Enzalutamide and Survival in Nonmetastatic, Castration-Resistant Prostate Cancer.

Preliminary trial results showed that enzalutamide significantly improved metastasis-free survival among men who had nonmetastatic, castration-resistant prostate cancer and rapidly increasing prostate-specific antigen (PSA) levels while taking androgen-deprivation therapy. Results from the final analysis of overall survival have not yet been reported.

In this double-blind, phase 3 trial, men with nonmetastatic, castration-resistant prostate cancer (defined on the basis of conventional imaging and a PSA doubling time of ≤10 months) who were continuing to receive androgen-deprivation therapy were randomly assigned (in a 2:1 ratio) to receive enzalutamide at a dose of 160 mg or placebo once daily. Overall survival was assessed with a group sequential testing procedure and an O'Brien-Fleming-type alpha-spending function.

As of October 15, 2019, a total of 288 of 933 patients (31%) in the enzalutamide group and 178 of 468 (38%) in the placebo group had died. Median overall survival was 67.0 months (95% confidence interval [CI], 64.0 to not reached) in the enzalutamide group and 56.3 months (95% CI, 54.4 to 63.0) in the placebo group (hazard ratio for death, 0.73; 95% CI, 0.61 to 0.89; P = 0.001). The exposure-adjusted rate of adverse events of grade 3 or higher was 17 per 100 patient-years in the enzalutamide group and 20 per 100 patient-years in the placebo group. Adverse events in the enzalutamide group were consistent with those previously reported for enzalutamide; the most frequently reported events were fatigue and musculoskeletal events.

Enzalutamide plus androgen-deprivation therapy resulted in longer median overall survival than placebo plus androgen-deprivation therapy among men with nonmetastatic, castration-resistant prostate cancer and a rapidly rising PSA level. The risk of death associated with enzalutamide was 27% lower than with placebo. Adverse events were consistent with the established safety profile of enzalutamide. (Funded by Pfizer and Astellas Pharma; PROSPER ClinicalTrials.gov number, NCT02003924.).

The New England journal of medicine. 2020 May 29 [Epub ahead of print]

Cora N Sternberg, Karim Fizazi, Fred Saad, Neal D Shore, Ugo De Giorgi, David F Penson, Ubirajara Ferreira, Eleni Efstathiou, Katarzyna Madziarska, Michael P Kolinsky, Daniel I G Cubero, Bettina Noerby, Fabian Zohren, Xun Lin, Katharina Modelska, Jennifer Sugg, Joyce Steinberg, Maha Hussain, PROSPER Investigators

From the Englander Institute for Precision Medicine, Weill Cornell Medicine, New York (C.N.S.); the University of Paris Saclay, Villejuif, France (K.F.); the University of Montreal Hospital Center, Montreal (F.S.), and Cross Cancer Institute, University of Alberta, Edmonton (M.P.K.) - both in Canada; the Carolina Urologic Research Center, Myrtle Beach, SC (N.D.S.); Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola, Italy (U.D.); Vanderbilt University, Nashville (D.F.P.); the State University of Campinas (Unicamp), Campinas (U.F.), and the ABC Foundation School of Medicine, Santo André (D.I.G.C.) - both in Brazil; M.D. Anderson Cancer Center, Houston (E.E.); Wroclaw Medical University, Wroclaw, Poland (K. Madziarska); Sygehus Lillebælt, Vejle, Denmark (B.N.); Pfizer, La Jolla (F.Z., X.L.), and Pfizer, San Francisco (K. Modelska) - both in California; and Astellas Pharma, Northbrook (J. Sugg, J. Steinberg), and the Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago (M.H.) - both in Illinois.