(UroToday.com) At the 2022 American Society of Clinical Oncology Annual Meeting held in Chicago and virtually, the poster session focused on Prostate, Testicular, and Penile cancers on Monday afternoon included a presentation from Dr. Scott T. Tagawa discussing the tolerability of theranostic treatment with 177Lu-PSMA among men with metastatic castration-resistant prostate cancer (mCRPC), stratified by their treatment exposure, in men treated within the VISION trial.
There has been significant interest recently in the field of theranostics for prostate cancer. The phase II TheraP and phase III VISION trials demonstrated the benefit of 177Lu-PSMA-617 in patients with heavily pre-treated mCRPC with evidence that it PSMA prolongs survival and improves the quality of life. Interestingly, this occurred in spite of a higher rate of adverse events (AEs) than standard of care (SoC) alone. The authors sought to assess to what degree AE incidence was affected by the exposure to 177Lu-PSMA-617.
While previously presented and published, in brief, VISION was an international, open-label study that enrolled adults with PSMA-positive mCRPC previously treated with ≥ 1 androgen receptor pathway inhibitor and 1–2 taxane regimens (NCT03511664). Eligible patients were randomized to 177Lu-PSMA-617 (7.4 GBq every 6 weeks, ≤ 6 cycles) with standard of care or SoC alone. 177Lu-PSMA-617 cycle duration was generally ̃6 weeks. The primary endpoints were rPFS and OS with safety as a secondary endpoint. AE analysis was performed by exposure to 177Lu-PSMA-617 in pre-specified subgroups. The cycle of onset in which an AE first occurred in a patient at maximum grade was assessed.
The median duration of treatment cycles was 6 weeks for cycles 1 to 5 was 6 weeks; for cycle 6, it was 26.6 weeks given that this observation period continued following the last cycle. Of the 529 patients in the 177Lu-PSMA-617 group, 240 (45.4%) received 4 or more cycles and 289 (54.6%) received 5 or 6 cycles of treatment.
In patients who received 4 or more cycles of therapy, 234 (97.5%) of treatment-emergent AEs (TEAEs) were seen during these treatment cycles. Further, in this group, 100 (41.7%) serious AEs, 205 (85.4%) treatment-related AEs, and 13 (5.4%) fatal treatment-related AEs were noted. Among those who completed 5 or 6 cycles of therapy, 285 (98.6%) treatment-emergent AEs (TEAEs), 92 (31.8%) serious TEAEs, 246 (85.1%) treatment-related AEs, and 6 (2.1%) fatal TEAEs were found.
The authors noted that more than 50% of patients with mCRPC were able to receive 5 or 6 cycles (of a planned 6 cycle) of 177Lu-PSMA-617. For cycles 1–5, TEAEs occurred at every cycle, with similar frequency. More TEAEs were observed in cycle 6, reflecting its longer median duration than other cycles.
Presented by: Scott T. Tagawa, MD, Associate Professor of Clinical Medicine, Clinical Urology, Medical Director, Genitourinary Oncology Research Program, Weill Cornell Medicine, New York, NY