Radioligand therapy of metastatic prostate cancer using (177)Lu-PSMA-617 after radiation exposure to (223)Ra-dichloride

Radioligand therapy with (177)Lu-PSMA-617 is an innovative and effective therapy for castrate-resistant metastatic prostate cancer patients. For patients with symptomatic bone metastases without visceral metastases, the guidelines recommend radionuclide therapy with (223)Ra-dichloride as a single therapeutic agent or in combination with hormone therapy. The aim of this study was to evaluate the safety of repeated cycles of (177)Lu-PSMA-617 after exposure to more cycles of (223)Ra. Forty-nine patients were treated with three cycles of Lu-PSMA-617 divided into two groups subjected to a history of therapy with (223)Ra. Group 1 included 20 patients, who had received therapy with (223)Ra prior to Lu-PSMA-617 therapy. Group 2, which was the control group regarding hematotoxicity, comprised 29 patients without any history of a bone-targeted radionuclide therapy. No CTC 4° hematotoxicity was observed in the entire study population. There was no CTC 3° or CTC 4° leucopenia in either group. One and three patients from group 1 and 2, respectively, showed CTC 3° anemia. In group 1 there was significantly more CTC 2° anemia (50% vs. 6.9%) (p=0.008). One patient from group 1 (5%) showed a CTC 3° thrombocytopenia without any concurrent anemia, and two patients from group 2 (7%) showed a CTC 3° thrombocytopenia, one with CTC 3° anemia and one without any anemia. There were no significant differences between the two groups regarding leucopenia and thrombocytopenia. These results confirmed that performing repeated cycles of Lu-PSMA-617 after (223)Ra seems to be safe with a very small probability of hematotoxicity.

Oncotarget. 2017 Feb 25*** epublish ***

Hojjat Ahmadzadehfar, Stefanie Zimbelmann, Anna Yordanova, Rolf Fimmers, Stefan Kürpig, Elisabeth Eppard, Florian C Gaertner, Xiao Wei, Stefan Hauser, Markus Essler

Department of Nuclear Medicine, University Hospital Bonn, Bonn, Germany., Institute for Medical Biometry, Informatics and Epidemiology, University of Bonn, Bonn, Germany., Department of Urology, University Hospital Bonn, Bonn, Germany.