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. Election/Restrictions Applicant elects, without traverse, 1) a PD-L1 binding domain having six complementarity determining regions defined by non-degenerate SEQ ID NO: HC-CDR1: SEQ ID NO: 10, HC-CDR2: SEQ ID NO: 11, HC-CDR3: SEQ ID NO: 12, LC-CDR1: SEQ ID NO: 13, LC-CDR2: SEQ ID NO: 14, and LC-CDR3: SEQ ID NO: 15 ; 2) a CD28 binding domain having the heavy and light chain pair species corresponding to SEQ ID NO: 7 and SEQ ID NO: 8 ; 3) a linker that connects C-terminus of A to the N-terminus of the Fab heavy chain polypeptide; and 4) the multispecific antibody species described in claim 68 . The elected PD-L1 binding domain CDRs are present in the light and heavy chains of SEQ ID NOs: 17 and 16, respectively as recited in claims 58 and 63. The anti-PD-L1 Fab light and heavy chains of SEQ ID NOs: 16 and 17 are further present in the multispecific antibodies recited in claims 68-70 and 72-74. The elected orientation of antigen-binding domains also reads on a linker that connects the Fab heavy chain to the C-terminus of the scFv VH or VL chain as recited in claims 28 and 30. Thus claims 3, 9, 15, 28, 30, 36, 38, 41, 42, 43, 48, 53 58, 63, 68-70, and 72-74 (all claims) are examined on the merits in the present Office Action. Claim Interpretation Claims 68 – 70 recite a multispecific antibody comprising a Fab light chain comprising the amino acid sequence of SEQ ID NO: 20 and a Fab heavy chain comprising the amino acid sequence of SEQ ID NO: 21. However, the amino acid sequence of SEQ ID NO: 21 comprises an anti-CD27 scFv antibody, a linker, and an anti-PD-L1 Fab heavy chain. A Fab heavy chain thus cannot comprise the amino acid sequence of SEQ ID NO: 21 [see 35 USC 112(b) rejection below]. For the purposes of examination , claims 68-20 will be interpreted as a multispecific antibody comprising a Fab light chain of SEQ ID NO: 20 and a construct of SEQ ID NO: 21, wherein the construct comprises an anti-CD28 scFv, a linker, and an anti-PD-L1 Fab heavy chain. Similarly, claims 72-74 recite a multispecific antibody comprising a Fab heavy chain comprising the amino acid sequence of SEQ ID NO: 23 and a Fab light chain comprising the amino acid sequence of SEQ ID NO: 2 2 . However, the amino acid sequence of SEQ ID NO: 2 2 comprises an anti-CD27 scFv antibody, a linker, and an anti-PD-L1 Fab light chain. A Fab light chain thus cannot comprise the amino acid sequence of SEQ ID NO: 2 2 [see 35 USC 112(b) rejection below]. For the purposes of examination, the claims 72-74 will be interpreted as a multispecific antibody comprising a Fab heavy chain of SEQ ID NO: 23 and a construct of SEQ ID NO: 22, wherein the construct comprises an anti-CD28 scFv, a linker, and an anti-PD-L1 Fab light chain. Claim Rejections - 35 USC § 112 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. Claim s 41, 42, 58, 63, 68, 69, 70, 72, 73, and 74 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. Claims 41 and 42 are broadly drawn to multispecific antibodies having only the heavy chain or light chain CDRs, respectively, and thus less than six CDRs required for antigen binding by a conventional antibody or fragment thereof (in this case, a Fab fragment). Similarly, c laims 58 and 63 are broadly drawn to multispecific antibodies having only the heavy chain or light chain of the PD-L1 binding domain, respectively, and thus less than six CDRs required for antigen binding by a conventional antibody or fragment thereof (in this case, a Fab fragment). Further, the heavy and light chains of claims 58 and 63 each possess at least 90% identity to the recited sequences and can thus comprise random, undefined amino acid mutations that can potentially disrupt antigen binding. Claims 68-70 encompass multispecific antibodies comprising random, undefined amino acid mutations that can occur in the antigen-binding domains and linker region . The claims further encompass multispecific antibodies that can have a truncated framework regions at the N- terminal end of an antigen-binding domain. Similarly, claims 72-74 encompass multispecific antibodies comprising random, undefined amino acid mutations that can occur in the antigen-binding domains and linker region . The claims further encompass multispecific antibodies that can have a truncated framework regions at the N- terminal end of an antigen-binding domain. The guidelines for the Examination of Patent Applications Under the 35 U.S.C. 112, § 1 "Written Description" Requirement make clear that if a claimed genus does not show actual reduction to practice for a representative number of species, then the Requirement may be alternatively met by reduction to drawings, or by disclosure of relevant, identifying characteristics, i.e., structure or other physical and or chemical properties, by functional characteristics coupled with a known or disclosed correlation between function and structure, or by a combination of such