Multiagent Intratumoral Immunotherapy Can Be Effective in A20 Lymphoma Clearance and Generation of Systemic T Cell Immunity

SIMPLE SUMMARY: Immunotherapy has shown promise clinically, but resistance to therapies remains an issue. Using novel combinations of immunotherapies may help overcome these barriers. Here, we tested combinations of immunotherapy agents that were administered intratumorally using a mouse model of lymphoma. We show that combination treatment with multiple immune-modulating agents allowed for greater tumor control and induced tumor-specific long-term immunological memory that was T cell dependent. Combination treated animals showed modest alterations in immune cell subsets in lymphoid tissues and had increased immune infiltration to tumors 24 h after treatment. Future studies should evaluate the impact of other immunotherapy combinations on a variety of tumor types. ABSTRACT: The use of immunotherapies has shown promise against selective human cancers. Identifying novel combinations of innate and adaptive immune cell-activating agents that can work synergistically to suppress tumor growth and provide additional protection against resistance or recurrence is critical. The A20 murine lymphoma model was used to evaluate the effect of various combination immunotherapies administered intratumorally. We show that single-modality treatment with Poly(I:C) or GM-CSF-secreting allogeneic cells only modestly controls tumor growth, whereas when given together there is an improved benefit, with 50% of animals clearing tumors and surviving long-term. Neither heat nor irradiation of GM-CSF-secreting cells enhanced the response over use of live cells. The use of a TIM-3 inhibitory antibody and an OX40 agonist in combination with Poly(I:C) allowed for improved tumor control, with 90% of animals clearing tumors with or without a combination of GM-CSF-secreting cells. Across all treatment groups, mice rejecting their primary A20 tumors were immune to subsequent challenge with A20, and this longstanding immunity was T-cell dependent. The results herein support the use of combinations of innate and adaptive immune activating agents for immunotherapy against lymphoma and should be investigated in other cancer types.