Enzalutamide extends PFS in castration-resistant prostate cancer
Patients with castration-resistant prostate cancer treated with enzalutamide demonstrated significantly longer PFS than those treated with bicalutamide, according to topline results of the phase 2 STRIVE trial released by Astellas.
The trial included 396 patients with castration-resistant prostate cancer. About two-thirds of the patients (n = 257; 64.8%) had metastatic disease. The other 139 patients had nonmetastatic disease that progressed after surgical castration or treatment with a luteinizing hormone-releasing hormone analogue therapy.
Researchers randomly assigned patients to 160 mg once-daily enzalutamide (Xtandi; Astellas, Medivation) — an androgen receptor antagonist — or 50 mg once-daily bicalutamide, an oral non-steroidal antiandrogen. PFS served as the primary endpoint.
Patients assigned enzalutamide demonstrated a significant improvement in median PFS (19.4 months vs. 5.7 months; HR = 0.24; 95% CI, 0.18-0.32), according to a press release issued by Astellas. Median time on treatment also was longer in the enzalutamide group (14.7 months vs. 8.4 months).
Common side effects reported more frequently in the enzalutamide group included back pain, fatigue, hot flush, hypertension, falls, dizziness and decreased appetite.
Researchers observed similar rates of serious adverse events in both groups (enzalutamide, 29.4%; bicalutamide, 28.3%). Incidence of grade 3 or higher cardiac adverse events was 5.1% in the enzalutamide group and 4% in the bicalutamide group. Researchers reported one seizure in the enzalutamide group and none in the bicalutamide group.
Additional safety data and results related to secondary endpoints will be submitted for presentation at upcoming medical conferences, according to the press release.