Combined immune checkpoint protein blockade and low dose whole body irradiation as immunotherapy for myeloma

Weiqing Jing, Jill A. Gershan, James Weber, Dominique Tlomak, Laura McOlash, Catherine Sabatos-Peyton, Bryon D. Johnson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

97 Scopus citations

Abstract

Background: Multiple myeloma is characterized by the presence of transformed neoplastic plasma cells in the bone marrow and is generally considered to be an incurable disease. Successful treatments will likely require multi-faceted approaches incorporating conventional drug therapies, immunotherapy and other novel treatments. Our lab previously showed that a combination of transient lymphodepletion (sublethal whole body irradiation) and PD-1/PD-L1 blockade generated anti-myeloma T cell reactivity capable of eliminating established disease. We hypothesized that blocking a combination of checkpoint receptors in the context of low-dose, lymphodepleting whole body radiation would boost anti-tumor immunity.Methods: To test our central hypothesis, we utilized a 5T33 murine multiple myeloma model. Myeloma-bearing mice were treated with a low dose of whole body irradiation and combinations of blocking antibodies to PD-L1, LAG-3, TIM-3, CD48 (the ligand for 2B4) and CTLA4.Results: Temporal phenotypic analysis of bone marrow from myeloma-bearing mice demonstrated that elevated percentages of PD-1, 2B4, LAG-3 and TIM-3 proteins were expressed on T cells. When PD-L1 blockade was combined with blocking antibodies to LAG-3, TIM-3 or CTLA4, synergistic or additive increases in survival were observed (survival rates improved from ~30% to >80%). The increased survival rates correlated with increased frequencies of tumor-reactive CD8 and CD4 T cells. When stimulated in vitro with myeloma cells, CD8 T cells from treated mice produced elevated levels proinflammatory cytokines. Cytokines were spontaneously released from CD4 T cells isolated from mice treated with PD-L1 plus CTLA4 blocking antibodies.Conclusions: These data indicate that blocking PD-1/PD-L1 interactions in conjunction with other immune checkpoint proteins provides synergistic anti-tumor efficacy following lymphodepletive doses of whole body irradiation. This strategy is a promising combination strategy for myeloma and other hematologic malignancies.

Original languageEnglish (US)
Article number2
JournalJournal for immunotherapy of cancer
Volume3
Issue number1
DOIs
StatePublished - Jan 20 2015

Keywords

  • 2B4
  • Blockade
  • CTLA4
  • Immune checkpoint proteins
  • LAG-3
  • Low dose whole body irradiation
  • Myeloma
  • PD-L1
  • TIM-3

ASJC Scopus subject areas

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

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