Cellular transporters as novel metabolic immune checkpoints: NGY-091, a small molecule dual MCT1/4 inhibitor for immuno oncology

Background: Aberrant metabolic reprogramming of malignant cells is known to drive cancer progression and metastasis. The increase in glycolytic flux in cancer cells creates a lactate-rich tumor microenvironment (TME), which tumors exploit by expanding immunosuppressive cell populations such as Tregs and MDSCs that thrive on lactate as a fuel source. Blockade of lactate export from glycolytic cancer cells, while inhibiting lactate uptake by suppressive immune cells, is a novel therapeutic strategy to treat cancer. Lactate transport in cells is predominantly mediated by MCT1 and MCT4 transporters. We have developed a compound, NGY-091, a first-in-class small molecule dual inhibitor of the MCT1 and MCT4 lactate transporters. Materials and Methods: The direct cytotoxic effect of NGY-091 was examined in multiple cancer cell lines. The on-target activity of NGY-091 was validated by measuring intracellular and extracellular lactate levels. in vivo efficacy of NGY-091 was studied using CDX, PDX and syngeneic tumor models. Immune profiling of tumor was performed 2 weeks after treating animals with NGY-091 by flow cytometry. Results: NGY-091 treatment exhibited a potent in vitro cytotoxicity against cancer cells with various levels of MCT1 and MCT4 expressions. NGY-091 strongly blocked lactate import through MCT1 under high lactate conditions and lactate export through MCT4 in high glucose conditions. NGY-091 treatment also inhibited pyruvate entry into the mitochondria through MPC1. Furthermore, direct in vivo tumor cell killing was evident in multiple human CDX and PDX models with the treatment of NGY-091. In syngeneic models of 4T1 and MC38 murine tumors, we observed significant tumor growth inhibition with NGY-091 treatment, and strong synergistic tumor reduction when treatment was combined with various immune checkpoint inhibitors. Profiling of lymphoid and myeloid cells in NGY-091 treated tumors by flow cytometry revealed a significant alteration in immune architecture suggesting activation of antitumor immunity. NGY-091 treated tumors induced a profound increase in effector T cell populations, CD8/Treg ratio, and tumor-suppressive M1 macrophages, while significantly downregulating M2 macrophages. To further investigate if NGY-091 directly alters immune cell activation and functionality in vitro, we treated CD4 T, CD8T, Tregs, and MDSCs in a lactate-rich culture condition, which mimicked the lactate level in the TME. NGY-091 treatment strongly increased effector CD4+ and CD8+ T cells, meanwhile it significantly reduced suppressive function of Treg and MDSCs in vitro. Conclusions: These findings indicate the direct effect of NGY-091 on immune cells and validate the in vivo observations in 4T1 tumors. Therefore, NGY-091 intervenes with two key hallmarks of cancer, metabolism and immunity and provides a novel modality to therapeutically target cancer. Conflict of interest: Ownership: Nirogy Therapeutics