Definition

A half-life extended (HLE), bispecific T-cell engager (BiTE) antibody composed of two single-chain variable fragments (scFv), one directed against the tumor-associated antigen (TAA) human prostate-specific membrane antigen (PSMA), fused to one that is directed against the CD3 antigen found on T lymphocytes, with potential immunostimulating and antineoplastic activities. Upon administration acapatamab binds to both CD3 on cytotoxic T lymphocytes (CTLs) and PSMA found on PSMA-expressing tumor cells. This activates and redirects CTLs to PSMA-expressing tumor cells, which results in the CTL-mediated cell death of PSMA-expressing tumor cells. PSMA, a tumor associated antigen, is overexpressed on the surface of metastatic and hormone-refractory prostate cancer cells.