XTANDI™ (enzalutamide) Shows Long-Term Survival in Metastatic Hormone-Sensitive Prostate Cancer

Astellas Pharma Inc. and Pfizer Inc. have announced promising results from an extended analysis of the Phase 3 ARCHES trial. The study highlights the survival benefits of XTANDI (enzalutamide) combined with androgen deprivation therapy (ADT) in treating men with metastatic hormone-sensitive prostate cancer (mHSPC). Over a five-year period, the treatment demonstrated a significant reduction in the risk of death compared to a placebo plus ADT, marking a 30% decrease in mortality risk.

The data, presented at the American Society of Clinical Oncology (ASCO) Annual Meeting, underlines XTANDI's effectiveness in enhancing long-term survival rates. The trial involved 1,150 mHSPC patients globally, who received XTANDI alongside ADT. After a median follow-up period of 61.4 months, the probability of survival with XTANDI plus ADT reached 66% at the five-year mark, substantially higher compared to 53% for those on placebo plus ADT.

Dr. Andrew J. Armstrong, primary investigator of the ARCHES trial, expressed optimism about the improved survival rates for patients with this type of prostate cancer, traditionally associated with low survival prospects. The data signifies a 13% absolute increase in survival, with notable benefits across various patient subgroups, including those with high-volume disease and no prior use of docetaxel. This suggests XTANDI as a potential standard care option for mHSPC treatment, offering meaningful improvements in patient outcomes.

Detailed analysis of specific patient groups revealed a sustained survival benefit across different categories. For patients with high-volume disease, there was a 36-month improvement in median overall survival, and similar trends were observed in those who had previously received docetaxel therapy. The incidence of adverse effects aligned with previous analyses, with no new safety concerns emerging over the follow-up period.

Shontelle Dodson, Executive Vice President at Astellas, highlighted the consistent efficacy and transformative impact of XTANDI in managing advanced prostate cancer. The expanding body of evidence supports its role in altering the prognosis for patients with mHSPC, establishing XTANDI plus ADT as the recommended treatment regimen.

Further reinforcing XTANDI's efficacy, an independent trial conducted over eight years, known as ENZAMET, also demonstrated favorable outcomes for patients with mHSPC. This study compared the effects of enzalutamide against non-steroidal anti-androgen (NSAA), both with testosterone suppression therapy, showing reduced mortality risk and enhanced progression-free survival rates.

Christopher Sweeney, the primary investigator for the ENZAMET study, emphasized the long-term benefits of XTANDI, which remained evident up to eight years post-treatment. The sustained progression-free and overall survival benefits underscore XTANDI’s value as a treatment option for metastatic hormone-sensitive prostate cancer.

Overall, XTANDI has been approved in over 90 countries and has been administered to more than a million patients globally since its initial launch in 2012. The collective findings from the ARCHES and ENZAMET trials highlight XTANDI’s pivotal role in advancing prostate cancer treatment, offering hope for better management and outcomes for patients with this challenging condition.