mmol/L affibody concentration in the resulting composition. As the final composition concentration values for each of HEPES, sodium glucoheptonate, stannous chloride, and HER2 affibody is within the claimed ranges of each of claims 4 and 5, the teachings render these claimed ranges obvious (MPEP § 2144.05(I)). Additionally, Tait teaches using the HEPES-based radiolabeling buffer with a pH of 6.6 (pg. 919, right column, paragraph 3). As this value is within each of the claimed pH ranges of claims 4 and 5, this renders both claimed ranges obvious. Therefore, the combined teachings of Frejd, Tait, and Hofstrom render claims 4 and 5 obvious.
Regarding claim 6, as described above, the combined teachings of Frejd, Tait, and Hofstrom teach a method of radiolabeling a HER2 binding affibody of SEQ ID NO:2 wherein the resulting composition contains 6.7 mmol/L HEPES, 13.3 mmol/L sodium glucoheptonate, 0.37 mmol/L stannous chloride, and 0.041 mmol/L HER2 affibody and has a pH of 6.6. The pH value is the same as the claimed value, rendering this limitation obvious. While the concentrations of the HEPES, sodium glucoheptonate, stannous chloride, and HER2 affibody are not equal to the exact values claimed in claim 6, the difference between the teachings and the claim amounts to a difference in concentration. Per MPEP § 2144.05(II), differences in concentration generally do not support patentability unless there is evidence indicating such a concentration is critical. As the art teaches each of these composition components, it would have taken no more than the relative skills of one of ordinary skill in the art to have arrived at the claimed concentrations through routine optimization and experimentation. The skilled artisan would have been motivated to optimize these concentrations in order to optimize radiolabeling yield and stability of the final product. The skilled artisan would have had a reasonable expectation of success because changing concentrations of buffer components and reagents is a standard procedure in radiopharmaceutical chemistry and the changing in concentration of individual components such as stannous chloride merely amounts to changing how much of a salt is dissolved in the preparation of the original solution. Thus, the claimed concentration values of HEPES, stannous chloride, sodium glucoheptonate, and affibody protein are rendered obvious. Therefore, the combined teachings of Frejd, Tait, and Hofstrom render claim 6 obvious.
Regarding claim 7, Tait teaches the addition of 10 mCi (equivalent to 10,000 µCi) to 100 µg protein in a radiolabeling reaction (pg. 920, left column, last paragraph). As this value is within the claimed range of 2000-10,000 µCi, it renders the claimed range obvious (MPEP § 2144.05(I)). Additionally, while in one embodiment, Tait teaches radiolabeling the protein over a period of 60 minutes (pg. 919, right column, paragraph 3), Tait also teaches stopping the labeling at earlier timepoints and demonstrates that high labeling yield can occur at timepoints shorter than 20 minutes, including timepoints between 10 and 15 minutes (Figure 4). In view of this, the skilled artisan would optimize time of radiolabeling through routine optimization. The skilled artisan would be motivated to optimize labeling time because faster labeling will enable faster product of the final product, which can save money and maximize the radioactivity of the final product (less decay of the radionuclide label). Therefore, the claimed reaction time range is rendered obvious in the absence of evidence of criticality. Therefore, the combined teachings of Frejd, Tait, and Hofstrom render claim 7 obvious.
Regarding claim 8, as described in the Claim Interpretation section above, the examiner interprets claim 8 as a “product by process” claim. Therefore, art that teaches an imaging agent product comprising a HER2 affibody having a sequence as set forth in SEQ ID NO:2 or SEQ ID NO: 4 that is modified by bifunctional chelating agents that is labeled with 99mTc and contains HEPES, sodium glucoheptonate, and stannous chloride will read on this claim regardless of whether or not the art teaches the method of claim 3. As described above, the combination of Frejd, Tait, and Hofstrom render obvious the composition of claim 2 and teach a HER2 binding affibody of SEQ ID NO: 2 of the instant application modified with a bifunctional chelator. Furthermore, as described above, the product of the radiolabeling method taught by Tait applied to the HER2 binding affibody would result in a final composition comprising HEPES, sodium glucoheptonate, stannous chloride, and the 99mTc-labeled HER2 affibody modified with a bifunctional chelator and have a pH of 6.6. Furthermore, though it is not required to read on claim 8, as described above, the combined teachings of Frejd, Tait, and Hofstrom render the method of claim 3 obvious. As Frejd teaches that radionuclide labeled HER2 binding affibodies can be used for PET and SPECT (pg. 1, [0006] and [0007]; and Figure 12), Hofstrom similarly teaches that radionuclide labeled HER2 binding affibodies can be used for in vivo imaging (pg. 3823, left column, paragraph 3), and Tait teaches the use of 99mTc-labeled protein for in vivo imaging (Figure 8), the examiner interprets the 99mTc-labeled HER2 affibody composition to be an imaging agent product. Therefore, the combined teachings of Frejd, Tait, and Hofstrom render claim 8 obvious.
