Definition

A radioconjugate consisting of a neurotensin receptor type 1 (NTSR1)-targeting small molecule antagonist labeled with the alpha-emitting radioisotope actinium Ac 225, with potential antineoplastic activity. Upon administration of actinium Ac 225 FPI-2059, the NTSR1-targeting moiety targets and binds to NTSR1 expressed on tumor cells. Upon binding, the radioisotope moiety delivers a cytotoxic dose of alpha radiation to NTSR1-expressing tumor cells. NTSR1, a G protein-coupled receptor for the tridecapeptide neurotensin (NTS), is overexpressed in certain types of cancers and plays a key role in tumor cell proliferation.