Definition

A radioconjugate composed of PSMA-trillium, a human prostate-specific membrane antigen (PSMA)-targeting small molecule that is linked to an albumin-binding moiety, and conjugated to the alpha-emitting radioisotope actinium Ac 225, with potential antineoplastic activity. Upon administration, actinium Ac 225-PSMA-trillium targets and binds to PSMA-expressing tumor cells. Upon binding, the radioisotope moiety delivers a cytotoxic dose of alpha radiation to PSMA-expressing tumor cells. PSMA, a tumor-associated antigen (TAA) and type II transmembrane protein, is expressed on the membrane of prostatic epithelial cells and overexpressed on prostate tumor cells as well as a variety of other solid tumors. The albumin-binding moiety targets and binds to albumin, which may improve therapeutic efficacy and reduce side effects in normal organs.