According to data from the Phase 3 trial, rucaparib significantly improved the radiographic progression-free survival (rPFS) compared with either docetaxel or abiraterone/enzalutamide among patients with metastatic castration-resistant prostate cancer. Additionally, the results suggest an improvement in overall survival (OS) with rucaparib for patients with BRCA alterations.

Alan Haruo Bryce, MD, Mayo Clinic, Phoenix, AZ, presented interim data from the phase 3 study on Thursday, February 16, 2023, at the 2023 ASCO Genitourinary Cancers Symposium in San Francisco, CA.

In the multicenter, open-label TRITON3 study, 405 patients were randomized on a 2-to-1 basis to receive either 600 mg rucaparib twice daily (n = 270) or physician’s choice (docetaxel, n = 75; or abiraterone or enzalutamide, n = 60). There was a total of 302 patients with BRCA and 103 patients with ATM alterations randomized. Previous results from the trial demonstrated rucaparib significantly improved rPFS compared with physician’s choice among patients with BRCA or ATM alterations. The primary end point of rPFS was also examined among the intent-to-treat population. A key secondary end point was overall survival.

The median rPFS with rucaparib was 10.2 months, compared with 8.3 monthes with docetaxel (hazard ratio [HR], 0.80; 95% confidence interval [CI], 0.58 to 1.11; P = .2013) and 4.5 months with abiraterone/enzalutamide (HR, 1.01; 95% CI, 0.70 to 1.46; P = .9045). The median OS for patients with BRCA alternations in the rucaparib arm was 24.3 vs 20.8 in the docetaxel group (HR, 0.75; 95% CI, 0.51 to 1.11; P = .1640), and vs abiraterone/enzalutamide (HR, 0.81; 95% CI, 0.52 to 1.27; P = .4023).

The most common treatment-emergent adverse event overall was asthenia/fatigue. The most common ≥3 event was anemia in the rucaparib arm, neutropenia in the docetaxel arm, and hypertension in the abiraterone/enzalutamide arm.

Dr Bryce and coauthors concluded, “rucaparib significantly improved rPFS vs either [docetaxel or abiraterone/enzalutamide]; safety is consistent with prior reports,” adding, “interim OS results suggest a trend towards improvement for rucaparib vs [docetaxel or abiraterone/enzalutamide]” among patients with BRCA alterations.

Source:

Bryce AH, Piulats JM, Reaume MN, et al. Rucaparib for metastatic castration-resistant prostate cancer (mCRPC): TRITON3 interim overall survival and efficacy of rucaparib vs docetaxel or second-generation androgen pathway inhibitor therapy. Presented at 2023 ASCO Genitourinary Cancers Symposium; February 17-19; San Francisco, CA. Abstract 18