Regarding claim 9, Frejd teaches the use of 99mTc-labeled HER2 affibody for SPECT/CT imaging in vivo (Figure 12; and pg. 14, [0155]). Therefore, the examiner interprets the 99mTc radiolabeled imaging agent product of claim 8 to be a SPEC imaging agent. Additionally, as the combined teachings teach the production of this product independent of other pharmaceutical agents and Frejd describe the use of a 99mTc-labeled affibody on its own without other pharmaceutical agents, the examiner interprets this imaging agent product to be a separate agent (see above Claim Interpretation). Separately and additionally, Frejd teaches performing HER2 affibody radiolabeling using a kit containing freeze dried components of the labeling reaction (pg. 10, [0132]). Furthermore, Hofstrom also teaches using a kit (pg. 3824, right column, paragraph 3). Thus, it would have been prima facie obvious to provide the imaging agent product as a kit. Therefore, the combined teachings of Frejd, Tait, and Hofstrom render claim 9 obvious.
Claim 10 is rejected under 35 U.S.C. 103 as being unpatentable over Frejd in view of Hofstrom and Lindberg (Lindberg, H.; et al., Tumor Biol., 2012).
As described above, Frejd teaches HER2 binding polypeptides H2BPP1, H2BPP2, AND H2BPP3 having sequences as defined in Figure 1. Frejd describes the H2BPP2 polypeptide as being identical to ZHER2:V2 (pg. 2, [0026]), and describes the polypeptide as a HER2-binding Z variant protein (pg. 2, [0009]), which is a derivative of staphylococcal protein A (pg. 1, [0004]). Frejd teaches that Z variant proteins can be conjugated with chelators such as DOTA and labeled with radionuclides for use in PET or SPECT imaging (pg. 1, [0006]). Frejd also teaches that Z variant proteins may be labeled with 99mTc for imaging applications (pg. 1, [0007]). Frejd teaches that the HER2 polypeptide may be provided as a composition and that the composition may be lyophilized (pg. 5, 0055]). Frejd teaches radiolabeling H2BPP2 with 99mTc (pg. 10, [0131]). This method specifically uses a freeze-dried labeling kit containing stannous chloride and gluconic acid (pg. 10, [0133]).
Frejd fails to teach a HER2 affibody having the amino acid sequence as set forth in SEQ ID NO: 4 of the instant application.
As described above, Hofstrom teaches radiolabeled affibody proteins (pg. 3817, Abstract). More specifically, Hofstrom teaches HER2 binding affibody proteins (pg. 3818, left column, second paragraph and Figure 1). Hofstrom teaches that these affibodies may contain or be modified with chelating groups, including a bifunctional DOTA chelator (pg. 3818, Figure 2). Hofstrom teaches the modification of a HER2 affibody with an N-terminal HEHEHE tag (Figure 1). Hofstrom teaches that the HEHEHE tag enables the use of IMAC to purify the affibody protein (pg. 3818, left column, paragraph 3; pg. 3818-3819, Production and Purification of Affibody Molecules). Hofstrom teaches that while a 6xHis tag can similarly be used to purify the HER2 affibody, the 6xHis tag results in significantly increased off-target liver accumulation of the radiolabeled affibody (pg. 3820, Figure 4). Furthermore, the HEHEHE tag decreases off-target distribution compared to the affibody lacking an N-terminal tag, indicating that the HEHEHE tag imparts favorable biodistribution properties on the affibody (Figures 4-6). Hofstrom also teaches that the HEHEHE tag does not prevent affibody binding to HER2 protein (pg. 3820, Table 3). Hofstrom further teaches radiolabeling the HEHEHE modified HER2 binding affibody with 99mTc using sodium gluconate, stannous chloride (pg. 3824, right column, paragraph 3). Hofstrom concludes that the HEHEHE tag permits efficient and simple affibody purification, has no negative effect on affinity for the target receptor, is compatible with multiple radiolabeling chemistries, and can improve radiopharmaceutical biodistribution (pg. 3823, paragraph 4). Hofstrom also suggests using HEHEHE tags for purification of other affibody molecules and targeting probes irrespective of labeling chemistry (pg. 3823, right column, paragraph 1).
