PSMA targeted radioligandtherapy in metastatic castration resistant prostate cancer after chemotherapy, abiraterone and/or enzalutamide. A retrospective analysis of overall survival

Aim: Our aim was to evaluate overall survival and parameters prognosticating longer survival in a large and homogeneous group of patients treated with ¹⁷⁷Lu-PSMA-617 radioligand therapy with heavily pretreated advanced metastatic castration resistant prostate cancer.

Methods: A total of 104 patients were treated with 351 cycles of ¹⁷⁷Lu-PSMA-617. Prostate specific antigen (PSA) changes after the first cycle of therapy were documented prior to a second cycle. Patients were followed-up for overall survival (OS). Any PSA decline, PSA decline ≥50%, initial PSA, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), visceral metastases and cumulative injected activity were analyzed and evaluated according to OS. Multivariable analysis with parameters with a p-value ≤0.05 in univariate analysis was performed, additionally adjusting for age and presence of visceral metastases.

Results: A total of 51 patients (49%) died during the observation period. The majority of patients (97%) presented with bone metastases, 77% with lymph node metastases and 32% with visceral metastases. All patients were treated with at least one line of chemotherapy. Either abiraterone or enzalutamide had been given in 100% of the patients. Any PSA decline occurred in 70 (67%) and a PSA decline ≥50% in 34 (33%) of patients after the first cycle. The median OS was 56.0 weeks (95%CI: 50.5-61.5). Initial PSA decline ≥50%, initial LDH, visceral metastases, second line chemotherapy or prior radium-223 did not have an effect on survival, whereas any initial PSA decline, initial ALP <220 U/L and cumulative injected activity ≥18.8 GBq were associated with a longer survival. A step-by-step analysis revealed a PSA decline ≥20.87% as the most noticeable cut-off prognosticating longer survival, which remained an independent prognosticator of improved OS in the multivariate analysis.

Conclusion: ¹⁷⁷Lu-PSMA-617 RLT is a new effective therapeutic and seems to prolong survival in patients with advanced mCRPC pretreated with chemotherapy, abiraterone and/or enzalutamide.