Efficacy and safety of apalutamide in patients with metastatic castration-resistant prostate cancer (GENESIS): protocol for a multicentre, open-label, single-arm clinical trial

INTRODUCTION: This is a multicentre, open-label, single-arm clinical trial to evaluate the efficacy and safety of apalutamide in patients with metastatic castration-resistant prostate cancer. METHODS AND ANALYSIS: The trial will be performed at 4 university hospitals and 14 city hospitals in Japan. The target number of patients will be 110. The patients will be orally administered 240 mg apalutamide once daily during the treatment period. The primary outcome is the prostate-specific antigen (PSA) response rate. PSA response is defined as ≥50% decline from baseline at 12 weeks. Secondary outcomes are time to PSA progression, progression-free survival, overall survival, progression-free survival during second therapy, ≥50% decline in PSA from baseline at 24 and 48 weeks, ≥90% decline in PSA from baseline or lower PSA detection sensitivity after the initial dose at 12, 24 and 48 weeks, PSA maximal changes, accumulated PSA response from screening to 24 and 48 weeks, and grade 3 or 4 adverse events according to the Common Terminology Criteria for Adverse Events version 4.0. ETHICS AND DISSEMINATION: This study has been approved by the Certified Research Review Board of Kobe University (No. CRB5180009). All participants will be required to provide written informed consent. Findings will be disseminated through scientific and professional conferences and peer-reviewed journal publications. The datasets generated during the study will be available from the corresponding author on reasonable request. TRIAL REGISTRATION NUMBER: jRCTs051220077.