Apalutamide and Overall Survival in Prostate Cancer

The phase 3 SPARTAN study evaluated apalutamide versus placebo in patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) and prostate-specific antigen doubling time of ≤10 mo. At primary analysis, apalutamide improved median metastasis-free survival (MFS) by 2 yr and overall survival (OS) data were immature.

We report the prespecified event-driven final analysis for OS.

A total of 1207 patients with nmCRPC (diagnosed by conventional imaging) were randomised 2:1 to apalutamide (240mg/d) or placebo, plus on-going androgen deprivation therapy. After MFS was met and the study was unblinded, 76 (19%) patients still receiving placebo crossed over to apalutamide.

OS and time to cytotoxic chemotherapy (TTChemo) were analysed by group-sequential testing with O'Brien-Fleming-type alpha spending function.

At median 52-mo follow-up, 428 deaths had occurred. The median treatment duration was 32.9 mo for apalutamide group and 11.5 mo for placebo group. Median OS was markedly longer with apalutamide versus placebo, reaching prespecified statistical significance (73.9 vs 59.9 mo, hazard ratio [HR]: 0.78 [95% confidence interval {CI}, 0.64-0.96]; p=0.016). Apalutamide also lengthened TTChemo versus placebo (HR: 0.63 [95% CI, 0.49-0.81]; p=0.0002). Discontinuation rates in apalutamide and placebo groups due to progressive disease were 43% and 74%, and due to adverse events 15% and 8.4%, respectively. Subsequent life-prolonging therapy was received by 371 (46%) patients in the apalutamide arm and by 338 (84%) patients in the placebo arm including 59 patients who received apalutamide after crossover. Safety was consistent with previous reports; when adverse events were adjusted for treatment exposure, rash had the greatest difference of incidence between the apalutamide and placebo groups.

Extension of OS with apalutamide compared with placebo conferred impactful benefit in patients with nmCRPC. There was a 22% reduction in the hazard of death in the apalutamide group despite 19% crossover (placebo to apalutamide) and higher rates of subsequent therapy in the placebo group.

With data presented herein, all primary and secondary study end points of SPARTAN were met; findings demonstrate the value of apalutamide as a treatment option for nonmetastatic castration-resistant prostate cancer.

European urology. 2020 Sep 06 [Epub ahead of print]

Matthew R Smith, Fred Saad, Simon Chowdhury, Stéphane Oudard, Boris A Hadaschik, Julie N Graff, David Olmos, Paul N Mainwaring, Ji Youl Lee, Hiroji Uemura, Peter De Porre, Andressa A Smith, Sabine D Brookman-May, Susan Li, Ke Zhang, Brendan Rooney, Angela Lopez-Gitlitz, Eric J Small

Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, MA, USA. Electronic address: ., Centre Hospitalier de l'Université de Montréal, Université de Montréal, Montréal, Québec, Canada., Guy's, King's, and St. Thomas' Hospitals, and Sarah Cannon Research Institute, London, UK., Georges Pompidou Hospital, University de Paris, Paris, France., University of Duisburg-Essen, Essen, and Ruprecht-Karls University Heidelberg, Heidelberg, Germany., VA Portland Health Care System, Portland and Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA., Spanish National Cancer Research Centre (CNIO), Madrid and Biomedical Research Institute of Málaga (IBIMA), Spain., Canossa Hospital, Oxley, Queensland, Australia., St. Mary's Hospital of Catholic University, Seoul, South Korea., Yokohama City University Medical Center, Yokohama, Japan., Janssen Research & Development, Beerse, Belgium., Janssen Research & Development, Spring House, PA, USA., Janssen Research & Development, Los Angeles, CA, USA; Ludwig Maximilians University, Munich, Germany., Janssen Research & Development, San Diego, CA, USA., Janssen Research & Development, High Wycombe, UK., Janssen Research & Development, Los Angeles, CA, USA., Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, USA.

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