Tumor-associated macrophage surface markers (TAM markers)

Tumor-associated macrophages (TAMs) are a major component of the leukocyte infiltrate in solid tumors and play a pivotal role in the tumor microenvironment (Mantovani et al., 2017, Nature Reviews Clinical Oncology). They generally adopt an M2-like polarized state, which facilitates tumor progression by promoting angiogenesis, suppressing adaptive immune responses, and supporting metastasis. Because of their pro-tumorigenic roles, TAMs and their specific surface biomarkers are significant targets for cancer immunotherapy. Drugs targeting these markers aim to deplete TAM populations, prevent their recruitment to the tumor site, or polarize them toward a tumor-killing M1-like phenotype (Pathria et al., 2019, Science). Common markers used in clinical and preclinical settings include CD163, CD206, and the Colony Stimulating Factor 1 Receptor (CSF1R). However, the high plasticity of macrophages and the overlap of markers with healthy tissue macrophages present significant therapeutic challenges.

Other names

TAM surface antigensM2 macrophage markersTumor-infiltrating macrophage markersTumor-associated macrophage biomarkers

Therapeutic strategies targeting TAM surface markers include the depletion of macrophage populations (e.g., via CSF1R inhibition), the blockade of macrophage recruitment to the tumor microenvironment (e.g., via CCL2-CCR2 axis inhibition), and the phenotypic reprogramming of pro-tumorigenic M2-like macrophages into anti-tumor M1-like macrophages (Cassetta & Pollard, 2018, Nature Reviews Drug Discovery; Pathria et al., 2019, Science).