177 Lu-PSMA-617 radioligand therapy of metastatic castration-resistant prostate cancer: Initial 254-patient results from a prospective registry (REALITY Study)

Purpose Preliminary data from retrospective analyses and recent data from large randomized controlled trials suggest safety and efficacy of radioligand therapy (RLT) targeting prostate-specific membrane antigen (PSMA) in men with metastatic castration-resistant prostate cancer (mCRPC). Limited data on this modality have been published regarding large samples treated in everyday practice. Methods We analyzed prospectively collected registry data regarding lutetium-177 (Lu-177)-PSMA-617 RLT of 254 consecutive men with mCRPC seen in everyday academic practice. Since Lu-177-PSMA-617 was experimental salvage treatment following failure of individually appropriate conventional therapies, patients were generally elderly and heavily pretreated (median age 70 years; prior taxanes 74.0%, 188/254), with late-end-stage disease (visceral metastasis in 32.7%, 83/254). Primary endpoints were response to RLT, defined by changes from baseline serum prostate-specific antigen (PSA) concentration, PSA progression-free survival (PSA-PFS), and overall survival (OS), estimated with Kaplan-Meier statistics, and caregiver-reported and patient-reported safety. Unless noted, median (minimum-maximum) values are given. Results Patients received 3 (1-13) Lu-177-PSMA-617 activities (6.5 [2.5-11.6] GBq/cycle) every 5.7 (3.0-11.0) weeks. Best response was >= 50% PSA reduction in 52.0% of patients (132/254). PSA-PFS was 5.5 (95% confidence interval [95%CI] 4.4-6.6) months and OS, 14.5 (95%CI 11.5-17.5) months. In multivariable Cox proportional-hazards modeling, response to the initial <= 2 RLT administrations was the strongest significant prognosticator related to OS (hazard ratio 3.7 [95%CI 2.5-5.5], p < 0.001). No RLT-related deaths or treatment discontinuations occurred; the most frequent RLT-related Grade 3/4 adverse events were anemia (18/254 patients, 7.1%), thrombocytopenia (11/254, 4.3%), and lymphopenia (7/254, 2.8%). RLT-related xerostomia, all grade 1/2, was noted in 53/254 (20.9%). Conclusions In a large, prospectively observed real-world cohort with late-stage/end-stage mCRPC and conventional treatment failure, Lu-177-PSMA-617 RLT was effective, safe, and well-tolerated. Early biochemical disease control by such therapy was associated with better OS. Prospective study earlier in the disease course may be warranted.

Automated summary

Preliminary data and recent large trials suggest that Lu-177-PSMA-617 RLT targeting PSMA is safe and effective in treating mCRPC. A real-world study of 254 men with late-stage mCRPC showed the therapy was well-tolerated and associated with better overall survival when early biochemical disease control was achieved. Further prospective studies earlier in the disease course may be warranted.