Neoadjuvant/adjuvant relugolix and enzalutamide for the treatment of high-risk locally advanced prostate cancer: study protocol of the RENAPCA phase Ib trial

Introduction Treatment for high-risk locally advanced prostate cancer typically includes radiation or radical prostatectomy plus androgen deprivation therapy (ADT), but the optimal use of neoadjuvant and adjuvant ADT in practice remains unclear. Relugolix and enzalutamide have demonstrated strong efficacy independently in the setting of advanced disease, but their combined use in neoadjuvant/adjuvant therapy has not been studied. This trial investigates their safety and efficacy as neoadjuvant/adjuvant therapy in patients undergoing definitive local treatment. Methods and analysis Relugolix and Enzalutamide as Neoadjuvant/Adjuvant to Local-regional treatment in Patients with High-risk, Locally Advanced Prostate Cancer (RENAPCA) is a prospective, single-arm, open-label phase Ib trial with blinded outcome assessment. The study is conducted across four tertiary oncology centres within the United States. Eligible participants are adult men with pathologically confirmed locally advanced high-risk prostate cancer who are candidates for definitive local therapy. Patients with significant comorbidities or a life expectancy of less than 6 months are excluded. The trial includes a 3+3 dose-escalation safety lead-in cohort (up to 12 patients) to determine dose-limiting toxicities and recommended phase 2 dose, followed by a dose expansion cohort (up to 46 patients). Interventions consist of 6 months of neoadjuvant therapy with relugolix plus enzalutamide, definitive local therapy (radical prostatectomy or radiation therapy), and 18 months of adjuvant therapy with relugolix plus enzalutamide. Primary outcomes include pathologic CR rate and minimal residual disease rate. Secondary outcomes include prostate-specific antigen response, progression-free survival, objective response rate, frequency and severity of adverse events, and positive margin/pathologic downgrade rate. Exploratory objectives include patient-reported outcomes and quality of life measures. RENAPCA will assess the safety and efficacy of neoadjuvant/adjuvant relugolix+enzalutamide in high-risk, locally advanced prostate cancer to support future larger-scale studies and potentially improve treatment outcomes. Ethics and dissemination This research protocol has been approved by the Institutional Review Board of the University of Oklahoma Health Sciences Center (7 March 2024). The study is based on voluntary participation with informed written consent. Trial registration number NCT06130995 .