On November 26, 2019 Astellas Pharma Inc. (TSE: 4503, President and CEO: Kenji Yasukawa, Ph.D., "Astellas") reported that the China National Medical Products Administration (NMPA) approved a new drug application (NDA) for XTANDI (enzalutamide) on November 18 for the treatment of adult men with metastatic castration-resistant prostate cancer (CRPC) who are asymptomatic or mildly symptomatic after failure of androgen deprivation therapy (ADT) in whom chemotherapy is not yet clinically indicated (Press release, Astellas, NOV 26, 2019, View Source [SID1234551656]).

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The approval by the NMPA was based on the results of an Asian multinational Phase 3, randomized, double-blind, placebo controlled efficacy and safety study of enzalutamide in asymptomatic or mildly symptomatic patients with progressive metastatic prostate cancer who had disease progression despite ADT and a single-dose pharmacokinetic study in healthy Chinese volunteers (Protocol 9785-CL-0013).1

The study, Asian PREVAIL (also known as 9785-CL-0232), evaluated oral enzalutamide (160 mg/day) versus placebo plus gonadotropin-releasing hormone (GnRH) therapy or after bilateral orchiectomy. The study, involving Asian patients including approximately 200 Chinese patients, showed consistent results with those in the global pivotal Phase 3 PREVAIL study in the same target population.2

"Currently the treatment options are limited in China for men with metastatic castration-resistant prostate cancer," said Andrew Krivoshik, M.D., Ph.D., Senior Vice President and Global Therapeutic Area Head, Oncology Development, Astellas. "The approval of enzalutamide in China brings us one step closer to offering physicians a meaningful treatment option in an area where there is a high medical need."

Patients treated with enzalutamide demonstrated a statistically significant reduction in the risk of Prostate Specific Antigen (PSA) progression (Hazard Ratio of 0.38 [95% confidence interval: 0.27, 0.52], P < 0.0001). The median time to PSA progression was 8.31 months in the enzalutamide group versus 2.86 months in the placebo group. Treatment with enzalutamide also resulted in a statistically significant reduction in risk of radiographic disease progression or death compared with treatment with placebo with a Hazard Ratio (HR) of 0.31 (95% confidence interval: 0.20, 0.46; P<0.0001). Additionally, treatment with enzalutamide showed a statistically significant improvement in overall survival compared to treatment with placebo, with a 67% decrease in the risk of death (HR 0.33, [95% CI: 0.16, 0.67]; P=0.0015).

The safety profile observed in the Asian PREVAIL study was generally consistent with previous clinical studies in patients with metastatic CRPC.2 The most common adverse reactions (≥10%) that occurred more frequently (≥2% over placebo) in the enzalutamide-treated patients from the randomized placebo-controlled clinical trials were asthenia/fatigue, decreased appetite, hot flush, arthralgia, dizziness/vertigo, hypertension, headache, and decreased weight.

In addition to the Asian PREVAIL data involving a Chinese sub-population, the approval was supported by results from the global Phase 3 PREVAIL trial, which were published in the New England Journal of Medicine in 2014. The Phase 3 PREVAIL trial was a randomized, double-blind, placebo-controlled, multi-national trial that enrolled more than 1,700 patients at sites in the United States, Canada, Europe, Australia, Russia, Israel and Asia including Japan.2

Enzalutamide is a standard of care for men with metastatic CRPC in countries where it is available. Since 2012, it has been prescribed to more than 420,000 patients worldwide.3 Prostate cancer is the second most common cancer in men worldwide4 and in China it has become the most common tumor in male urinary malignancies.5

"The approval of enzalutamide is an important milestone. Tens of thousands of Chinese patients with metastatic castration-resistant prostate cancer could potentially benefit from the reduced risk of disease progression and death found in the Asian PREVAIL study," said Hiroshi Hamaguchi, President, Astellas Greater China Commercial. "The approval also demonstrates a significant step forward for Astellas, with enzalutamide being the first Astellas oncology treatment approved in China."