Abstract B029: Incidence of grade II or higher hematologic toxicities in ovarian cancer patients on concurrent poly-ADP ribose polymerase inhibitor therapy and anti-Xa inhibition therapy

Abstract Background: Ovarian cancer (OC) is the most lethal gynecologic malignancy and poly-ADP ribose polymerase inhibitors (PARPi) are commonly used in the maintenance setting for homologous recombination deficient cancers. Toxicity of PARPi is low compared to traditional chemotherapies, but they are associated with hematologic toxicities including anemia, thrombocytopenia, and neutropenia. Coincidentally, because of the hypercoagulable state of malignancy, many OC patients are on concurrent PARPi and factor Xa inhibitors due to a history of venous thromboembolism. Objective: This study aims to characterize and quantify PARPi therapy adjustments in OC patients on factor Xa inhibitors (PARPi+AC) compared to patients not on concurrent factor Xa inhibition (PARPi only). Methods: This was a single-institution retrospective cohort study on OC patients from November 2017 to June 2024. Patients were identified using an institutional pharmacy database. OC patients were included if they received PARPi for >6 months or if they experienced any grade II or higher hematologic toxicity on PARPi. PARPi + AC cohort included patients on factor Xa inhibition at any time while on PARPi. Results: 165 patients were identified during the study period. PARPi+AC cohort included 18.8% of patients (n=31), 81.2% (n=134) of patients in PARPi only cohort. Incidence of grade II or higher anemia in PARPi+AC group was 22.58% (n=7) vs PARPi only 20.9% (n=28) (p = 0.811). Incidence of grade II or higher thrombocytopenia in PARPi+AC was 32.26% (n=10) vs PARPi only 20.15% (n=27) (p = 0.145). Incidence of therapy interruptions for grade II or higher neutropenia in PARPi+AC was 12.9% (n=4) vs PARPi only 8.21% (n=11) (p = 0.486). Incidence of therapy interruptions for any grade II or higher hematologic toxicity in PARPi+AC was 45.16% (n=14) vs PARPi only 22.39% (n=30) (p = 0.009). Conclusion: Patients on PARPi and factor Xa inhibition concurrently may experience more PARPi therapy interruptions for grade II or higher hematologic toxicities compared to PARPi alone. Citation Format: Julia Taylor, Miranda Benfield, Zahra Bahrani-Mostafavi, Kelley Kaczmarski, Allison Puechl. Incidence of grade II or higher hematologic toxicities in ovarian cancer patients on concurrent poly-ADP ribose polymerase inhibitor therapy and anti-Xa inhibition therapy [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Ovarian Cancer Research; 2025 Sep 19-21; Denver, CO. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl):Abstract nr B029.