Tumor-associated macrophage M2 (M2-TAM)

Tumor-associated macrophage M2 (TAM M2) refers to an alternatively activated phenotype of macrophages that reside within the tumor microenvironment (TME) and actively facilitate cancer progression [1, 13]. Unlike the pro-inflammatory M1 phenotype, M2-like TAMs exhibit immunosuppressive, pro-angiogenic, and tissue-remodeling functions that allow tumors to grow and evade host immunosurveillance [4, 7, 9]. These cells secrete high levels of anti-inflammatory cytokines like IL-10 and TGF-β, along with factors such as VEGF that promote the development of a tumor-supportive vascular network [5, 13]. M2 TAMs also facilitate invasion and metastasis by degrading the extracellular matrix via the secretion of various matrix metalloproteinases (MMPs) [13, 16]. Note that while this entry is identified as a target, it represents a heterogeneous cellular population or phenotype rather than a single molecular target; however, it is frequently targeted in clinical research via specific surface receptors such as CSF1R, CD206, and CD163 [1, 5, 12]. Therapeutic strategies currently focus on depleting these cells, blocking their recruitment to the tumor site, or reprogramming them into a tumor-killing M1 state [3, 9, 13, 15].

Other names

M2-like tumor-associated macrophageAlternatively activated macrophagePro-tumor macrophageTAM-M2M2-polarized macrophage

Targeting of M2 tumor-associated macrophages (TAMs) is primarily achieved through three strategies: selective depletion of the M2 population, often via inhibition of the Colony Stimulating Factor 1 Receptor (CSF1R) [5, 9, 13]; inhibition of monocyte recruitment from the circulation to the tumor site, typically by blocking the CCL2/CCR2 signaling axis [5, 9]; and the phenotypic reprogramming of immunosuppressive M2 macrophages into pro-inflammatory, anti-tumor M1 macrophages using agents such as PI3Kγ inhibitors, TLR agonists, or CD40 agonists [8, 11, 13].