identifying characteristics, sufficient to show the applicant was in possession of the genus ( MPEP 2163). In The Regents of the University of California v. Eli Lilly (43 USPQ2d 1398-1412) 19 F. 3d 1559, the court held that disclosure of a single member of a genus (rat insulin) did not provide adequate written support for the claimed genus (all mammalian insulins). In this same case, the court also noted: “A definition by function, as we have previously indicated, does not suffice to define the genus because it is only an indication of what the gene does, rather than what it is. See Fiers , 984 F.2d at 1169-71, 25 USPQ2d at 1605-06 (discussing Amgen). It is only a definition of a useful result rather than a definition of what achieves that result. Many such genes may achieve that result. The description requirement of the patent statute requires a description of an invention, not an indication of a result that one might achieve if one made that invention. See In re Wilder, 736 F.2d 1516, 1521, 222 USPQ 369, 372-73 (Fed. Cir. 1984) (affirming rejection because the specification does “little more than outlin [e] goals appellants hope the claimed invention achieves and the problems the invention will hopefully ameliorate."). Accordingly, naming a type of material generally known to exist, in the absence of knowledge as to what that material consists of, is not a description of that material.” The court has further stated that “Adequate written description requires a precise definition, such as by structure, formula, chemical name or physical properties, not a mere wish or plan for obtaining the claimed chemical invention.” Id. at 1566, 43 USPQ2d at 1404 (quoting at 1171, 25 USPQ2d at 1606). Also see (CAFC 2002). Enzo- Biochem v. Gen-Probe Fiers , 984 F.2d 01-1230. Claims 41 and 42 are broadly drawn to multispecific antibodies having only the heavy chain or light chain CDRs, respectively, and thus less than six CDRs required for antigen binding by a conventional antibody or fragment thereof (in this case, a Fab fragment). Similarly, c laims 58 and 63 are broadly drawn to multispecific antibodies having only the heavy chain or light chain of the PD-L1 binding domain, respectively (see Table 6 of the Specification) , and thus less than six CDRs required for antigen binding by a conventional antibody or fragment thereof (in this case, a Fab fragment). Further, the heavy and light chains recited in claims 58 and 63 each possess at least 90% identity to the recited sequences and can thus comprise random, undefined amino acid mutations that can potentially disrupt antigen binding. It is well-known in the art that, in order to bind antigen, a conventional antibody or antigen-binding fragment must have six complementarity defining regions (CDRs) (Janeway, see selection, in particular section 3-6). As such, the structure of a PD-L1 binding domain derived from a Fab fragment having less than six CDRs is not correlated with the function of binding to antigen. Further, the claimed light and heavy chains of the PD-L1 binding domain represent partially defined structure s in which at most 10% of the recited amino acid sequence can vary. Such variation can occur, for example, by amino acid substitution, deletion, or insertion and be present in the CDR sequences . However, there is no guidance provided in the specification about which specific amino acids mutations can made in the claimed light or heavy chain s of the PD-L1 binding domain such that the ability of the multispecific antibody to bind to PD-L1 is retained. Indeed, it is well-known that amino acid substitutions in the antibody in the CDR domains can eliminate binding activity (see, e.g. Piche-Nicholas et al, see in particular, Abstract; Colman, see entire document particularly Page 33, Col. 2; and Rudikoff et al, see Abstract) . The level of skill and knowledge in the art is such that one of ordinary skill would not be able to readily identify without further testing which amino acid mutations can be made in the light or heavy chain s of the PD-L1 binding domain, particularly in the CDR sequences, such that the ability of the multispecific antibody to target PD-L1 is retained. Similarly, claims 68 and 72 encompass a multispecific antibody comprising an anti-PD-L1 Fab light or heavy chain having at least 90% sequence identity to SEQ ID NO: 20 or 23, respectively (see Table 8 of the Specification) , and a construct comprising, from the N-to-C terminus, an anti-CD28 scFv, a linker, and an anti-PD-L1 Fab heavy or light chain, respectively, wherein the construct has at least 90% sequence identity to SEQ ID NOs: 21 or 22 (see Table 8 of the Specification) . Thus, claims 68 and 72 encompass multispecific antibody variants having random, undefined amino acid mutations that can occur in the CD28 and PD-L1 antigen-binding domains (including in the CDR sequences) and/or linker sequences. As discussed above, amino acid mutations in the CDR domains