A new study reported that TREM2 signaling can act as a switch to supercharge CAR macrophages against breast cancer, addressing the broader problem that macrophages can adopt tumor-promoting identities. By modulating TREM2, the researchers aimed to shift macrophage behavior toward a more tumoricidal state. In a separate mechanistic line, research highlighted how radiotherapy may backfire through PD-1-positive monocytes that contribute to treatment resistance. The findings suggest that immune cell phenotypes emerging after radiation can alter the effectiveness of subsequent therapy. Together, the updates reflect a continued emphasis on reshaping the tumor immune microenvironment—either by targeting specific receptors on innate cells or by anticipating immune drivers of resistance after standard modalities.