TREM2 and cancer: Recently, Molgora and colleagues found that Trem2-/- mice are more cancer resistant and more responsive to anti-PD-1 immunotherapy than wild-type mice (57), and treatment with anti-TREM2 mAb combined with anti-PD-1 inhibited tumor growth and promoted tumor regression, with reduced MRC1+ and CX3CR1+ macrophages in the tumor infiltrate, but the expansion of myeloid subsets expresses immunostimulatory molecules that promote improved T-cell responses.