of an antibody can negatively impact binding activity. However, there is no guidance provided in the specification about which specific amino acid mutations can be made in the CD28 and PD-L1 antigen binding domains of the claimed multispecific antibodies -particularly in the CDR sequences-without disrupting the binding affinity for the target antigens . Additionally, linkers in recombinant fusion proteins not only connect functional domains together but also significantly affect the structural stability, biological activity, expression yield, and pharmacokinetic profile of the protein (see, e.g. Chen et al, Abstract, Section 5: Functionality of Linkers in Fusion Proteins, and Section 6: Summary and Perspective) . As such, random amino acid mutations made in the linker sequence of the claimed multispecific antibodies can also impair antigen binding. However, there is insufficient guidance provided in the specification and prior art about which specific amino acid residues in the linker sequence are amenable to random mutagenesis such that the ability of the claimed multispecific antibodies to target CD28 and PD-L1 is maintained. Without further guidance, artisans would have to perform additional screening and testing to identify multispecific antibody variants encompassed by the claimed genus having the functional property of binding to target antigens CD28 and PD-L1. Claims 69 and 73 encompass a multispecific antibody comprising an anti-PD-L1 Fab light or heavy chain having at least 200 consecutive amino acid resides of SEQ ID NO: 20 (total length: 213 aa) or SEQ ID NO: 23 (total length: 226 aa) , respectively, and a construct comprising, from the N-to-C terminus, an anti-CD28 scFv, a linker, and an anti-PD-L1 Fab heavy or light chain, respectively, wherein the construct has at least 450 consecutive amino acid residues of SEQ ID NO: 21 (total length: 473 aa) or SEQ ID NO: 22 (total length: 460 aa) . Thus, claims 69 and 70 encompass multispecific antibody variants having a truncated amino acid sequence . For example, the multispecific antibody can have a shortened framework region at the N terminal end of an antigen- binding domain. The framework regions of an antibody act as a scaffold that holds the six CDR loops in the correct conformation to bind antigen ( Creative Biolabs, see “Difference between CDRs and Framework Regions (FRs)” section). As such, deletions or structural changes in the framework regions of an antigen-binding domain can disrupt the structural integrity and impair binding affinity . However, neither the specification or prior art provides any guidance for the predictable identification of functional antibodies comprising truncated framework region s . Without further guidance, artisans would have to perform additional screening and testing to identify multispecific antibody variants encompassed by the claimed genus having the functional property of binding to target antigens CD28 and PD-L1. Lastly , claims 70 and 74 encompass multispecific antibodies comprising an anti-PD-L1 Fab light or heavy chain having at least 90% sequence identity to at least 200 consecutive amino acid residues of SEQ ID NO: 20 or 23, respectively, and a construct comprising, from the N-to-C terminus, an anti-CD28 scFv, a linker, and an anti-PD-L1 Fab heavy or light chain, respectively, wherein the construct has at least 90% sequence identity to at least 450 consecutive amino acid residues of SEQ ID NOs: 21 or 22. Thus, claims 70 and 74 encompass multispecific antibody variants having not only a truncated amino acid sequence, wherein the framework region at the N-terminal end of an antigen-binding domain is shortened, but also random, undefined mutations. As discussed earlier, neither the specification or prior art provides any guidance for the predictable identification of functional antibodies comprising truncated framework regions and random amino acid mutations. Without further guidance, artisans would have to perform additional screening and testing to identify multispecific antibody variants encompassed by the claimed genus having the functional property of binding to target antigens CD28 and PD-L1. Therefore, the claimed genera of multispecific antibodies lacks adequate written description because there does not appear to be any correlation between the structure of the claimed genera of multispecific antibodies and the function of binding to the target antigens CD28 and PD-L1 in a subject. Thus, one of ordinary skill in the art would reasonably conclude that the applicant was not in possession of the full breadth of the claimed genera of multispecific antibodies at the time the instant application was filed. Scope of Enablement Claims 41, 42, 58, 63, 68, 69, 70, 72, 73, and 74 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA), first paragraph, because the specification, while being enabling for a multispecific antibody comprising a fully defined PD-L1 - binding domain , CD28-binding domain, and linker region , does not reasonably provide enablement for multispecific antibody variants comprising a) random, undefined amino acid mutations in the antigen-binding domains (particularly in the CDRs) and/or linker region; b) antigen-binding domains having a single variable domain and thus less than six CDRs; and/or c) truncated framework regions. The specification does not enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make or use the invention commensurate in scope with these claims. The nature of the invention relates multispecific CD28 x PD-L1 antibodies that can be used to increase the T cell cytotoxicity of T cell engagers against tumor cells (see Para. 0003 and Para. 0044-0050 of Specification). Claims 41 and 42 are broadly drawn to multispecific antibodies having only the heavy chain or light chain CDRs, respectively, and thus less than six CDRs required for antigen binding by a conventional antibody or fragment thereof (in this case, a Fab fragment). Similarly, c laims 58 and 63 are broadly drawn to multispecific antibodies having only the heavy chain or light chain of the PD-L1 binding domain, respectively, and thus less than six CDRs required for antigen binding by a conventional antibody or fragment thereof (in this case, a Fab fragment). Further, the heavy and light chains of claims 58 and 63 e ach possess at least 90% identity to the recited sequences and can thus comprise random, undefined amino acid mutations that can potentially disrupt antigen binding. The specification discloses several multispecific anti-CD28 x PD-L1 antibodies , including AB-1 to AB- 8 (Table 8, Pages 89-94) . Clones AB-1 and AB-2 comprise the recited anti-CD28 scFv domain as well as the elected PD-L1 binding domain but in different orientations. It was demonstrated that multispecific antibodies had binding affinity for the target antigens CD28 and PD-L1 (Examples 1- 5 , Figures 8A-8B, and Tables 18 and 19). Further, the anti-CD28 x PD-L1 multispecific antibodies enhanced immune activation and tumor cell killing when used in combination with bispecific T cell engager such as anti-TROP2 x CD3 or anti-PSMA x CD3 (Examples 6-8). However, t here is no evidence provided in the specification that 1) a multispecific antibody comprising a PD-L1 binding domain having less than six CDRs (i.e. heavy chain only or light chain only) is capable of binding to PD-L1 or 2) random, undefined amino acid mutations can be made in claimed heavy and lights chains of the PD-L1 binding domains without negatively impacting binding affinity for PD-L1. Indeed, s uch variation can be caused by different types of amino acid mutations –e.g. substitutions, deletions, and insertions—and can occur in the CDRs of the heavy and light chains; yet the re is in sufficient guidance on which amino acid residues, particularly in the CDR sequences, of the claimed heavy and light chain v ar iants ar e amenable to mutagenesis without disrupting antigen bindin g. It is well-known in the art that, in order to bind antigen, a conventional antibody or antigen-binding fragment must have six complementarity defining regions (CDRs) (Janeway, see selection, in particular section 3-6). As such, a multispecific antibody comprising a PD-L1 domain defined by less than six CDRs ( i.e. heavy chain only or light chain only ) encompassed by claims 58 and 63 is not reasonably expected to be capable of binding to the target antigen PD-L1. Further, amino acid mutations in the CDR domains of an antibody can negatively impact binding activity (see, e.g. Piche-Nicholas et al, see in particular, Abstract ; Colman, see entire document particularly Page 33, Col. 2; and Rudikoff et al, see Abstract) . Thus, even a single amino acid substitution at a critical residue can significantly reduce or abolish binding to a target antigen. Accordingly, the effect of amino acid mutations on binding affinity is not readily predictable. Without further evidence, artisans would not reasonably expect multispecific antibodies comprising random, undefined amino acid mutations in the heavy and light chains of the PD-L1 binding domain to be capable of binding to PD-L1. Similarly, claims 68 and 72 encompass a multispecific antibody comprising a n anti-PD-L1 Fab light or heavy chain having at least 90% sequence identity to SEQ ID NO: 20 or 23, respectively, and a construct comprising, from the N-to-C terminus , an anti-CD28 scFv, a linker , and an anti-PD-L1 Fab heavy or light chain, respectively, wherein the construct has at least 90% sequence identity to SEQ ID NOs: 21 or 22 . Thus, claims 68 and 72 encompass multispecific antibody variants having random, undefined amino acid mutations that can occur in the CD28 and PD-L1 antigen-binding domains (including in the CDR sequences) and/or linker sequences. As discussed above, amino acid mutations in the CDR domains of an antibody can negatively impact binding activity . Further, there is no