Abstract ED12-3: ATR inhibitors and PARP1 selective PARP inhibitors

Abstract

Abstract The targeting of Homologous Recombination deficient (HRD) malignancy using a synthetic lethal strategy based on the inhibition and trapping of PARP1 on DNA in manner that leads to tumour selective effects via dependency on the function of HR gene products such as BRCA1, BRCA2 and PALB2 for DNA replication fitness is now well established. However, there is a need to improve both the frequency and duration of response in the licensed indications and to explore combination PARP inhibitor (PARPi) strategies that may be effective a broader range of breast cancers with functional deficiencies in HR and the wider DNA damage response. ATR inhibitors exacerbate replication stress that is toxic to HR deficient cells. Combinations of an ATR inhibition (ATRi) and PARPi have been shown to be synergistic and to be active in PARPi resistant pre-clinical model contexts. The development of combination strategies of these agents and of platinums and ATRi have been limited by combinatorial toxicity but have recently reported results in breast cancer. PARP1 is part of a family of PARP enzymes and currently licensed PARPi inhibit several family members that underpin some of their toxicity. New PARP1 selective agents have recently reported results in early phase trials. I will review some of the mechanistic rationale, preclinical data and relevant clinical trial data in my lecture. Citation Format: Andrew Tutt. ATR inhibitors and PARP1 selective PARP inhibitors [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr ED12-3.