Data simultaneously published in the New England Journal of Medicine and presented during the virtual scientific program of the 2020 ASCO Annual Meeting

NEW YORK and TOKYO, May 29, 2020 – Pfizer Inc. (NYSE: PFE) and Astellas Pharma Inc. (TSE: 4503, President and CEO: Kenji Yasukawa, Ph.D., “Astellas”) have announced final results from the overall survival (OS) analysis of the Phase 3 PROSPER trial, which evaluated XTANDI® (enzalutamide) plus androgen deprivation therapy (ADT) versus placebo plus ADT in men with non-metastatic castration-resistant prostate cancer (nmCRPC). In the trial, XTANDI plus ADT reduced the risk of death by 27% (n=1,401; hazard ratio [HR]=0.73; [95% confidence interval [CI]: 0.61-0.89]; p=0.001) compared to placebo plus ADT. The median OS was 67.0 months (95% CI: 64.0 to not reached) for men who received XTANDI plus ADT compared to 56.3 months (95% CI: 54.4 to 63.0) with placebo plus ADT. OS was a key secondary endpoint of the trial.

These data were simultaneously published online in the New England Journal of Medicine and presented during the virtual scientific program of the 2020 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract #5515).

“Overall survival is a critical endpoint in evaluating a prostate cancer medicine,” said Cora N. Sternberg, M.D., F.A.C.P., Clinical Director, Englander Institute for Precision Medicine and Professor of Medicine in Hematology & Oncology, Weill Cornell Medicine and NewYork-Presbyterian. “These results add to the body of evidence supporting XTANDI’s potential to reduce the risk of death in men with castration-resistant prostate cancer.”

In findings published in the New England Journal of Medicine in 2018, the PROSPER trial met its primary endpoint of metastasis-free survival (MFS), demonstrating a significant reduction in the risk of developing metastasis or death with XTANDI plus ADT compared to ADT alone in men with nmCRPC (HR=0.29 [95% CI: 0.24-0.35]; p<0.001). MFS was measured as the time from patients entering the trial until their cancer was radiographically detected as having metastasized, or until death, within 112 days of treatment discontinuation.

The safety profile observed in the final OS analysis was consistent with the 2018 primary analysis and the established safety profile of enzalutamide. The most common adverse reactions irrespective of relationship to study drug that occurred more frequently (≥10%) in XTANDI plus ADT-treated patients in the PROSPER OS analysis were fatigue (37% vs 16%), hypertension (17% vs 6%), asthenia (10% vs 7%), back pain (13% vs 8%), dizziness (12% vs 6%), diarrhea (12% vs 10%), nausea (13% vs 9%), hot flush (14% vs 8%), fall (18% vs 5%), arthralgia (13% vs 8%), constipation (13% vs 8%), hematuria (10% vs 9%), headache (11% vs 5%) and decreased appetite (12% vs 5%). In this analysis of the PROSPER trial, Grade 3 or higher adverse reactions were reported in 48% of men treated with XTANDI plus ADT and in 27% of men treated with placebo plus ADT.

 

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