Do Men Treated With Enzalutamide for Prostate Cancer PROSPER? Final Survival Results
Posted: Thursday, July 9, 2020
The final overall survival analysis of the phase III PROSPER trial supports the continued use of enzalutamide and androgen-deprivation therapy as a standard of care in men with nonmetastatic castration-resistant prostate cancer and a rapidly rising prostate specific antigen (PSA), according to results presented during the ASCO20 Virtual Scientific Program (Abstract 5515). “Enzalutamide treatment resulted in a statistically significant 27% reduced risk of death compared with placebo,” said Cora N. Sternberg, MD, of Weill Cornell Medicine, New York, and colleagues, demonstrating that initiating enzalutamide and androgen-deprivation therapy before the onset of detectable metastasis improves overall survival in such men.
Median overall survival was 67.0 months in the enzalutamide arm and 56.3 months in the placebo arm (P = .001). This overall survival benefit held despite crossover from the placebo arm to the enzalutamide arm and despite higher rates of subsequent antineoplastic therapies in men originally in the placebo arm. PROSPER originally enrolled 1,401 men with nonmetastatic castration-resistant prostate cancer whose PSA doubling time was up to 10 months and whose PSA was at least 2 ng/mL at screening. They all continued androgen-deprivation therapy but were randomly assigned 2:1 to enzalutamide at 160 mg or placebo.
With a median follow-up of about 48 months, 30.9% (n = 288) and 38.0% (n = 178) of men in the enzalutamide and placebo arms, respectively, had died (P = .0011). Safety was consistent with previous clinical trials, noted the team. Further, they reported, based on PROSPER’s previously reported metastasis-free survival results, the outcome “provides prospective validation of metastasis-free survival as a potential surrogate endpoint for overall survival in nonmetastatic castration-resistant prostate cancer.”
Disclosure: The study authors’ disclosure information can be found at coi.asco.org.
