Key clinical point: Low-dose enzalutamide demonstrates a response rate and progression-free survival (PFS) comparable with that of the standard dose in elderly chemotherapy-naive patients with metastatic castration-resistant prostate cancer (CRPC).

Major finding: At 12 weeks, a higher proportion of patients in the low-dose group reported a prostate-specific antigen decrease of ≥50% than in the standard-dose group; however, the difference was not significant (66.7% vs. 45.0%; P = .152). Median PFS was similar between the low- and standard-dose groups (11.2 vs. 11.9 months; P = .612).

Study details: The study evaluated 59 patients aged ≥75 years with metastatic CRPC. Sixteen patients received low-dose enzalutamide (≤80 mg/day) and 43 received the standard dose.

Disclosures: No information available on funding and authors' disclosures.

Commentary

“Enzalutamide is widely used for the treatment of metastatic castrate-resistant prostate cancer. However, it does have potentially bothersome side effects, such as fatigue, hypertension, and rarely, seizures. Doses are often reduced for patients with side effects, but the efficacy of this approach is not known. Vinh-Hung et al conducted a retrospective cohort study to determine whether lower dose enzalutamide (at < 80 mg daily) resulted in lower efficacy than standard dose enzalutamide (160 mg daily). Sixteen of 59 patients evaluated received the lower dosage. There was no difference between the groups with respect to PSA decrease at 12 weeks after treatment initiation or median progression-free survival. However, patients who received the lower dose were older than those receiving standard dosing, had a poorer performance status, and were more heavily pre-treated. Further studies would be needed to support routine use of lower dose enzalutamide.”

Mark Klein, MD