Perceptions of emerging PARP inhibitor (PARPi) data among practicing oncologists in prostate cancer.

546 Background: Studies suggest that PARPi agents work best in cancers, including metastatic castration-resistant prostate cancer (mCRPC), that have mutations in DNA repair pathways regulated by homologous recombination repair ( HRR) genes . The first PARPis for prostate cancer (olaparib for HRR-mutated and rucaparib for BRCA-mutated CRPC) were approved in 2020. Two recent trials, TALAPRO-2 and PROpel, evaluate PARPis plus an androgen receptor pathway inhibitor for patients both with and without genetic mutations were presented at ASCO GU 2023. This study aimed to determine oncologists’ perceptions of these new data. Methods: In April 2023, US-based oncologists were invited to attend one of two meetings to discuss data from ASCO GU 2023. Demographics were collected in an online survey, and perceptions of the TALAPRO-2 and PROpel trials were captured via audience response system technology at the meetings. Results: Across the two meetings, 115 oncologists were surveyed; 99 oncologists (86%) indicated that they manage patients with prostate cancer. Of these, 74% reported that they either very often or always test for HRR mutations, and the majority are testing at initial diagnosis of metastatic disease. Prior to reviewing trial updates, 84% of oncologists reported olaparib as their preferred PARPi, and the top factors driving their preferences are efficacy (83%) and safety/tolerability (63%). Perceptions of the trial updates are reported in Table 1. A subset of oncologists were also asked their treatment preferences for patients with mCRPC before and after the trial updates. Altogether, there was a 41% increase in physicians who would use talazoparib plus enzalutamide in an ATM-mutated patient after progression on docetaxel. They were also more likely to report (35%) a preference for this combination for a BRCA1-mutated patient after progression on abiraterone acetate. Additionally, there was a 27% increase in physicians who would use olaparib plus abiraterone acetate in an HRR-wild type patient after enzalutamide. Conclusions: Overall, these data show that clinical updates regarding PARPi agents have an impact on practicing oncologists. However, further exploration of genetic testing practices among oncologists and the impact of emerging data on real-world practice is needed.[Table: see text]