Inhibition of murine myeloid suppressor cells increases CD8+ T cell activation in vitro

AACR 2023 -- Tumor microenvironment (TME) is rich in cells that potentially inhibit T cell function, such as regulatory T cells (Tregs) and myeloid derived suppressor cells (MDSCs). The purpose of this study was to develop an in vitro assay system to assess the ability of novel drugs to overcome MDSC-mediated immune suppression by monitoring changes to T cell function. Arginase 1 (ARG1), an enzyme that catalyzes L-arginine into L-ornithine and urea, is highly expressed in MDSCs. An ARG1 target, currently in clinical trials (INCB001158, CB-1158 from Calithera Biosciences), was used as a target of interest in this study.