PRDX6 Modulates Immune Checkpoint Inhibitor Response by Antagonizing Ferroptosis Induced By HDAC Inhibitors

Therapeutic resistance limits the efficacy of histone deacetylase (HDAC) inhibitors and immune checkpoint therapies in cancer. While HDAC inhibitors can induce ferroptosis, tumor cells often evade this cell death via antioxidant defenses. Here we identify peroxiredoxin 6 (PRDX6) as a critical modulator of resistance to HDAC inhibitor largazole by suppressing ferroptosis through its phospholipase A2 activity and maintaining GPX4 expression. Using genome-wide CRISPR activation screening, biochemical assays, and syngeneic tumor models, we show that PRDX6 depletion enhances largazole-induced lipid peroxidation, ferroptotic stress, and reshapes the tumor microenvironment to promote T-cell infiltration and inflammatory cytokine release. Importantly, combining PRDX6 knockdown with HDAC inhibition potentiates anti-PD-L1 immunotherapy efficacy and prolongs survival in vivo. These findings reveal PRDX6 as a redox gatekeeper linking ferroptosis resistance to immune evasion and suggest that co-targeting PRDX6 and HDAC pathways may improve responses to cancer immunotherapy.