evidence or guidance provided in the specification about which specific amino acid mutations can be made in the CD28 and PD-L1 antigen binding domains -particularly in the CDR sequences-without negatively impacting the ability of the multispecific antibody to bind to CD28 and PD-L1. Additionally, linkers in recombinant fusion proteins not only connect functional domains together but also significantly affect the structural stability, biological activity, expression yield , and pharmacokinetic profile of the protein (see, e.g. Chen et al, Abstract, Section 5: Functionality of Linkers in Fusion Proteins, and Section 6: Summary and Perspective). As such, random amino acid mutations made in the linker sequence of the claimed multispecific antibodies can also potentially have a negative impact on binding affinity. However , t here does not appear to be any guidance provided in the specification or prior art about which specific amino acid residues in the linker sequence are amenable to random mutagenesis such that the ability of the claimed multispecific antibodies to target CD28 and PD-L1 is maintained. Thus, w ithout further evidence, artisans would not reasonably expect multispecific antibodies comprising random, undefined amino acid mutations in the antigen-binding domains and/or linker region to bind to be capable of binding to CD28 and PD-L1. Claims 69 and 73 encompass a multispecific antibody comprising an anti-PD-L1 Fab light or heavy chain having at least 200 consecutive amino acid resides of SEQ ID NO: 20 (total length: 21 3 aa) or SEQ ID NO: 23 (total length: 2 2 6 aa) , respectively, and a construct comprising, from the N-to-C terminus, an anti-CD28 scFv, a linker, and an anti-PD-L1 Fab heavy or light chain, respectively, wherein the construct has at least 450 consecutive amino acid residues of SEQ ID NO: 21 (total length: 473 aa) or SEQ ID NO: 22 (total length: 460 aa) . Thus, claims 69 and 70 encompass multispecific antibody variants having a truncated amino acid sequence . For example, the multispecific antibody can have a shortened framework region at the N terminal end of an antigen-binding domain . (Creative Biolabs, see “Difference between CDRs and Framework Regions (FRs)” section). As such, deletions or structural changes in the framework regions of an antigen-binding domain can disrupt the structural integrity and impair binding affinity. However, neither the specification or prior art provides any evidence that the claimed multispecific antibodies comprising a truncated N-terminal framework region in the CD28 or PD-L1 binding domain maintain binding affinity for the target antigen. Without further evidence, artisans would not reasonably expect a multispecific antibody comprising an antigen-binding domain having a truncated framework region to bind to the target antigen CD28 or PD-L1. Similarly, claims 70 and 74 encompass multispecific antibodies comprising an anti-PD-L1 Fab light or heavy chain having at least 90% sequence identity to at least 200 consecutive amino acid residues of SEQ ID NO: 20 or 23, respectively, and a construct comprising, from the N-to-C terminus , an anti-CD28 scFv, a linker , and an anti-PD-L1 Fab heavy or light chain, respectively, wherein the construct has at least 90% sequence identity to at least 450 consecutive amino acid residues of SEQ ID NOs: 21 or 22 . Thus, claims 70 and 74 encompass multispecific antibody variants having not only a truncated amino acid sequence — wherein the framework region at the N-terminal end of an antigen-binding domain is shortened — but also random, undefined mutations. As discussed earlier, artisans would not reasonably expect a multispecific antibody comprising an antigen-binding domain having a truncated framework region and random, undefined amino acid mutations-particularly in the CDR sequences- to bind to the target antigen CD28 or PD-L1 absent of evidence provided to the contrary. A person of ordinary skill in the art at the time of filing would have had experience in antibody engineering, including CDR mutagenesis and screening techniques. Even at this high level of skill, however, the effect of randomly mutating amino acids in the CDRs of an antigen-binding domain on affinity for a target antigen cannot be readily predicted without additional testing. In Amgen Inc. v. Sanofi, Aventisub LLC, 987 F.3d 1080 (Fed. Cir. 2021), which the Supreme Court affirmed, the Federal Circuit relied on evidence showing that the scope of the claims encompassed millions of antibodies and that it was necessary to screen each candidate antibody in order to determine whether it met the functional limitations of the claim. Id. at 1088. Consequently, the Federal Circuit concluded that there was a lack of enablement (MPEP 2164.06). Similarly, the binding affinity of a multispecific antibody having amino acid mutations in the linker region connecting the CD28 and PD-L1 binding domains or truncated framework regions also cannot be readily predicted without further testing and evaluation. Thus, the level of skill does not obviate the need for substantial experimentation across the full scope of the claimed genera especially given that there is no guidance provided in the specification or prior art on which amino acid mutations can be made in the CD28 and PD-L1 antigen binding domains and/or linker regions that will result in a functional variant that still binds to the target antigen s. Therefore, the specification is not enabling over the full scope of the claims. 