Radiotherapy and Immunotherapy Promote Tumoral Lipid Oxidation and Ferroptosis via Synergistic Repression of SLC7A11

Cancer Discov. 2019 Dec;9(12):1673-1685. doi: 10.1158/2159-8290.CD-19-0338. Epub 2019 Sep 25.


A challenge in oncology is to rationally and effectively integrate immunotherapy with traditional modalities, including radiotherapy. Here, we demonstrate that radiotherapy induces tumor-cell ferroptosis. Ferroptosis agonists augment and ferroptosis antagonists limit radiotherapy efficacy in tumor models. Immunotherapy sensitizes tumors to radiotherapy by promoting tumor-cell ferroptosis. Mechanistically, IFNγ derived from immunotherapy-activated CD8+ T cells and radiotherapy-activated ATM independently, yet synergistically, suppresses SLC7A11, a unit of the glutamate-cystine antiporter xc-, resulting in reduced cystine uptake, enhanced tumor lipid oxidation and ferroptosis, and improved tumor control. Thus, ferroptosis is an unappreciated mechanism and focus for the development of effective combinatorial cancer therapy. SIGNIFICANCE: This article describes ferroptosis as a previously unappreciated mechanism of action for radiotherapy. Further, it shows that ferroptosis is a novel point of synergy between immunotherapy and radiotherapy. Finally, it nominates SLC7A11, a critical regulator of ferroptosis, as a mechanistic determinant of synergy between radiotherapy and immunotherapy.This article is highlighted in the In This Issue feature, p. 1631.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Transport System y+ / genetics*
  • Animals
  • Antineoplastic Agents, Immunological / administration & dosage*
  • Antineoplastic Agents, Immunological / pharmacology
  • CD8-Positive T-Lymphocytes / immunology
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Cell Survival / radiation effects
  • Down-Regulation
  • Ferroptosis / drug effects
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Immunotherapy / methods
  • Interferon-gamma
  • Lipid Metabolism / drug effects
  • Lipid Metabolism / radiation effects
  • Melanoma, Experimental / genetics
  • Melanoma, Experimental / therapy*
  • Mice
  • Oxidation-Reduction
  • Sulfasalazine / administration & dosage*
  • Sulfasalazine / pharmacology
  • Xenograft Model Antitumor Assays


  • Amino Acid Transport System y+
  • Antineoplastic Agents, Immunological
  • IFNG protein, human
  • SLC7A11 protein, human
  • Sulfasalazine
  • Interferon-gamma