Enzalutamide (Xtandi) for Patients With Metastatic,Resistant Prostate Cancer

Objective: To review the pharmacology and pharmacokinetics, and to evaluate the clinical efficacy, safety, and place in therapy of enzalutamide for the treatment of castration-resistant prostate cancer (CRPC). Data Sources: A literature search through PubMed (1984 to November 2013; English language) was performed using the following keywords: MDV3100, androgen deprivation therapy, enzalutamide, CRPC, and androgen receptor antagonist. Searches were limited to published studies in humans. Study Selection and Data Extraction: All articles in English identified from reviews, abstracts, presentations, and clinical trials of enzalutamide in humans were selected and included. Data Synthesis: Enzalutamide is an oral, nonsteroidal second-generation androgen receptor antagonist that is Food and Drug Administration–approved for the treatment of metastatic CRPC in men who were previously treated with docetaxel. Enzalutamide was superior to placebo for increasing median survival from 13.6 months to 18.4 months. Enzalutamide was well tolerated at a dose of 160 mg, with minor adverse events such as fatigue, diarrhea, musculoskeletal pain, and hot flashes. Patients with increased risk of seizure should not take enzalutamide. Conclusions: Enzalutamide is effective to slow progression of metastatic CRPC, to reduce prostate-specific antigen (PSA) levels, to decrease time to progression of PSA, to increase time to first skeletal-related events, and to increase quality of response rate. Enzalutamide was given at 160 mg/d for a median of 8 cycles of administration. Clinical trials are currently being conducted to observe if enzalutamide will be useful for treatment of other cancers and for early administration in prostate cancer.