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 appl icant regards as his invention. Claim s 68-70 and 72-74 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 68 recites a multispecific antibody “ wherein the linker connects the Fab heavy chain polypeptide to the C-terminus of the scFv light chain variable domain and wherein the Fab light chain polypeptide comprises an amino acid sequence that has at least 90% sequence identity to the amino acid sequence according to SEQ ID NO: 20, and an amino acid sequence of the Fab heavy chain polypeptide that is connected to the C-terminus of the scFv light chain variable domain comprises an amino acid sequence that has at least 90% sequence identity to the amino acid sequence according to SEQ ID NO: 21 . ” As presently written, it is unclear if the multispecific antibody comprises: the Fab light chain of SEQ ID NO: 20 and the amino acid sequence of SEQ ID NO: 21, which comprises an anti-CD27 scFv antibody, a linker, and an anti-PD-L1 Fab heavy chain (see Table 8 of the Specification) ; or the Fab light chain of SEQ ID NO: 20 and the Fab heavy chain present in the amino acid sequence of SEQ ID NO: 21. Claims 69 and 70 have a similar construction and are thus likewise rejected for indefiniteness . It is noted that the amino acid sequence of SEQ ID NO: 21 encompasses an anti-scFv antibody, a linker, and an anti-PD-L1 Fab heavy chain. As such, a Fab heavy chain cannot comprise an amino acid sequence of SEQ ID NO: 21. As such, the claim s do not clearly set forth the metes and bounds of the patent protection desired. Claim 72 recites a multispecific antibody “ wherein the linker connects the Fab light chain polypeptide to the C-terminus of the scFv light chain variable domain and wherein the Fab heavy chain polypeptide comprises an amino acid sequence that has at least 90% sequence identity to the amino acid sequence according to SEQ ID NO: 23, and an amino acid sequence of the Fab light chain polypeptide that is connected to the C-terminus of the scFv light chain variable domain comprises an amino acid sequence that has at least 90% sequence identity to the amino acid sequence according to SEQ ID NO: 22 . ” As presently written, it is unclear if the multispecific antibody comprises: the Fab heavy chain of SEQ ID NO: 23 and the amino acid sequence of SEQ ID NO: 22, which comprises an anti-CD27 scFv antibody, a linker, and an anti-PD-L1 Fab light chain (see Table 8 of the Specification) ; or the Fab heavy chain of SEQ ID NO: 23 and the Fab light chain present in the amino acid sequence of SEQ ID NO: 22. Claims 73 and 74 have a similar construction and are thus likewise rejected for indefiniteness . It is noted that the amino acid sequence of SEQ ID NO: 22 encompasses an anti-scFv antibody, a linker, and an anti-PD-L1 Fab light chain. As such, a Fab light chain cannot comprise an amino acid sequence of SEQ ID NO: 22. As such, the claim s do not clearly set forth the metes and bounds of the patent protection desired. 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. 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 3, 9, 15, 28, 30, 36, 38 , 43, 48, and 53 are rejected under 35 U.S.C. 103 as being unpatentable over Ellmark et al (US20180118841A1), hereinafter Ellmark , in view of Rader (Rader, Christoph. "Overview on concepts and applications of Fab antibody fragments." Current protocols in protein science 55.1 (2009): 6-9), Correnti et al ( Correnti , Colin E et al. “Simultaneous multiple interaction T-cell engaging (SMITE) bispecific antibodies overcome bispecific T-cell engager ( BiTE ) resistance via CD28 co-stimulation.” Leukemia vol. 32,5 (2018): 1239-1243. doi:10.1038/s41375-018-0014-3), hereinafter Correnti , and Georges et al ( US20200199234A1 , published 06/25/2020 prior to the date of the provisional application filed 10/30/2020 and having a different inventive entity ), hereinafter Georges. Ellmark discloses bispecific antibodies comprising first and second antigen binding domains (B1 and B2) capable of binding to different T cell targets (Abstract). CD28 is listed as an exemplary T cell target; as such, one of the binding domains in the bispecific antibody is an CD28 binding domain. Bispecific antibodies targeting two different T cell targets have the potential to specifically activate the immune system in locations where both targets are over-expressed (Para. 0011). The