Researchers reported preclinical results for syncytial CAR macrophages that fuse CAR-engineered macrophages with neutrophils to increase tumor penetration and immune activity. Published in Nature Immunology, the “S-CAR-Ms” design integrates CAR-engineered macrophages with neutrophils to create a hybrid cell for cancer immunotherapy. In mouse models, the fused cells showed enhanced ability to penetrate tumors and extend antitumor effects compared with conventional approaches described in the study. The work positions macrophage-based CAR strategies as more flexible “living drug” platforms that can incorporate features of innate immune cells. The study adds to a shift toward engineering innate immune cells for solid tumors, where immune exclusion, insufficient infiltration, and suppressive microenvironments frequently limit responses. While still early-stage, the design indicates an engineering path for overcoming penetration barriers without relying solely on T-cell trafficking.