Radiation resistance remains a major barrier to effective chemoradiation therapy (CRT) in esophageal adenocarcinoma (EAC). Ferroptosis, a lipid peroxidation-driven cell death pathway, is increasingly recognized as a regulator of tumor\u2013immune interactions. We investigated how macrophage polarization and ferroptotic susceptibility shapes microenvironmental resistance to CRT in vitro, in vivo, and in EAC patient tumor tissues. scRNA-seq and Lunaphore COMET were performed on patient biopsies to characterize macrophage subsets and ferroptosis markers at single-cell resolution. In vitro ferroptosis assays were performed in THP-1, and human PBMC-derived M1\/M2 macrophages following 0\u201312 Gy radiation \u00b1 RSL3 or ferrostatin. Ferroptotic activity was assessed by CellTiter-Glo, BODIPY-C11 oxidation, and GPX4 staining (Confocal, flowcytometry). To interrogate ferroptosis in vivo, we generated myeloid-specific GPX4-deficient mice (B6.GPX4F\/F;Lyz2-Cre+\/+) and validated inducible GPX4 deletion following tamoxifen administration in alveolar and BM derived macrophages. scRNA-seq confirmed robust myeloid cell expansion in both GR and NR and revealed that pro-ferroptosis gene programs were upregulated in NR both at baseline and during CRT. Conversely, anti-ferroptosis pathways (GPX4) were enriched in GR and suppressed in NR.\u00a0 In vitro, radiation significantly potentiated RSL3-induced ferroptosis in bot h human and murine macrophage-like cells. M2 macrophages were sensitive to radiation-induced ferroptosis, while M1 macrophages were resistant. COMET profiling revealed that non-responders (NR) displayed higher baseline M2 macrophage density and significantly elevated ferroptosis marker 4-HNE in both M1 and M2 subsets. During CRT, NRs exhibited a further increase in M2 macrophage infiltration, reinforcing an immunosuppressive TME, whereas good responders (GR) maintained higher M1 representation. Macrophage polarization jointly governs CRT response. Non-responders are characterized by (i) M2-dominant macrophage landscapes, (ii) elevated lipid peroxidation, (iii) expansion of ferroptosis-primed myeloid subsets, and (iv) persistent activation of pro-ferroptosis pathways. Collectively, these findings nominate macrophage ferroptosis as a targetable axis for radio-sensitization in EAC.<\/p>\n","protected":false},"featured_media":5106,"template":"","meta":{"_acf_changed":false},"schedule":[5],"speaker-category":[6],"class_list":["post-5105","speaker","type-speaker","status-publish","has-post-thumbnail","hentry","schedule-day-1","speaker-category-speakers"],"acf":[],"yoast_head":"\n