225Ac-Prostate-Specific Membrane Antigen Therapy for Castration-Resistant Prostate Cancer

Purpose Prostate-specific membrane antigen (PSMA)–targeted therapies are among the current promising treatments. We present our preliminary results on the use of 225 Ac-PSMA therapy in patients with metastatic castration-resistant prostate cancer as a single center. Methods Twelve advanced stage metastatic castration-resistant prostate cancer patients who received 225 Ac-PSMA therapy were recruited in this retrospective study. Patients were treated with 225 Ac-PSMA therapy every 8 weeks, and prostate-specific antigen (PSA) response was analyzed. Meanwhile, overall survival (OS) and progression-free survival (PFS) were estimated. Hematological and nonhematological adverse effects were recorded before and at 8 weeks after the last treatment cycle. Results In total, 25 cycles of 225 Ac-PSMA were administered to 12 patients. The pretreatment median PSA level was 129 ng/mL. After the first cycle of therapy, any PSA response was observed in 9 of 12 patients, whereas 6 of them had biochemical response of >50%. Four of 12 patients reached the best PSA response after the first treatment cycle, whereas 3 patients after the second and 2 patients after the third cycle. The median PFS and OS were 4 and 10 months, respectively. For patients with any PSA response after the first cycle, OS was found to be higher despite without any statistical significance (10 vs 4 months; P = 0.301) when compared with the nonresponsive group. No significant difference was encountered in terms of adverse effect in the pretreatment and posttreatment era. Conclusions Our preliminary results are encouraging, especially patients who had PSA response after the first cycle of 225 Ac-PSMA therapy.