Ferroptotic tumor cells revamp tumor-associated macrophage antigen presentation to unleash immune checkpoint blockade efficacy

Activation of antigen presentation has been shown to contribute to improved immunotherapy outcomes. Herein, we show that inducing tumor cell ferroptosis boosts anti-tumor immunity by potentiating major histocompatibility complex II (MHC-II)- dependent antigen presentation in tumor-infiltrating macrophages. Supporting our findings with multi-omics data, we reported that ferroptotic tumor-derived all-trans retinoic acid (ATRA) is a novel regulator of MHC-II in macrophages. ATRA directly targets CD38 through transcriptional factor RARα and activates master regulator TFEB to control MHC-II expression by inducing autophagy. Clinically, a ferroptosis signature is associated with better immunotherapy response. We also innovatively develop a drug-free nano-redox lever (DFNRL) to circumvent the non-specific limitations of conventional drugs, which specifically targets and disrupts glutathione metabolism in tumor cells by accepting electrons, thereby boosting ferroptosis-mediated immune stimulation. This synergizes with anti–PD-1 immunotherapy across preclinical models. Our study answers an unidentified role for ferroptosis in modulating anti-tumor immunity and provides a clinically translatable approach to enhance immunotherapy efficacy.