A Study to Compare the Effect of ASP3550 With Goserelin in Patients With Prostate Cancer

Inclusion Criteria: * Male patient with histologically confirmed prostate cancer (adenocarcinoma). * Patient in whom endocrine treatment is indicated. Patient having undergoing prostatectomy or radiotherapy with curative intention and has a rising serum PSA (PSA ≥ 2 ng/mL at screening) may be included. * Has a serum testosterone level above 2.2 ng/mL at screening. * Has an Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) score of 0 to 2 at screening. * Has a serum PSA ≥ 2 ng/mL at screening. * Has a life expectancy of at least 12 months. Exclusion Criteria: * Previous or present endocrine treatment for prostate cancer. Example: surgical castration, GnRH agonists, GnRH antagonists, antiandrogens or oestrogens, and 5α-reductase inhibitors. * Received a 5α-reductase inhibitor within 25 weeks preceding screening. * Is a candidate for curative therapy, i.e., radical prostatectomy or radiotherapy within 12 months. * Has concurrent or a history of poorly controlled severe asthma, anaphylactic reactions, severe urticaria or angioedema. * Has hypersensitivity towards mannitol. * Has a marked prolongation of QT/QTc interval (two consecutive increases to \>450 ms in QTc interval at retest) at screening. * Has concurrent or a history of a disease (heart failure, hypokalemia, a family history of QT prolongation syndrome, etc.) that may induce Torsade de Pointes.