This study consists of two parts. The purpose of PART 1 is to test non-inferiority of ASP3550 to goserelin acetate with respect to the cumulative castration rate in terms of serum testosterone when ASP3550 or goserelin acetate is administered for one-year in patients with prostate cancer.~The patients assigned to receive ASP3550 and completed the treatment in PART 1 are eligible for the treatment in PART 2, and will receive ASP3550 maintenance dose subcutaneously for additional term. The long-term safety, efficacy and PK of the continued ASP3550 treatment will be assessed in PART 2.
To compare the efficacy and safety of ASP3550 to goserelin acetate in patients with prostate cancer.