Abstract P3-07-21: Therapeutic efficacy of NGY-091 against triple negative breast cancer is mediated by direct cell killing and activation of antitumor immunity
Authors: Sharma Sambad , Wijerathna Sanath , Wu Kerui , Tyagi Abhishek , Wu Shih-Ying , Watabe Kounosuke , Kuklin Nelly , Escobedo Jaime , Sandanayaka Vincent 
Published: March 2023

Abstract
Aberrant metabolic reprogramming is known to drive triple negative breast cancer progression and metastasis. The increase in glycolytic flux in cancer cells creates a lactate-rich tumor microenvironment (TME) that is exploited by tumors to their advantage by activating immunosuppressive cell populations, such as Tregs and MDSCs, that thrive on lactate as a fuel source. Therefore, blockade of lactate export from glycolytic cancer cells while inhibiting lactate entry into 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, that is a first-in-class small molecule dual inhibitor of the MCT1 and MCT4 lactate transporters. NGY-091 treatment exhibited a potent in vitro cytotoxicity against breast cancer cells with various levels of MCT1 and MCT4 expressions. The on-target activity of NGY-091 was validated by measuring intracellular and extracellular lactate levels. NGY-091 strongly blocked MCT1 mediated lactate import and lactate export through MCT4 in vitro. Furthermore, a direct in vivo tumor cell killing was evident in human TNBC CDX (MDA MB 231) and PDX models with the treatment of NGY-091. In a syngeneic model of 4T1, we observed a significant reduction in tumor growth and synergistic tumor regression when combined with immune checkpoint blockade therapy. 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, CD8 T, Tregs and MDSCs in a lactate-rich culture condition mimicking lactate level in the TME. NGY-091 treatment strongly increased effector CD4 and CD8 T cells while significantly reducing suppressive function of Treg and MDSCs in vitro. These findings indicate the direct effect of NGY-091 on immune cell and validate the in vivo observations in 4T1 tumors. Therefore, NGY-091 intervenes two key hallmarks of cancer – metabolism and immunity and provides a novel avenue to therapeutically target aggressive breast cancer.
Citation Format: Sambad Sharma, Sanath Wijerathna, Kerui Wu, Abhishek Tyagi, Shih-Ying Wu, Kounosuke Watabe, Nelly Kuklin, Jaime Escobedo, Vincent Sandanayaka. Therapeutic efficacy of NGY-091 against triple negative breast cancer is mediated by direct cell killing and activation of antitumor immunity [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-07-21.