Monocytes in tumor: from the sight of Single-cell analysis

Abstract

Mononuclear phagocytes infiltration in the tumor microenvironment orchestra the tumor progression and are generally considered to impede the clinical effects of immune checkpoint blockade therapies. To overcome the traditional biased definition of monocytes, we reviewed some recent advances on the functions of monocytes and macrophages in tumor microenvironment based on single-cell analysis. We also summarized different subpopulations of monocytes and macrophages involved in immunotherapies and their potential applications in clinical study. In this script, we briefly introduce the developmental trajectory of mononuclear phagocytes, including monocytes, tumor associated macrophages (TAMs), DCs, myeloid-derived suppressive cells (MDSC) and their multiple functions in TME. We demonstrate the potential of monocytes and its derived cells being diagnostic and therapeutic targets, especially highlight the interaction between monocytes and immune checkpoint therapies.