Abstract IA17: PARP inhibition modulates the tumor immune microenvironment in Brca1-deficient ovarian tumor

Abstract

Abstract Poly ADP ribose polymerase (PARP) inhibitors have shown promising clinical activities for patients with BRCA mutations and are changing the landscape of ovarian cancer treatment. However, the therapeutic mechanisms of action for PARP inhibition in the interaction of tumors with the tumor microenvironment and the host immune system remain unclear. We recently reported that inhibition with a PARP inhibitor (olaparib) triggers robust local and systemic antitumor immunity involving both adaptive and innate immune responses through a STING-dependent antitumor immune response in Brca1-deficient ovarian tumors. This effect is further augmented when olaparib is combined with PD-1 blockade. However, all PBM-bearing mice treated with olaparib alone or in combination with PD-1 blockade eventually succumbed to the disease. These data indicate that although multiple PARP inhibitors have been approved for the treatment of BRCA-deficient ovarian cancers, eradication of this type of cancer remains a challenge. I will discuss our recent efforts on identifying resistance mechanisms to PARP inhibition and developing potential therapeutic strategy that overcomes the resistance to improve the treatment outcome. Citation Format: Liya Ding, Qiwei Wang, Michael Kearns, Tao Jiang, Panagiotis Konstantinopoulos, Ursula Matulonis, Jean Zhao. PARP inhibition modulates the tumor immune microenvironment in Brca1-deficient ovarian tumor [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr IA17.