Patent ID: 8703132

Claim:
A bispecific, tetravalent antigen binding protein, comprising: a) a first heavy chain of a first antibody, wherein said first antibody specifically binds to a first antigen, and wherein said first heavy chain is fused through its C-terminus to the N-terminus of a moiety comprising VH-CH1 domains of said first antibody; b) two light chains of said first antibody of a); c) a second heavy chain of a second antibody, wherein said second antibody specifically binds to a second antigen, wherein said second heavy chain is fused through its C-terminus to the N-terminus of a moiety comprising VH-CL domains of said second antibody, and wherein the CH1 domain of said second heavy chain is replaced by the CL domain of said second antibody; and d) two second light chains of said second antibody of c), wherein the CL domain of each of said second light chains is replaced by the CH1 domain of said second antibody.