Lindberg teaches HER2 binding affibody proteins radiolabeled with 99mTc (pg. 641, Title and Abstract). More specifically, Lindberg teaches affibodies of four sequences (pg. 643, Figure 2) that differ in the presence or absence of an N-terminal HEHEHE tag and the presence or identity of a C-terminal chelating peptide moiety. Lindberg teaches radiolabeling the affibodies with 99mTc using stannous chloride and sodium gluconate (pg. 644, right column, paragraphs 1-2). Lindberg teaches that a HEHEHE affibody lacking a C-terminal chelating peptide can also bind to 99mTc (pg. 650, left column; and Figure 6). Lindberg teaches that the affibody containing both the N-terminal HEHEHE tag and the C-terminal GGGC and the affibody containing just the N-terminal HEHEHE tag differ in biodistribution (pg. 649, Table 1; and pg. 650, Figure 9). Lindberg teaches that radiolabeling of the affibody containing HEHEHE but not GGGC is of lower efficiency (pg. 650, left column), but teaches that this affibody is still suitable as a tracer agent when it does not depend on peptide-based chelators to bind the radionuclide (pg. 650, right column, paragraph 2).
A person of ordinary skill in the art would have recognized that each of Frejd, Hofstrom, and Lindberg teach 99mTc radiolabeled HER2 binding polypeptides that can be used for biomedical imaging applications. It would be recognized that Hofstrom teaches that the addition of a HEHEHE tag to the N-terminus of a HER2 affibody imparts favorable properties such as simple purification and improved biodistribution. It would also be recognized that Lindberg teaches that HER2 affibodies containing an N-terminal HEHEHE tag do not require a C-terminal peptide-based chelator moiety to be effective and that removal of such peptide-based chelator can further tailor the biodistribution of the imaging agent.
It would have been prima facie obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to modify the H2BPP2 HER2 binding polypeptide of Frejd with the HEHEHE N-terminal tag of Hofstrom and Lindberg because Hofstrom and Lindberg teach that the HEHEHE tag imparts the ability to purify the protein using IMAC, is compatible with multiple radiolabeling chemistries, and can improve biodistribution of radiolabeled affibody (MPEP § 2143(I)(C)) and because Hofstrom suggests incorporating the HEHEHE tag on other affibody and targeted radiopharmaceutical compounds (MPEP § 2143(I)(G)). It also would have been prima facie obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to modify the polypeptide by removing the C-terminal GGC peptide-based chelator, as taught by Lindberg, because Lindberg teaches that the removal of such a peptide-based chelator from a HEHEHE tagged affibody can further tailor biodistribution and provide an alternative imaging agent (MPEP § 2143(I)(C) and 2143(I)(G)). This would have the predictable result of a HER2 binding polypeptide of the sequence of H2BPP2 modified with HEHEHE at the N-terminus and the removal of the C-terminal GGC amino acids.
A person of ordinary skill in the art would have had a reasonable expectation of success in making these modifications because Lindberg teaches that HER2 binding affibody sequences can be modified through both the introduction of N-terminal HEHEHE tags and modification or removal of C-terminal peptide-based chelating groups (Figure 2). Additionally, Hofstrom teaches adding an N-terminal HEHEHE tag to a HER2 binding affibody. It would be recognized that the HER2 binding affibodies of Lindberg and Hofstrom are very similar in sequence to the H2BPP2 of Frejd, suggesting that the same modifications could be applied to Frejd.
