Apalutamide: A new agent in the management of prostate cancer

Apalutamide is a competitive inhibitor of the androgen receptor and binds directly to the ligand-binding domain. The US Food and Drug Administration approved apalutamide on 14 February 2018 for use in patients with nonmetastatic castration-resistant prostate cancer based upon results from the phase III SPARTAN trial demonstrating significantly longer metastasis-free survival over placebo. The SPARTAN trial evaluated 1207 patients with nonmetastatic castration-resistant prostate cancer who were randomized 2:1 to apalutamide or placebo in combination with androgen deprivation therapy. Patients who received apalutamide experienced statistically significantly longer metastasis-free survival (40.5 versus 16.2 months, hazard ratio 0.28 (95% confidence interval = 0.23-0.35); P < 0.0001), which was the major efficacy outcome. Rash, hypothyroidism, and fracture were reported to occur more frequently with apalutamide than placebo. Based upon these results, apalutamide was deemed a safe and effective treatment option for patients with nonmetastatic castration-resistant prostate cancer. Clinical trials are ongoing to expand its indication in the metastatic setting, and identify additional roles for apalutamide in the management of prostate cancer such as in the castrate-sensitive metastatic setting.