DSP-0692, a selective SCD inhibitor, enhances the anti-tumor activity of anti-PD1 antibody

SCD (Stearoyl-CoA Desaturase), a key enzyme for lipid metabolism, is overexpressed in various types of cancer and plays an important role in cancer cell proliferation. We have previously shown that the identification and the functional characterization of DSP-0692, a novel and selective SCD inhibitor. SCD expression was induced in tumor cells cultured in sphere conditions, which were resistant to conventional agents within therapeutic concentration. DSP-0692 showed strong growth inhibition when tumor cells were cultured in sphere conditions, but had little impact on cells cultured under adherent conditions. In addition, DSP-0692 decreased the expression of stemness-related genes in tumor cells as well as in tumor tissues. Treatment with DSP-0692 suppressed tumor growth in multiple models both in single agent or in combination with conventional chemotherapies. DSP-0692 also inhibited WNT/beta-catenin signaling pathway through two different mechanisms (inhibition of Wnt3A secretion and nuclear translocation of beta-catenin). DSP-0692 exhibited lower IC50 value to sphere cells carrying mutations related to WNT/beta-catenin signaling pathway than those without these mutations. Blockade of the coinhibitory checkpoint molecule PD-1 has emerged as an effective treatment for many cancers. However, despite successes in the clinical setting, only a limited subpopulation respond to PD-1 blockade. We hypothesized that the deregulated lipid metabolism of tumor cells and microenvironment function as a barrier to antitumor immunity, and therefore that normalization of lipid metabolism with DSP-0692 might restore response to immunotherapy. Combination of DSP-0692 with anti-PD-1 antibody in the syngeneic CT-26 colon model, a resistant model to anti-PD-1 antibody, augmented tumor regressions relative to each single agent alone. DSP-0692 induced PD-L1 and PD-L2 expression in CT-26 cells, indicating that it is one of a mechanism of restoration of the effect of anti-PD-1 antibody. Our data suggest that remodeling the lipogenic tumor microenvironment has potential to convert patients resistant to immunotherapy into those who may receive clinical benefit of immunotherapy. Citation Format: Eiji Sugaru, Yudai Furuta, Yoshikazu Nagagaki, Satoshi Ikeda, Yuichi Fukunaga, Hiroki Umehara, Tsuguteru Otsubo, Manabu Watanabe, Shingo Tojo, Miki Hashizume, Yasushi Matsuki, Hitoshi Ban. DSP-0692, a selective SCD inhibitor, enhances the anti-tumor activity of anti-PD1 antibody [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3595.