Abstract: Involved is an isolated antigen binding protein, being capable of binding CCR8 derived from a primate animal. Further involved are a pharmaceutical composition comprising the antigen binding protein, and an application of the antigen binding protein and/or the pharmaceutical composition in the prevention and/or treatment of a tumor or a cancer.

Abstract: Provided are a bispecific antibody and use thereof. The bispecific antibody comprises a B7-H4-targeting antigen-binding domain and a 4-1BB-targeting antigen-binding domain. The bispecific antibody has one or two or three sites for binding to 4-1BB, along with a novel fully human B7-H4 antibody. The bispecific antibody specifically binds to tumor cells by targeting B7-H4, reducing toxicity induced by 4-1BB activation. In addition, the bispecific antibody of the present invention comprises a human Fc fragment, and thus retains the binding of Fc to FcRn and has a longer half-life.