net effects of the bispecific antibodies targeting two T cell receptors thus include 1) a higher degree of immune activation compared to monospecific antibodies, 2) a higher degree of induction of ADCC compared to monospecific binders in combination, and 3) more directed/localized immune activation, which increases the therapeutic window and minimizes toxic side effects (Para. 0013). The B1 and/or B2 antigen-binding domains can be an intact IgG, scFv, Fab, and/or single domain antibody (Para. 0032). In exemplary embodiments, the bispecific antibody is an IgG-scFv format, wherein B1 is an intact IgG and B2 is an scFv attached to the N-terminus of a light or heavy chain of the IgG, or vice versa (Para. 0038). The IgG-scFv can be either in the VH-VL or VL-VH orientation (Para. 0047). As such, either the VH or VL chain of scFv can be attached to the N-terminus of the heavy or light chain of IgG. The B1 and B2 antigen-binding domains (e.g. IgG and scFv) can be joined via a polypeptide linker rich in glycine for flexibility and serine for solubility such as a linker having the amino acid sequence of SEQ ID NO: 144 (GGGGSGGGGSGGGGS), corresponding to SEQ ID NO: 18 of the instant claims (Para. 0048-0049) The polypeptide linker of SEQ ID NO: 4 has the format (GGGGS)n (SEQ ID NO: 60 of the instant claims), wherein n is 3. Ellmark does not specifically teach that 1) the bispecific antibody is a Fab-scFv (or scFv-Fab) format, wherein the scFv is attached to the N-terminus of the light or heavy chain of the Fab fragment; 2) the different T cell targets are CD28 and PD-L1, or 3) the CD28 binding domain has the CDRs of SEQ ID NOs: 1-6 ; the VH/VL chains of SEQ ID NOs: 7 and 8; and the full-length amino acid sequence of SEQ ID NO: 9, wherein the linker (G4S) 3 is present between the VH and VL chains (see Table 3 of the Specification). However, Rader teaches that Fab fragments are superior to IgG due to their higher mobility and tissue penetration capability, reduced circulatory half-life, ability to bind antigen monovalently without mediating antibody effector functions, and lower immunogenicity (see Introduction). Correnti teaches that T-cell coactivation with a PD-L1/CD28 bispecific antibody enhances T-cell activity against PD-L1 positive cancer cells, particularly when paired with a CD3-based bispecific T cell engager ( BiTE ), and overcomes PD-L1 mediated resistance while minimizing toxic off-target effects (see last paragraph on Page 3 to first two paragraphs on Page 4). Georges teaches an anti-CD28 antigen binding molecule comprising the VH chain having the amino acid sequence of SEQ ID NO: 42 and a VL chain having the amino acid sequence of SEQ ID NO: 27 (see Para. 0771) . The VH chain of SEQ ID NO: 42 corresponds to SEQ ID NO: 7 of the instant claims and fully comprises the CDRs of SEQ ID NOs: 1-3 recited in the instant claims; and the VL chain of SEQ ID NO: 27 corresponds to SEQ ID NO: 8 of the instant claims and fully comprises the CDRs of SEQ ID NOs: 4-6 recited in the instant claims. The antigen binding molecule can be an antibody or fragment thereof such as a single chain variable fragment (scFv) wherein the VH and VL chain s are connected via a short linker peptide of 10 to 25 amino acids (Para. 0166-0168, 0176-0177, and 0182). Several peptide linkers are contemplated including the linker (G4S) 3 (SEQ ID NO:151) (Para. 0243 and 0245). Taken together, Georges renders obvious the anti-CD28 binding domain present in the multispecific antibodies of the instant claims, wherein the VH and VL chains of the scFv antibody are connected by the peptide linker (G4S) 3 to yield SEQ ID NO: 9 of the instant claims. It would have been obvious to one of ordinary skill in the art to modify the IgG-scFv bispecific antibody such that 1) the IgG arm is replaced with a Fab fragment, wherein the VH or VL of the scFv is attached to the N-terminus of the Fab heavy chain via the linker (G4S) 3 (GGGGSGGGGSGGGGS) ; 2) the T cell targets are CD28 and PD-L1; and 3) the CD28 binding domain is substituted by that disclosed by Georges comprising the VH and VL chains of SEQ ID NOs: 42 and 72, respectively (corresponding to SEQ ID NOs: 7 and 8 of the instant claims) , wherein the VH and VL chains are connected via a (G4S) 3 linker. One of ordinary skill in the art would have been motivated to do so since Fab fragments have several advantages over full-length IgG, including increased tissue penetration, reduced circulatory half-life, lower immunogenicity, and ability to target antigen monovalently without triggering antibody effector functions as taught by Rader. Moreover , a PD-L1/CD28 bispecific antibody can enhance T-cell activity against PD-L1 positive cancer cells, particularly when paired with a CD3-based BiTE , and overcome PD-L1 mediated tumor resistance while minimizing toxic off-target effects as taught by Correnti . Additionally, it would have been obvious to artisans to substitute CD28-binding domain