Targeting resistance to radiation-immunotherapy in cold HNSCCs by modulating the Treg-dendritic cell axis

Michael W. Knitz, Thomas E. Bickett, Laurel B. Darragh, Ayman J. Oweida, Shilpa Bhatia, Benjamin Van Court, Shiv Bhuvane, Miles Piper, Jacob Gadwa, Adam C. Mueller, Diemmy Nguyen, Varuna Nangia, Douglas G. Osborne, Xiyuan Bai, Sarah E. Ferrara, Mary Keara Boss, Andrew Goodspeed, Matthew A. Burchill, Beth A.Jirón Tamburini, Edward D. ChanCurtis R. Pickering, Eric T. Clambey, Sana D. Karam

Research output: Contribution to journalArticlepeer-review


Background Numerous trials combining radiation therapy (RT) and immunotherapy in head and neck squamous cell carcinoma (HNSCC) are failing. Using preclinical immune cold models of HNSCC resistant to RT-immune checkpoint inhibitors, we investigate therapeutic approaches of overcoming such resistance by examining the differential microenvironmental response to RT. Methods We subjected two HPV-negative orthotopic mouse models of HNSCC to combination RT, regulatory T cells (Treg) depletion, and/or CD137 agonism. Tumor growth was measured and intratumorous and lymph node immune populations were compared among treatment groups. Human gene sets, genetically engineered mouse models DEREG and BATF3-/-, flow and time-of-flight cytometry, RNA-Seq, Treg adoptive transfer studies, and in vitro experiments were used to further evaluate the role of dendritic cells (DCs) and Tregs in these treatments. Results In MOC2 orthotopic tumors, we find no therapeutic benefit to targeting classically defined immunosuppressive myeloids, which increase with RT. In these radioresistant tumors, supplementing combination RT and Treg depletion with anti-CD137 agonism stimulates CD103 + DC activation in tumor-draining lymph nodes as characterized by increases in CD80 + and CCR7 + DCs, resulting in a CD8 T cell-dependent response. Simultaneously, Tregs are reprogrammed to an effector phenotype demonstrated by increases in interferon 3 +, tumor necrosis factorα +, PI3K +, pAKT + and Eomes + populations as well as decreases in CTLA4 + and NRP-1 + populations. Tumor eradication is observed when RT is increased to an 8 Gy x 5 hypofractionated regimen and combined with anti-CD25+ anti-CD137 treatment. In a human gene set from oral squamous cell carcinoma tumors, high Treg number is associated with earlier recurrence. Conclusions Regulating Treg functionality and DC activation status within the lymph node is critical for generating a T cell effector response in these highly radioresistant tumors. These findings underscore the plasticity of Tregs and represent a new therapeutic opportunity for reprogramming the tumor microenvironment in HNSCCs resistant to conventional radioimmunotherapy approaches.

Original languageEnglish (US)
Article numbere001955
JournalJournal for immunotherapy of cancer
Issue number4
StatePublished - Apr 21 2021


  • costimulatory and inhibitory t-cell receptors
  • dendritic cells
  • head and neck neoplasms
  • radioimmunotherapy
  • t-lymphocytes

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Molecular Medicine
  • Oncology
  • Pharmacology
  • Cancer Research


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