Astellas Pharma and Pfizer have announced promising five-year follow-up data from the Phase 3 ARCHES trial, highlighting the overall survival benefits of Xtandi (enzalutamide) in men with metastatic hormone-sensitive prostate cancer (mHSPC).
The androgen receptor inhibitor, when combined with androgen deprivation therapy (ADT), showed a 30% reduction in the risk of death compared to placebo plus ADT.
The study, which followed patients for a median of 61.4 months, revealed a potential 66% survival at five years for those treated with Xtandi plus ADT, compared to a 53% survival with placebo plus ADT.
The study findings strengthen Xtandi’s role as a standard of care in treating mHSPC.
Xtandi is the first androgen receptor inhibitor to show an overall survival benefit at five years in mHSPC patients.
Its effectiveness was noted across various patient subgroups, including those with high-volume disease, no prior docetaxel use, and synchronous disease.
The incidence of treatment-emergent adverse events remained consistent with previous analyses, with no new safety signals identified.
Astellas executive vice president and medical affairs head Shontelle Dodson said: “The survival benefits of intervention with XTANDI in advanced prostate cancer are well-recognised.
“The collective – and growing – body of data for XTANDI continues to reinforce its long-term efficacy and patient impact in prostate cancer, including in the metastatic setting, and shows that XTANDI is changing the trajectory of those living with the disease.”
Pfizer oncology chief development officer Johanna Bendell said: “Until recently, patients with metastatic hormone-sensitive prostate cancer faced a poor prognosis, particularly in advanced stages, often due to treatment resistance.
“As the only androgen receptor inhibitor demonstrating sustained five-year survival in this patient population, these data further reinforce XTANDI combined with androgen deprivation therapy as the standard-of-care for treating this advanced disease.”
The results from the ARCHES trial will be submitted for publication in a peer-reviewed scholarly journal soon.
In addition to the ARCHES data, eight-year results from the ENZAMET study will be presented at the American Society of Clinical Oncology (ASCO).
The ENZAMET study is sponsored by the University of Sydney and led by the Australian and New Zealand Urogenital and Prostate Cancer Trials Group.
In the study, Xtandi was compared with non-steroidal anti-androgens (NSAA), alongside testosterone suppression.
With a median follow-up of 98 months, the ENZAMET study showed a median overall survival of eight years for the Xtandi group, compared to 5.8 years for the NSAA group.
The study also reported better progression-free survival for Xtandi over NSAA.
Since its initial approval in 2012, Xtandi has been approved in over 90 countries, including the US, the European Union (EU), and Japan.
ARCHES study primary investigator Andrew Armstrong said: “Historically, the likelihood of survival at five years for men with metastatic hormone-sensitive prostate cancer was low, but with advancements in initial treatment intensification like what we’ve seen with XTANDI, this is now becoming the standard.
“In our five-year follow-up of the global ARCHES trial, two-thirds of men are now surviving five years, representing a 13% absolute and 30% relative improvement over standard hormonal therapy alone, with benefits in patients with high and low disease burden that are meaningful to our patients.”
ENZAMET follow-up primary investigator Christopher Sweeney said: “Data from the eight-year follow-up of XTANDI are highly encouraging, as they show the progression-free survival and overall survival benefits are sustained out to at least eight years.
“These results further support the value of XTANDI as a treatment regimen for metastatic hormone-sensitive prostate cancer.”
