Astellas Pharma Inc. (TSE: 4503) and Pfizer Inc. (NYSE: PFE)  announced compelling five-year overall survival (OS) results from the open-label extension of the Phase 3 ARCHES trial (NCT02677896), further solidifying XTANDI® (enzalutamide) in combination with androgen deprivation therapy (ADT) as a standard of care for metastatic hormone-sensitive prostate cancer (mHSPC).

After a median follow-up of 61.4 months, the combination of XTANDI + ADT showed a 30% reduction in the risk of death compared to placebo + ADT, with a five-year survival probability of 66% versus 53%, respectively. These data will be presented during an oral session (Abstract #5005) at the American Society of Clinical Oncology (ASCO) Annual Meeting on June 3 in Chicago.

“In our five-year follow-up, two-thirds of men with mHSPC are now surviving beyond five years—representing a 13% absolute and 30% relative improvement over hormonal therapy alone,” said Dr. Andrew J. Armstrong, primary investigator of ARCHES and Director of Research at the Duke Cancer Institute. “These survival benefits are meaningful, particularly for patients with both high- and low-volume disease.”

Subgroup Benefits Confirm Long-Term Efficacy

Patients with high-volume disease experienced a 36-month improvement in median OS (HR: 0.70), while those with low-volume disease (HR: 0.71), with or without prior docetaxel therapy, also showed clinically meaningful survival gains. Importantly, no new safety concerns emerged during the extended follow-up period.

“The growing body of evidence surrounding XTANDI reinforces its long-term efficacy and safety in prostate cancer, even in metastatic settings,” noted Shontelle Dodson, EVP, Head of Medical Affairs, Astellas. “XTANDI continues to change the trajectory of this disease.”

Additional Long-Term Data from ENZAMET Trial

Also at ASCO, eight-year data from the independent ENZAMET trial (NCT02446405), sponsored by the University of Sydney and ANZUP, demonstrated that XTANDI + testosterone suppression (with or without docetaxel) extended median OS to 8.0 years, compared to 5.8 years for patients on NSAA (non-steroidal anti-androgens) + testosterone suppression (HR: 0.73).
Progression-free survival (HR: 0.49) and prostate cancer-specific mortality also favored XTANDI, which remained tolerable with 33% of patients continuing on treatment after eight years.

“These data confirm the durability of XTANDI’s benefit—across both five and eight years—and validate its role in extending both progression-free and overall survival,” said Dr. Christopher Sweeney, primary investigator for ENZAMET follow-up and ANZUP Cancer Trials Group.

Global Impact

XTANDI is approved in more than 90 countries, including the U.S., EU, and Japan. Since 2012, over one million patients worldwide have been treated with XTANDI.

“XTANDI is the only androgen receptor inhibitor showing sustained survival at five years,” said Dr. Johanna Bendell, Oncology Chief Development Officer, Pfizer. “These findings underscore its critical role in improving long-term outcomes in advanced prostate cancer.”