disclosed by Ellmark with that disclosed by Georges since they have the same function and can be used for the same purpose. An express suggestion to substitute one equivalent component or process for another is not necessary to render such substitution obvious. In re Fout , 675 F.2d 297, 213USPQ 532 (CCPA 1982). Lastly, the binding domains against targets CD28 and PD-L1 can be formatted interchangeably (e.g. scFv targets CD28 and Fab targets PD-L1, or vice versa). Therefore, one of ordinary skill in the art would reasonably expect a scFv-Fab bispecific antibody that binds to the T cell targets CD28 and PD-L1 can effectively treat cancer in a subject. Claims 41, 42, 58, 63, 68, 69, 70, 72, 73, and 74 are rejected under 35 U.S.C. 103 as being unpatentable over Ellmark in view of Rader , Correnti and Georges, as applied to claims 3, 9, 15, 28, 30, 36, 38, 43, 48, and 53 above, and further in view of Cardarelli et al ( US20180179282A1 ), hereinafter Cardarelli, and Chen et al ( Chen, Xiaoying et al. “Fusion protein linkers: property, design and functionality.” Advanced drug delivery reviews vol. 65,10 (2013): 1357-69. doi:10.1016/j.addr.2012.09.039 ), hereinafter Chen. The combined teachings of Ellmark in view of Rader, Correnti , and Georges disclose an scFv-Fab bispecific antibody that binds to the T cell targets CD28 and PD-L1, wherein a) the CD28 binding domain has VH and VL chains corresponding to the amino acid sequences of SEQ ID NOs: 7 and 8 of the instant claims and connected via a (G4S) 3 linker; and b) the VH or VL chain of the scFv is connected to the N-terminus of the Fab heavy chain via a (G4S) 3 linker. However, the teachings of the Ellmark in view of Rader, Correnti , and Georges differ from the instantly claimed invention in that it is not specifically taught that the PD-L1 binding domain has the structure recited in the instant claims nor is it taught that the antigen binding domains of the multispecific antibody are joined by the shorter glycine-serine rich linker GGGGS [or G4S) 1 ] [Note, the multispecific Ab constructs of SEQ ID NOs: 21 and 22 recited in the instant claims have the ( G4S) 1 between antigen-binding domains, see Table 8 of the Specification]. However, Cardarelli teaches an anti-PD-L1 antibody comprising the light chain having the amino acid sequence of SEQ ID NO: 7 and a heavy chain having the amino acid sequence of SEQ ID NO: 8 (Para. 0072). The light chain of SEQ ID NO: 7 corresponds to SEQ ID NO: 16 or 20 of the instant claims and fully comprises the CDRs of SEQ ID NOs: 13-15 of the instant claims. The heavy chain of SEQ ID NO: 8 corresponds to the amino acid sequence of SEQ ID NO: 17 or 23 of the instant claims and fully comprises the CDRs of SEQ ID NO: 10-12 of the instant claims. Chen teaches that the most commonly used flexible linkers in multi-domain fusion proteins have sequences consisting primarily of stretches of Gly and Ser residues , particularly (G4S ) n . The length of the GS linker can be optimized to achieve appropriate separation of the functional domains, or to maintain necessary inter-domain interactions , b y adjusting the copy number “n” . In particular, the flexible GGGGS linker [(G4S ) n = 1 ] has been shown to improve the biological activity of fusion proteins (see Section 3, 3. 1 and Table 3). It would have been obvious to one of ordinary skill in the art to modify the bispecific CD28 x PD-L1 scFv-Fab antibody taught by combined teachings of the prior art such that the PD-L1 binding domain is substituted with that disclosed by Cardarelli comprising the VH and VL chains of SEQ ID NOs: 42 and 72, respectively . One of ordinary skill in the art would have been motivated to do so since they have the same function and can be used for the same purpose. An express suggestion to substitute one equivalent component or process for another is not necessary to render such substitution obvious. In re Fout , 675 F.2d 297, 213USPQ 532 (CCPA 1982). Further the length of a glycine-serine rich linker joining the functional domains of the multispecific antibody can be determined by routine experimentation and thus encompass specific embodiments of the claimed invention wherein the GS linker is the shorter but flexible GGGGS peptide . Similarly, the orientation of the antigen-binding domains as well as the VH and VL chains present in the scFv can also be determined by routine experimentation. "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955 ). The combined teachings of the prior art render obvious the multispecific antibody of the instant claims comprising the recited anti-CD28 scFv and anti-PD-L1 Fab domains, wherein the antigen-binding domains are joined by the ( G4S) 1 linker . Therefore, one of ordinary skill in the art would reasonably expect the scFv-Fab bispecific antibody disclosed by the combined teachings of the prior art to effectively treat cancer in a subject. 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