Abstract 1829: Olaparib antiproliferative effect in pancreatic cancer and correlation with the response to other anticancer agents

Abstract AstraZeneca obtained positive results from POLO, the first Phase III randomised, double-blind study that evaluated the efficacy of the PARP inhibitor (PARPi) olaparib, for maintenance monotherapy in patients with gBRCA mutated metastatic pancreatic cancer whose disease has not progressed on first-line platinum-based chemotherapy. To support the application of olaparib for the proposed indication in these patients, a series of in vitro pharmacological tests were performed and will be here presented. 1. In a panel of pancreatic cancer cell lines, a striking correlation was observed between the responses to platinum and to olaparib. This indicates that it is predictable that olaparib will show efficacy in treatment of platinum-sensitive pancreatic cancer, as it has been previously demonstrated in other cancer indications. 2. Tests in isogenic cell line pairs and non-tumour cell lines revealed that platinum treatments lead to cytotoxic effects that are only ~10-20-fold more selective for BRCAm versus BRCAwt and non-tumour models; in contrast, olaparib is able to selectively kill BRCAm cells, with ~500-1000-fold sensitivity versus the BRCAwt cells. 3. In the panel of pancreatic cancer cells, the sensitivity to other DNA damaging agents used as standard of care, such as irinotecan (and, to some extent, 5FU, other key components of FOLFIRINOX as well as gemcitabine), correlated with sensitivity to olaparib. In contrast, no correlation was observed with paclitaxel (mitotic inhibitor), or with other agents. 4. The antiproliferative effects to olaparib treatments in the cancer cell panel were compared to that of other 5 clinical PARPi. High correlations were observed in the responses to all the PARPi except for veliparib, which inhibits the catalytic activity of PARP but does not act as PARP-trapper, confirming that the efficacy of PARPi in monotherapy depends on their ability to stabilise the interaction between PARP and the DNA. Citation Format: Elisabetta Leo, Giuditta Illuzzi, Sabrina Bentouati. Olaparib antiproliferative effect in pancreatic cancer and correlation with the response to other anticancer agents [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1829.