LAUSR

Prostaglandin E2 (PGE2) contributes to immunosuppression in the tumor microenvironment through one or more of its receptors (EP1-EP4), especially EP4 which is expressed at high levels on myeloid cells. ONO-4578/BMS-986310 is a novel EP4-selective antagonist that potently inhibits the PGE2-induced cAMP production in CHO cells expressing mouse and human EP4 receptors with single-digit nM IC50. Furthermore, ONO-4578/BMS-986310 shows excellent pharmacokinetic properties after oral dosing in mouse. ONO-4578/ BMS-986310 reverses PGE2-mediated suppression of T cell activation and promotes DC differentiation in vitro. Moreover, treatment with ONO-4578/BMS-986310 inhibits growth of CT26 and MC38 tumors in syngeneic mouse. The anti-tumor effect of ONO-4578/BMS-986310 is abrogated in immuno-deficient mice bearing CT26 tumors indicating that such effect is immune-mediated. ONO-4578/BMS-986310 treatment significantly prolongs survival of mice with highly aggressive SB28 gliomas in the brain. Flow cytometric analysis reveals that ONO-4578/BMS-986310 reduces infiltration of M2 macrophages in MC38 tumors compared with control mice. Microarray analysis of MC38 tumor tissues demonstrates up-regulation of cytotoxic T lymphocytes, natural killer cells and innate immunity-related genes after treatment with ONO-4578/BMS-986310. Finally, a combination of ONO-4578/BMS-986310 and anti-PD-1 antibody results in enhanced anti-tumor effects in GL261 and MC38 tumor-bearing mice compared with anti-PD-1 monotherapy.Our data demonstrate that ONO-4578/BMS-986310 promotes anti-tumor immunity and may be useful in the treatment of cancer patients. ONO-4578/BMS-986310 is being evaluated as monotherapy and in combination with nivolumab in an ongoing Ph1/1b clinical trials in patients with advanced solid tumors (NCT03155061, NCT03661632). Citation Format: Tohru Kotani, Hirotsugu Takano, Tomoko Yoshida, Ryota Hamasaki, Gary Kohanbash, Kazuhiko Takeda, Hideho Okada. Inhibition of PGE2/EP4 pathway by ONO-4578/BMS-986310, a novel EP4 antagonist, promotes T cell activation and myeloid cell differentiation to dendritic cells [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 4443.