RT Journal Article SR Electronic T1 225Ac-PSMA-617 for PSMA-Targeted α-Radiation Therapy of Metastatic Castration-Resistant Prostate Cancer JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1941 OP 1944 DO 10.2967/jnumed.116.178673 VO 57 IS 12 A1 Clemens Kratochwil A1 Frank Bruchertseifer A1 Frederik L. Giesel A1 Mirjam Weis A1 Frederik A. Verburg A1 Felix Mottaghy A1 Klaus Kopka A1 Christos Apostolidis A1 Uwe Haberkorn A1 Alfred Morgenstern YR 2016 UL http://jnm.snmjournals.org/content/57/12/1941.abstract AB Prostate-specific membrane antigen (PSMA) is a promising target in prostate cancer. Recently, we started the first-in-human treatment with an α-radionuclide–labeled PSMA ligand. Although the case series is still ongoing, we here report in advance about two patients in highly challenging clinical situations who showed a complete response to 225Ac-PSMA-617 therapy. Methods: 68Ga-PSMA-11 PET/CT validated the presence of the PSMA-positive tumor phenotype. A 100-kBq activity of 225Ac-PSMA-617 per kilogram of body weight was administered bimonthly. Prostate-specific antigen response and hematologic toxicity were measured at least every 4 wk. Restaging was performed with 68Ga-PSMA-11 PET/CT. Results: Both patients experienced a prostate-specific antigen decline to below the measurable level and showed a complete response on imaging. No relevant hematologic toxicity was observed. Xerostomia was the only mentionable clinical side effect. Conclusion: Targeted α-therapy with 225Ac-PSMA-617, although still experimental, obviously has strong potential to significantly benefit advanced-stage prostate cancer patients.