Combination of radiotherapy and vaccination overcome checkpoint blockade resistance

Wenxin Zheng, Kinga B. Skowron, Jukes P. Namm, Byron Burnette, Christian Fernandez, Ainhoa Arina, Hua Liang, Michael T. Spiotto, Mitchell C. Posner, Yang Xin Fu, Ralph R. Weichselbaum

Research output: Contribution to journalArticle

39 Scopus citations

Abstract

The majority of cancer patients respond poorly to either vaccine or checkpoint blockade, and even to the combination of both. They are often resistant to high doses of radiation therapy as well. We examined prognostic markers of immune cell infiltration in pancreatic cancer. Patients with low CD8+ T cell infiltration and high PD-L1 expression (CD8+ TloPD-L1hi) experienced poor outcomes. We developed a mouse tumor fragment model with a trackable model antigen (SIYRYYGL or SIY) to mimic CD8+ TloPD-L1hi cancers. Tumors arising from fragments contained few T cells, even after vaccination. Fragment tumors responded poorly to PD-L1 blockade, SIY vaccination or radiation individually. By contrast, local ionizing radiation coupled with vaccination increased CD8+ T cell infiltration that was associated with upregulation of CXCL10 and CCL5 chemokines in the tumor, but demonstrated modest inhibition of tumor growth. The addition of an anti-PD-L1 antibody enhanced the effector function of tumor-infiltrating T cells, leading to significantly improved tumor regression and increased survival compared to vaccination and radiation. These results indicate that sequential combination of radiation, vaccination and checkpoint blockade converts non-T cell-inflamed cancers to T cell-inflamed cancers, and mediates regression of established pancreatic tumors with an initial CD8+ TloPD-L1hi phenotype. This study has opened a new strategy for shifting "cold" to hot tumors that will respond to immunotherapy.

Original languageEnglish (US)
Pages (from-to)43039-43051
Number of pages13
JournalOncotarget
Volume7
Issue number28
DOIs
StatePublished - Jan 1 2016

Keywords

  • Checkpoint blockade
  • Radiation therapy
  • T cell infiltration
  • Tumor model
  • Vaccination

ASJC Scopus subject areas

  • Oncology

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    Zheng, W., Skowron, K. B., Namm, J. P., Burnette, B., Fernandez, C., Arina, A., Liang, H., Spiotto, M. T., Posner, M. C., Fu, Y. X., & Weichselbaum, R. R. (2016). Combination of radiotherapy and vaccination overcome checkpoint blockade resistance. Oncotarget, 7(28), 43039-43051. https://doi.org/10.18632/oncotarget.9915