Rucaparib Boosts PFS Across Germline and Somatic BRCA-Mut mCRPC in TRITON3

Rucaparib, an oral PARP inhibitor, was compared with physician’s-choice docetaxel or abiraterone/enzalutamide in the Phase 3 TRITON3 trial (NCT02975934) in the ~13% of patients with BRCA deficient metastatic castration-resistant prostate cancer. In the rucaparib arm, 201/270 patients had BRCA mutations, and in the physician’s choice arm, 101/135 patients had BRCA mutations, split roughly 40% germline and 60% somatic. Radiographic PFS favored rucaparib regardless of mutation origin—HR 0.52 (95% CI 0.32–0.84) in germline (n = 80 vs. 39) and HR 0.38 (0.25–0.59) in somatic (n = 116 vs. 48)—with similar Grade ≥3 adverse-event rates between germline and somatic subsets.