Olaparib (Lynparza) and rucaparib (Rubraca) are both PARP inhibitors approved for mCRPC patients following AR therapy. Olaparib was the first PARP inhibitor approved, allowing it to gain a lead in the market, after the patients in the treatment arm of the Phase III PROpel trial achieved a median OS of 19.1 months and an rPFS of 5.8 months in the overall homologous recombination repair deficient cohort. Rucaparib received approval following positive results from the Phase II TRITON2 trial, where patients with measurable disease and BRCA mutations achieved a median ORR of 43.5% after rucaparib treatment.
Two other PARP inhibitors are currently in development for prostate cancer: talazoparib (Talzenna) and niraparib (Zejula). Neither therapeutics have late-phase data available in this indication, but talazoparib -treated patients with BRCA mutations in the Phase II TALAPRO-1 trial showed an rPFS of 9.3 months, whilst niraparib-treated patients had an rPFS of 8.2 months and an OS of 12.6 months in the Phase II GALAHAD trial.
Share your thoughts on the efficacy shown by both talazoparib and niraparib, and based on this data, if either drug is approved, how would this likely change your prescribing practices?