Enzalutamide Tied to Longer OS, PFS Than Standard Care in Hormone-Sensitive Prostate Cancer

Among patients with metastatic, hormone-sensitive prostate cancer undergoing testosterone suppression, use of enzalutamide was tied to significantly longer rates of progression-free survival (PFS) and overall survival (OS) than standard care (N Engl J Med. 2019;381[2]:121-131).

Citing a lack of existing data about whether adding enzalutamide to testosterone suppression with or without early docetaxel can improve survival in this patient population, Ian D. Davis, MB, BS, PhD, and colleagues conducted a phase 3, open-label clinical trial.

A total of 1125 patients were enrolled and randomized to receive testosterone suppression plus enzalutamide or standard care with nonsteroidal antiandrogen therapy. The primary end point was OS, and secondary end points included PFS (determined by the prostate-specific antigen [PSA] level), clinical PFS, and adverse events.

The median follow-up time frame was 34 months, during which time 102 and 143 deaths occurred in the enzalutamide and standard-care arms, respectively (hazard ratio [HR], 0.67; 95% CI, 0.52-0.86; P = .002). Kaplan-Meier estimates of 3-year OS were 80% in the enzalutamide arm and 72% in the standard-care arm, based on 94 and 130 events, respectively.

According to Dr Davis et al, better PSA PFS rates were seen with enzalutamide versus standard care (174 and 333 events, respectively; HR, 0.39; P <.001), as were clinical PFS rates (167 and 320 events, respectively; HR, 0.40; P <.001).

Patients were more likely to discontinue therapy due to adverse events in the enzalutamide arm than in the standard-care arm (33 and 14 events, respectively). Of note, fatigue was more common with enzalutamide than with standard care, and seizures occurred in 7 patients in the enzalutamide arm versus 0 patients in the standard-care arm.

In conclusion, enzalutamide was found to be associated with significantly longer rates of PFS and OS compared with standard care in patients with metastatic, hormone-sensitive prostate cancer receiving testosterone suppression.

“The enzalutamide group had a higher incidence of seizures and other toxic effects, especially among those treated with early docetaxel,” Dr Davis and colleagues added.—Hina Porcelli