Enzalutamide shows long-term antitumour activity in hormone-naïve prostate cancer
Enzalutamide demonstrates antitumour activity for up to 3 years in patients with hormone-naïve prostate cancer, according to a follow-up analysis of a phase II trial. Specifically, results for bone mineral density, global health status and safety at year 3 are similar to those at year 2.
The open-label trial included 67 hormone-naïve prostate cancer patients with noncastrate testosterone (≥230 ng/dL). All patients were given enzalutamide 160 mg/day orally until disease progression or unacceptable toxicity. Prostate-specific antigen (PsA) response (≥80 percent decline from baseline) was investigated as the primary endpoint.
All patients persisted with their treatment at year 3, and 90.5 percent of the 42 patients with PsA data available during this period maintained a PsA response. Of the 26 patients with metastases at baseline, 65.4 percent showed complete or partial response as the best overall response over 3 years.
The 3-year visit data revealed marginal mean changes from baseline in total body bone mineral density or bone mineral density of the femoral neck, trochanter, spine L1 to L4 or forearm (range, -2.7 to -0.1 percent). Total body fat increased by 16.5 percent, while total lean body mass fell by -6.5 percent. There was a slight decrease in global health status from baseline.
Safety results remained favourable at 3 years. Commonly reported adverse events included gynecomastia, fatigue, hot flush and nipple pain.
An oral androgen receptor signalling inhibitor approved for treating patients with metastatic castration-resistant prostate cancer, enzalutamide acts by inhibiting the binding of androgens to the androgen receptor, androgen-receptor nuclear translocation and androgen receptor-mediated DNA binding. [N Engl J Med 2014;371:424; Lancet Oncol 2016;17:153; Science 2009;324:787]