89Zr-CB307

**89Zr-CB307** is a radiolabeled (zirconium-89) version of CB307, a trispecific Humabody® engineered antibody fragment that simultaneously targets CD137, prostate-specific membrane antigen (PSMA), and human serum albumin (HSA) for imaging and biodistribution studies in cancer. The base molecule, CB307, is a first-in-class, half-life extended immunotherapeutic designed to provide potent CD137 agonism restricted to PSMA-high tumor microenvironments. CD137 (also known as 4-1BB) is a costimulatory receptor on T cells and NK cells; agonism of this receptor enhances T-cell cytotoxicity, proliferation, cytokine production, and survival. CB307 is designed to cluster CD137 on immune cells only in the presence of PSMA-expressing cancer cells, minimizing systemic toxicity and boosting antitumor immunity, particularly for PSMA-positive metastatic castration-resistant prostate cancer (mCRPC). Radiolabeling with 89Zr enables PET imaging for assessment of target engagement and biodistribution in early clinical studies[1][2][3][5].

Other names

89Zr CB307