GPC3 and neoplasm: We find that Trem2 deficiency synergizes with GPC3-CAR-T to enhance tumor control by expanding endogenous tumor-specific CD8<sup>+</sup> T cells (not CAR-T amplification) and reeducating TAMs to an anti-tumor CXCL9<sup>hi</sup>/SPP1<sup>lo</sup> phenotype via metabolic reprogramming.