Efficacy, safety and prognostic factors affecting overall survival among metastatic prostate cancer patients undergoing treatment with 177Lu-PSMA-617: A single center study

Abstract Background Determining the efficacy, safety, and prognostic factors affecting overall survival (OS) among metastatic prostate cancer patients undergoing PSMA-targeted radioligand therapy (PRLT). Method In this retrospective study, from November 2016 and December 2019, 43 heavily pretreated (90.7% on 1st line androgen deprivation therapy (ADT), 53.5% on 2nd line ADT, 58.1% on docetaxel) metastatic prostate cancer patients with median age of 71 years (range: 51−88 years) were enrolled. Treatment cycles were repeated every 8 weeks (range: 6–12 weeks). To evaluate the biochemical response after each cycle, prostate specific antigen (PSA) levels were measured and analyzed according to the Prostate Cancer Working Group 3 (PCWG3) criteria cutoffs. Possible adverse events after therapy were retrospectively classified according to the Common Toxicity Criteria for Adverse Events (CTCAE) v.5.0. Kaplan-Meier and multivariable Cox proportional hazard regression analyses were used to identify factors associated with OS. Results A total of 112 cycles of PRLT with a median of 3 cycles (range: 1–6) and median administered activity per cycle of 6.29 GBq (range: 4.45–7.7 GBq) were used. PSA decline was observed in 65.1% of patients, and best PSA decline of ≥50% and ≥90% were achieved in 39.5% and 23.3% of patients, respectively. Major (grade III) anemia and thrombocytopenia occurred in 11.6% and 7% of patients, respectively. Median OS and median PSA progression-free survival were 52 and 20 weeks, respectively. In univariate analysis, baseline hemoglobin 2, baseline PSA ≥ 115 ng/mL, cumulative dose of 177Lu-PSMA Conclusion PRLT with 177Lu-PSMA is well-tolerated and effective in metastatic prostate cancer patients who have no other treatment options available. The novel prognostic markers found in this study (high platelet count, superscan pattern) were associated with poor overall survival.