Rezvilutamide plus docetaxel in chemotherapy-naive metastatic castration-resistant prostate cancer patients after progression on abiraterone: A multi-centre, open-label, phase II trial.

BACKGROUND

A multi-centre, 2-part, phase II study assessed adding rezvilutamide (a novel androgen receptor antagonist) to docetaxel in abiraterone-refractory, metastatic castration-resistant prostate cancer (mCRPC) patients who were naive to chemotherapy. Herein, we report results from part 1.

METHODS

Part 1 encompassed both dose-escalation and dose-expansion phases. Eligible patients received oral rezvilutamide (160/240 mg, once daily [QD]) plus intravenous docetaxel (75 mg/m2, on the first day of every 3-week cycle) for more than 10 cycles, followed by maintenance with rezvilutamide monotherapy (240 mg, QD). Rezvilutamide was administered daily starting from the second day of cycle 1. Docetaxel was co-administered with oral prednisone at 5 mg twice daily. Safety served as the primary objective in Part 1.

RESULTS

From 2, December 2020, to 5, August 2021, 36 patients were eligible for enrolment (18 patients with rezvilutamide 160 mg plus docetaxel and 18 patients with rezvilutamide 240 mg plus docetaxel). No one experienced dose-limiting toxicity. 32 (88.9%) patients experienced grade 3 or higher treatment-related adverse events. At week 12, 67.7% of the 31 evaluable patients showed a response in prostate-specific antigen (PSA) levels. Among all 36 patients, the median times were 10.5 months (95% CI: 5.6-14.1) for PSA progression, 13.8 months (95% CI: 8.4-19.2) for radiological progression-free survival and 16.2 months (95% CI: 12.9-22.5) for overall survival. The limitations were a small sample size and a non-randomised design.

CONCLUSIONS

Rezvilutamide plus docetaxel followed by maintenance with rezvilutamide monotherapy demonstrated good tolerability and promising efficacy in chemotherapy-naive, abiraterone-refractory, mCRPC patients.