The skilled artisan would have been motivated to make these modifications because Hofstrom teaches that the HEHEHE tag permits efficient and simple affibody purification, has no negative effect on affinity for the target receptor, is compatible with multiple radiolabeling chemistries, and can improve radiopharmaceutical biodistribution (pg. 3823, paragraph 4). Hofstrom also suggests using HEHEHE tags for purification of other affibody molecules. Additionally, Lindberg also teaches similar benefits to the HEHEHE tag in HER2 binding polypeptides. The skilled artisan would also be motivated to remove the C-terminal GGC peptide-based chelating group because Lindberg teaches that when the HEHEHE tag is present, removal of such a group can further modulate biodistribution and results in a protein still suitable for use as an imaging agent.
Regarding claim 10, Frejd teaches the HER2 binding polypeptide H2BPP2, which contains the sequence specified in Figure 1 and is identical to ZHER2:V2 (pg. 2, [0026]). Frejd describes H2BPP2 as a HER2-binding Z variant protein (pg. 2, [0009]), which is a derivative of staphylococcal protein A (pg. 1, [0004]). The instant specification defines an affibody as a scaffold protein derived from staphylococcus aureus protein A (pg. 3, line 7). The sequence of H2BPP2 of Frejd is also mostly identical to SEQ ID NO: 2 and SEQ ID NO: 4 of the instant application. For these reasons, the examiner interprets the H2BPP2 polypeptide of Frejd to be a HER2 binding affibody. Additionally, Hofstrom teaches the incorporation of an N-terminal HEHEHE tag on a HER2 binding affibody (Figure 1). Furthermore, Lindberg teaches both the addition of an N-terminal HEHEHE tag and the removal of a C-terminal peptide-based chelating group (Figure 2). As described above, it would have been prima facie obvious to incorporate the N-terminal HEHEHE tag and remove the C-terminal GGC peptide-based chelator on the H2BPP2 affibody of Frejd. This would result in an affibody having an amino acid sequence 100% identical to that of SEQ ID NO: 4 of the instant application and claim 10. The examiner notes that while Hofstrom (Figure 1) and Lindberg (Figure 2) depicts the inclusion of an additional methionine residue at the N-terminus of the affibody sequence, Hofstrom and Lindberg specifically teach the benefits of the HEHEHE sequence and do not provide a related motivation to include a methionine in the affibody sequence. The skilled artisan would recognize that Hofstrom and Lindberg teach producing the affibody in E. coli, which requires an AUG start codon coding for methionine to begin the translation of the protein. Thus, the methionine is a byproduct of the E. coli expression system. However, Frejd teaches chemical synthesis of the affibody protein (pg. 8, [0111]), which would enable the incorporation of the beneficial HEHEHE tag without the requirement to add the methionine residue. Therefore, the result of the modifications taught by Hofstrom and Lindberg applied to Frejd is indeed identical to instantly claimed SEQ ID NO: 4. While none of Frejd, Hofstrom, nor Lindberg explicitly describe such an affibody as “truncated,” the examiner interprets the removal of a C-terminal group of amino acids from a polypeptide chain to be consistent with the meaning of the term truncation in the polypeptide art, thus reading on this limitation. Furthermore, the claim is limited by its structural limitations, which are the provided sequence of SEQ ID NO: 4. As the combined teachings result in a polypeptide having the exact sequence as SEQ ID NO: 4, this product reads on all structural limitations of claim 10. Therefore, the combined teachings of Frejd, Hofstrom, and Lindberg render claim 10 obvious.
Claims 11 and 12 are rejected under 35 U.S.C. 103 as being unpatentable over Frejd, Hofstrom, and Lindberg as applied to claim 10 above, and further in view of Perols (Perols, A.; et al., Bioconjugate Chem., 2012).
As described above, Frejd teaches the HER2 binding affibody H2BPP2, which contains the sequence specified in Figure 1 and is identical to ZHER2:V2 (pg. 2, [0026]). Frejd teaches that H2BPP2 was prepared by means of chemical synthesis (pg. 8, [0111]). Frejd teaches radiolabeling H2BPP2 with 99mTc (pg. 10, [0131]). Frejd teaches that HER2 binding affibodies can be conjugated with chelators such as DOTA and labeled with radionuclides for use in PET or SPECT imaging (pg. 1, [0006]).
