Enzalutamide Plus Testosterone Suppression Improved OS in Metastatic Hormone-Sensitive Prostate Cancer

Enzalutamide added to testosterone suppression and compared with an active comparator of non-steroidal anti-androgen (NSAA) provided clinically meaningful improvement in overall survival for men with metastatic hormone-sensitive prostate cancer (mHSPC), according to an updated overall survival analysis of the ENZAMET trial (Abstract LBA5004).

Ian D. Davis, PhD, MBBS, of Eastern Health Clinical School, Monash University, presented the results at the 2022 ASCO Annual Meeting.

“Enzalutamide should be considered in all patients with metastatic disease and especially those in whom docetaxel may be considered unsuitable,” Dr. Davis said.

ENZAMET was an international cooperative group trial of enzalutamide in mHSPC. The trial randomly assigned 1,125 patients to testosterone suppression plus either a conventional NSAA or enzalutamide.

Dr. Davis explained that the first planned interim analysis, done with median follow-up of 34 months, showed that the addition of enzalutamide to first-line therapy improved overall survival for the overall cohort with a hazard ratio (HR) for death of 0.67. Clinical and PSA-progression free survival were improved for all subgroups, but overall survival was not improved with enzalutamide added to docetaxel.

“It was clear that longer follow-up would be required,” Dr. Davis said.

This final analysis was done after 476 deaths and with a median follow-up of 68 months.

The HR for death was 30% lower among all groups assigned to enzalutamide compared with the control group (HR=0.70; 95% CI, 0.58-0.64; P<.001). Median overall survival was 73.2 months for the control arm compared with not reached for enzalutamide. The 5-year overall survival rate was 57% for the control arm compared with 67% for enzalutamide. This showed that the initial benefit seen persisted with an additional 3 years of follow-up.

Dr. Davis said that benefits were more pronounced in patients with low volume disease, and were also seen in the subgroup with M1 high volume mHSPC despite the relatively high survival with testosterone suppression plus docetaxel plus NSAA.