FOLH1 and prostate cancer: The most advanced clinical PSMA RLT study of alpha-ray-emitting radioisotopes involves Actinium-225 (225Ac)-PSMA-617, although in a report of 17 patients with advanced prostate cancer treated with chemotherapy, more than 91% showed a decrease in PSA levels of more than 50%, with 41% saying that it had dropped below the measurement limit.