Additionally, Hofstrom teaches HER2 binding affibody proteins (pg. 3818, left column, second paragraph and Figure 1). Hofstrom teaches that these affibodies may contain or be modified with chelating groups, including a bifunctional DOTA chelator (pg. 3818, Figure 2). Hofstrom teaches the modification of a HER2 affibody with an N-terminal HEHEHE tag (Figure 1). Hofstrom teaches that the HEHEHE tag enables the use of IMAC to purify the affibody protein (pg. 3818, left column, paragraph 3; pg. 3818-3819, Production and Purification of Affibody Molecules). Hofstrom concludes that the HEHEHE tag permits efficient and simple affibody purification, has no negative effect on affinity for the target receptor, is compatible with multiple radiolabeling chemistries, and can improve radiopharmaceutical biodistribution (pg. 3823, paragraph 4). Hofstrom also suggests using HEHEHE tags for purification of other affibody molecules and targeting probes irrespective of labeling chemistry (pg. 3823, right column, paragraph 1).
Additionally, Lindberg teaches HER2 binding affibody proteins radiolabeled with 99mTc (pg. 641, Title and Abstract). More specifically, Lindberg teaches affibodies of four sequences (pg. 643, Figure 2) that differ in the presence or absence of an N-terminal HEHEHE tag and the presence or identity of a C-terminal chelating peptide moiety. Lindberg teaches radiolabeling the affibodies with 99mTc using stannous chloride and sodium gluconate (pg. 644, right column, paragraphs 1-2). Lindberg teaches that the affibody containing both the N-terminal HEHEHE tag and the C-terminal GGGC and the affibody containing just the N-terminal HEHEHE tag differ in biodistribution (pg. 649, Table 1; and pg. 650, Figure 9). Lindberg teaches that radiolabeling of the affibody containing HEHEHE but not GGGC is of lower efficiency (pg. 650, left column), but teaches that this affibody is still suitable as a tracer agent when it does not depend on peptide-based chelators to bind the radionuclide (pg. 650, right column, paragraph 2).
Furthermore, as described above, the combined teachings of Frejd, Hofstrom, and Lindberg teach a HER2 affibody having the amino acid sequence as set forth in SEQ ID NO: 4 of the instant application.
The combined teachings of Frejd, Hofstrom, and Lindberg fail to explicitly teach a HER2 affibody having an amino acid sequence as set forth in SEQ ID NO: 4 that is modified by a bifunctional chelating agent.
Perols teaches radiolabeling HER2 binding affibodies with bifunctional chelators (pg. 1661, Abstract). More specifically, Perols teaches the synthesis of HER2 binding affibodies lacking a C-terminal peptide-based chelator conjugated to DOTA chelating groups at three different positions in the protein (N-terminus, Lysine 50, and Lysine 58) (pg. 1661, Abstract Figure; pg. 1662, right column, last paragraph; and pg. 1663, left column, first paragraph). Perols teaches that the DOTA was attached to primary amine groups on the affibody (pg. 1663, left column, first paragraph). Perols teaches radiolabeling the DOTA-modified affibodies with a radionuclide (pg. 1663, paragraph 5). Perols also teaches using the radiolabeled affibody for SPECT/CT imaging (pg. 1668, Figure 9). Perols teaches that DOTA conjugation location has only a small effect on HER2 affinity (Table 1; and pg. 1667, left column) and that all conjugates could target HER2 in vivo (Figure 5; and pg. 1667, right column, paragraph 3).
A person of ordinary skill in the art would have recognized that each of Frejd, Hofstrom, Lindberg, and Perols teach radiolabeled HER2 affibodies. It would also be recognized that each of Frejd, Hofstrom, and Perols teach that such affibodies can be modified with bifunctional chelators.
It would have been prima facie obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to modify the HER2 binding affibody having the same sequence as SEQ ID NO: 4 taught by the combination of Frejd, Hofstrom, and Lindberg by conjugating a chelating group such as DOTA as taught by Perols because Perols teaches that this is an effective way to radiolabel HER2 affibodies and because Lindberg suggests using chelators (such as polyamino-carboxylate chelators like DOTA) in HER2 affibodies lacking a C-terminal peptide-based chelating group (pg. 650, right column, paragraph 2) (MPEP § 2143(I)(G)). This modification would predictably result in a HER2 affibody of SEQ ID NO: 4 modified by bifunctional chelating agents.
