177Lu-PSMA-617 Radioligand Treatment in Elderly Patients with Metastatic Castration-resistant Prostate Cancer: Therapeutic Efficacy and Safety Assessment

Objective: This study aimed to evaluate the therapeutic efficacy and safety of (177)Lutetium-Prostate Specific Membrane Antigen (Lu-177-PSMA-617) radioligand treatment (RLT) in metastatic castration-resistant prostate cancer (mCRPC) patients with aged older than 75 years. Methods: A total of 37 patients with mCRPC aged older than 75 years treated with Lu-177- PSMA-617 were included in this study. Pre-therapy and post-therapy biochemical, metabolic, and clinical response results and Hb, TLC, platelet, serum creatinine and bilirubin levels were checked to evaluate the therapeutic efficacy and toxicity profile. The Common Terminology Criteria for Adverse Events was used for grading adverse events caused by Lu-177-PSMA-617 treatment. Results: The mean age of the patients included in the study was 79.8 +/- 2.9 (76-92). The number of Lu-177-PSMA-617 treatment cycles ranged from two to four, and the mean administered radioactivity dose was 5.6 +/- 0.8 GBq per cycle. Partial biochemical response (PR) and partial metabolic response (PMR) were observed in 11 (29.7%) and 15 (40.6%) patients after treatment, respectively. Although improvement in ECOG scores was observed in 5 (13.5%) patients after treatment, it was not statistically significant. Grade 2 and 3 Hb toxicity was observed in 10 (27%) and 2 (5.4%) patients, respectively. Grade 2 leukocytopenia in six patients, Grade 1 thrombocytopenia in six patients, and Grade 2 serum creatinine toxicity in five patients were seen after the treatment. On the other hand, no patients developed liver toxicity and grade 3 or 4 leukocytopenia, thrombocytopenia or creatinine toxicity. Conclusion: Lu-177-PSMA-617 treatment was a safe and effective treatment option for properly selected elderly mCRPC patients.