INTRODUCTON: We studied the effect of dutasteride on the length of the off-treatment period in prostate cancer patients on intermittent androgen deprivation (IAD) therapy.
METHODS: We conducted a randomized, placebo-controlled Phase II trial in men with localized prostate cancer and a rising prostate-specific antigen (PSA) level post-primary treatment. Patients were randomized to dutasteride (0.5 mg/day) or placebo. All patients received androgen deprivation therapy (ADT), which was stopped at month 9 if the PSA level was < 1.0 ng/mL. ADT was resumed when PSA increased to ≥5.0 ng/mL. End points included time off treatment, PSA nadir after 9 months of ADT, serum testosterone and dihydrotestosterone levels, and time to castrate-resistant prostate cancer (rising PSA while testosterone levels remain < 50 ng/mL).
RESULTS: There were 87 evaluable patients: 49 dutasteride, 38 placebo. In total, 80 patients completed one treatment cycle: 45 dutasteride, 35 placebo. The median time off treatment for patients reaching ≥5 ng/mL was 18.6 and 16.7 months for dutasteride and placebo, respectively (p = 0.7600). The median PSA nadir at 9 months was 0.1 and 0.075 ng/mL, respectively (p = 0.4486). There were no cases of androgen-independent prostate cancer. Our study limitations include its short duration with only one treatment cycle evaluated.
CONCLUSIONS: This small-scale Phase II randomized controlled trial showed no benefit to the addition of dutasteride to an IAD regimen.
Klotz L, Nabid A, Higano C, Ryanm C, Kebabdjian M, Chin J. Are you the author?
Division of Urology, Sunnybrook Health Sciences Centre, Toronto, ON; Department of Radiation Oncology, Centre Hospitalier de Universitaire de Sherbrooke, Sherbrooke, QC; Departments of Medicine and Urology, University of Washington Seattle Cancer Care Alliance, Seattle, WA; Department of Medicine, Oregon Health Sciences University, Portland, OR; Division of Urology, London Health Sciences Centre, London, ON.
Reference: Can Urol Assoc J. 2014 Nov;8(11-12):E789-94.