Patent ID: 8337842

Claim:
A heterochimeric antibody, or fragment thereof, comprising, amino acid sequences of antibodies from a donor species of mammal and from a target species of mammal, wherein the donor species and the target species are different, comprising: a) a constant region sequence from a heavy chain and/or light chain identical to, or a conservative variant of, a sequence from the target species; and b) a variable domain sequence from a heavy chain and/or light chain, wherein said variable domain sequence comprises: i.) hypervariable region sequences comprising three complementarity determining regions (CDRs) as defined by Kabat, which are identical to, or a conservative variant of, CDRs from the donor species, and ii.) FR1, FR2, FR3, and FR4 framework sequences, wherein the FR1 and/or the FR4 sequence is identical to, or a conservative variant of, a FR1 and/or FR4 sequence from the target species, and the FR2 and FR3 sequences are identical to, or a conservative variant of, FR2 and FR3 sequences from the donor species; wherein said variable domain sequence comprises at least three contiguous non-CDR residues corresponding to residues from the target species and at least three contiguous non-CDR residues corresponding to residues from the donor species, wherein the heterochimeric antibody or fragment thereof, comprises a heavy chain and a light chain, and the CDRs are from the same donor antibody.