As a component of the tumor immune microenvironment, MDSCs and their related factors and functions, such as reactive oxygen species (ROS), indoleamine 2,3-dioxygenase (IDO), arginase 1 (ARG1), adenosine, and negative immune checkpoints, can remodel the suppressive immune microenvironment of tumors [10]. Here, ARG1 is linked to neoplasm.