The purpose of this study is to compare the efficacy of ASP4901 with placebo in patients with benign prostatic hyperplasia. The safety and tolerability of ASP4901 will also be evaluated.

This is a multicenter, randomized, parallel-group, placebo-controlled, active-referenced, double-blind study. After obtaining the written consent, patients meeting the eligibility criteria at the preliminary enrollment will receive oral administration of placebo in a single-blinded manner (single-blind placebo run-in period). Then, patients meeting the eligibility criteria at the main enrollment will receive drug or placebo (double-blind treatment period) for 4 weeks. Furthermore, patients will be followed up for 1 week to confirm the safety of the study drugs after the treatment period (safety follow-up period).

Inclusion Criteria:

• dysuria associated with BPH for at least 12 weeks before providing consent
• a total IPSS core of 13 or higher
• a QOL score of 3 or higher
• a maximum urinary flow rate (Qmax) of ≥4 mL/sec and <15 mL/sec.
• a prostate volume of ≥20 mL.

Exclusion Criteria:

• A postvoid residual volume (PVR) of >350 mL
• A previous or concurrent symptomatic urinary tract infection within 4 weeks of the study
• A cataract operation scheduled to be performed during the study period
• Previous or concurrent clinically relevant cardiovascular or cerebrovascular disorder within 24 weeks prior to the study
• Hypersensitivity to ASP4901 or tamsulosin hydrochloride
• Presence of serious hepatic diseases, renal diseases, immunological diseases, or pulmonary diseases that are clinically relevant

Access to anonymized individual participant level data will not be provided for this trial. Further details on Astellas' data sharing policy can be found at https://www.clinicaltrials.astellas.com/transparency/.