Enzalutamide monotherapy: Extended follow-up of a phase II study in hormone-naive prostate cancer patients.

62 Background: The efficacy and safety of enzalutamide (ENZA) monotherapy was assessed in hormone-naive men with prostate cancer (PC; any stage) eligible for androgen-deprivation therapy (ADT). The primary end point of prostate-specific antigen (PSA) response rate (80% or more decline), assessed at 25 weeks (wks), was 92.5% with a median (range) maximum decrease of –99% (–100, –86.5) (Tombal et al. ASCO-GU 2013). Here we present data from the extended follow-up at 49 wks. Methods: In an open-label, single-arm phase II study, men age 18 or older with histologically confirmed PC requiring ADT, non-castrate testosterone (8 nmol/L or more), PSA 2 ng/mL or more at screening and a life expectancy of 12 months or more, received 160 mg ENZA once daily (NCT01302041). Treatment continued until disease progression or unacceptable toxicity. Secondary end points included changes in endocrine levels, metabolic parameters, bone mineral density (BMD), quality of life, and safety. Results: Sixty seven men were enrolled. M...