A person of ordinary skill in the art would have had a reasonable expectation of success in making this modification because the HER2 affibody Perols teaches performing this modification to is similar in sequence and structure to that of the combination of Frejd, Hofstrom, and Lindberg). Additionally, Frejd (pg. 1, [0006]) and Hofstrom (Figure 2) teach that such polypeptides can be conjugated to chelators such as DOTA. The skilled artisan would particularly have a reasonable expectation of success using the method of Perols because Perols teaches attaching the chelator to amine groups on lysine residues and the protein N-terminus and the protein of SEQ ID NO: 4 has an N-terminus and five lysine residues. Additionally, Perols teaches preparing the affibody for this conjugation during a chemical synthesis process of making the affibody similar to the synthesis process taught by Frejd.
The skilled artisan would have been motivated to make this modification to provide a high stability and high affinity radionuclide chelating group such as DOTA to the HER2 binding affibody. Additionally, the skilled artisan would be motivated to make this modification because Lindberg suggests using derivatives of chelators such as polyamino-carboxylate chelators (such as DOTA) instead of peptide-based chelators in HER2 affibodies containing N-terminal HEHEHE tags.
Regarding claim 11, as described above, the combined teachings of Frejd, Hofstrom, and Lindberg render obvious the HER2 affibody of SEQ ID NO: 4 of claim 10. Additionally, Frejd teaches that HER2 binding affibodies can be modified with chelators such as DOTA (pg. 1, [0006]). Additionally, Hofstrom teaches attachment of a non-peptide bifunctional chelator to HER2 affibodies (Figure 2). Furthermore, Perols teaches conjugating a DOTA chelator to HER2 binding affibodies (pg. 1662-1663, Synthesis of DOTA-Conjugated Affibody Molecules). Additionally, Perols teaches radiolabeling the DOTA conjugated affibody with 111In (pg. 1663, paragraph 5). Given these teachings, for the reasons provided above, it would have been prima facie obvious to modify the HER2 affibody of Frejd, Hofstrom, and Lindberg with a bifunctional chelator. Furthermore, Perols teaches using the radiolabeled DOTA conjugated affibody for SPECT/CT imaging (Figure 9). Thus, the examiner interprets the product to be an imaging agent. Therefore, the combined teachings of Frejd, Hofstrom, Lindberg, and Perols render claim 11 obvious.
Regarding claim 12, Perols teaches radiolabeling the DOTA-conjugated HER2 binding affibody with 111In (pg. 1663, paragraph 5). The examiner interprets 111In to be a radioisotope. Therefore, the combined teachings of Frejd, Hofstrom, Lindberg, and Perols render claim 12 obvious.
Pertinent Art
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
As pertinent art, the examiner cites Fu (Fu, R.; et al., Chem. Med. Chem., 2018). Fu teaches strategies and applications of radiolabeled antibody fragments and affibodies (pg. 2466, Title and Abstract). Fu provides examples of several chemistries used by artisans in the field of radiopharmaceuticals to label proteins with radionuclides and bifunctional chelators (pg. 2470, Figure 2; pg. 2473, Figure 5; pg. 2474, Figure 6 and Scheme 9; and pg. 2476, Table 3). The examiner notes that this reference demonstrates that the skilled artisan in the field of radiopharmaceuticals is aware of and capable of multiple means of attaching bifunctional chelators to polypeptides such as affibodies.
As pertinent art, the examiner cites Liu (Liu, S.; et al, Bioconjugate Chem., 1997). Liu teaches radiolabeling peptides with 99mTc (pg. 621, Title). More specifically, Liu teaches three examples of means of labeling peptides with 99mTc (pg. 622, Figure 1; pg. 623, Chart 2; pg. 624, Chart 3; pg. 626, Chart 4; and pg. 623, Three Radiolabeling Approaches). In Charts 2, 3, and 4, Liu depicts a bifunctional chelator modified chelator binding 99mTc in the chelator group. The examiner notes that Liu teaches that 99mTc is capable of being bound by bifunctional chelators attached to polypeptides.
Conclusion
No claim is allowed.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Eric P Mosher whose telephone number is (571)272-3258. The examiner can normally be reached Monday-Friday 9am-5pm.
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, Sahana Kaup can be reached at (571) 272-6897. 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.
/E.P.M./Examiner, Art Unit 1612
/SAHANA S KAUP/Supervisory Primary Examiner, Art Unit 1612
Prosecution Insights