Ian D. Davis, MBBS, PhD, spoke about updated survival results of the ENZAMET trial which analyzed enzalutamide in metastatic hormone-sensitive prostate cancer.
At the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting, Ian D. Davis, MBBS, PhD, professor of medicine and head of the Eastern Health Clinical School at Monash University and Eastern Health in Melbourne, Australia, spoke with CancerNetwork® about the phase 3 ENZAMET trial (NCT02446405), which investigated the use of enzalutamide (Xtandi) vs standard antiandrogen therapy in the first line for patients with metastatic hormone-sensitive prostate cancer.1 Davis reviewed the updated 5-year overall survival rates of 57% in the control group vs 67% in the enzalutamide group (HR, 0.70; 95% CI, 0.58-0.84).
The rationale for the ENZAMET trial was a very simple one. We conceived this idea about 10 years ago and at that time, enzalutamide was known to be effective in metastatic castration-resistant prostate cancer. We asked the question, could we improve overall survival substantially by moving it into the metastatic hormone-sensitive prostate cancer setting? The study design was a simple randomized 1:1, open-label study, and all patients received testosterone suppression. Half of patients received enzalutamide at a standard dose, and half the patients received the standard antiandrogen [therapy as the] active control. Docetaxel use was at the discretion of the investigator.
At ASCO 2019, we presented the results of the interim analysis at the plenary session, and the study made its primary end point at that point. We showed that there was a benefit for enzalutamide in the overall cohort with a hazard ratio for death of 0.67 [95% CI, 0.52-0.86; P = .002]. The 3-year landmark survival rate was 72% for the control arm and 80% for the enzalutamide arm, and the study was a positive one.2 At ASCO 2022, we presented the results of the planned 470-event analysis, with a median of 68 months of follow-up. What was shown is that the benefit of enzalutamide has been sustained, with a hazard ratio of 0.70, very similar to what it was before. The 5-year overall survival rates now are 57% for the control arm and 67% for the enzalutamide arm. The median estimated survival in the control arm was 73 months and not yet reached for enzalutamide.