Human serum albumin linkers and conjugates thereof

Abstract

Disclosed is a human serum albumin (HSA) linker and HSA linker with binding, diagnostic, and therapeutic agents conjugated thereto. Also disclosed is a conjugate in which the HSA linker is covalently bonded to amino and carboxy terminal binding moieties that are first and second single-chain Fv molecules (scFvs). Exemplified conjugates are useful, e.g., in reducing tumor cell proliferation, e.g., for therapeutic therapeutic applications. Also disclosed are methods and kits for the diagnostic and therapeutic application of an HSA linker conjugate.

1 .- 36 . (canceled) 
     
     
         37 . A conjugate comprising a human serum albumin (HSA) linker having an amino terminus and a carboxy terminus, said HSA linker comprising an amino acid sequence having at least 95% sequence identity to the sequence set forth in SEQ ID NO: 1 and comprising a first binding moiety bonded to the amino terminus of said HSA linker and a second binding moiety bonded to the carboxy terminus of said HSA linker, wherein said first binding moiety specifically binds ErbB3 with a dissociation constant (K d ) of about 16 nM, as determined by surface plasmon resonance, and said second binding moiety specifically binds ErbB2 with a K d  of about 0.3 nM, as determined by surface plasmon resonance. 
     
     
         38 . The conjugate of  claim 37 , wherein the HSA linker further comprises a peptide connector comprising 2 to 20 amino acid residues at the amino or carboxy terminus of said HSA linker, wherein said peptide connector covalently joins said HSA linker to said first or second binding moiety. 
     
     
         39 . A composition comprising the conjugate of  claim 37  admixed with a pharmaceutically acceptable carrier, excipient, or diluent. 
     
     
         40 . The composition of  claim 39  in a solution comprising 25 mg/mL of the conjugate. 
     
     
         41 . The conjugate of  claim 37 , wherein said first binding moiety is a single chain variable fragment (scFv) comprising the amino acid sequence of SEQ ID NO: 26 and said second binding moiety is an scFv comprising the amino acid sequence of SEQ ID NO: 27. 
     
     
         42 . The conjugate of  claim 38 , wherein said HSA linker comprises a peptide connector of 2 to 20 amino acid residues between said first binding moiety and said HSA linker and a peptide connector of 2 to 20 amino acid residues between said second binding moiety and said HSA linker. 
     
     
         43 . The conjugate of  claim 37 , wherein said HSA linker comprises a serine residue at position 34 of SEQ ID NO: 1 and a glutamine residue at position 503 of SEQ ID NO: 1. 
     
     
         44 . The conjugate of  claim 37 , wherein said HSA linker comprises the amino acid sequence of SEQ ID NO: 1. 
     
     
         45 . The conjugate of  claim 37 , wherein each of said first and second binding moieties is an scFv. 
     
     
         46 . The conjugate of  claim 45 , wherein each said scFv is human or humanized. 
     
     
         47 . The conjugate of  claim 37 , wherein said conjugate exhibits an in vivo half-life of greater than 8 hours. 
     
     
         48 . The conjugate of  claim 37 , wherein said HSA linker comprises amino acid residues 25-44 and amino acid residues 494-513 of SEQ ID NO:1. 
     
     
         49 . The conjugate of  claim 48 , wherein said HSA linker comprises amino acid residues 25-70 and amino acid residues 450-513 of SEQ ID NO:1. 
     
     
         50 . The conjugate of  claim 49 , wherein said HSA linker comprises amino acid residues 15-100 and amino acid residues 400-520 of SEQ ID NO:1. 
     
     
         51 . The conjugate of  claim 50 , wherein said HSA linker comprises amino acid residues 10-200 and amino acid residues 300-575 of SEQ ID NO:1. 
     
     
         52 . The conjugate of  claim 51 , wherein said HSA linker comprises amino acid residues 5-250 and amino acid residues 275-580 of SEQ ID NO:1. 
     
     
         53 . The conjugate of  claim 37 , wherein said conjugate exhibits the ability to bind both ErbB2 and ErbB3 before and after incubation in human serum at 37° C. for 120 hours as measured by enzyme-linked immunosorbent assay (ELISA). 
     
     
         54 . A kit comprising the conjugate of  claim 37  in a package with instructions for administering said conjugate to a patient.