Combination therapy with NHS-muIL12 and avelumab (anti-PD-L1) enhances antitumor efficacy in preclinical cancer models

Purpose: To determine if combination therapy with NHS-muIL12 and the anti-PD-L1 antibody avelumab can enhance anti-tumor efficacy in preclinical models relative to monotherapies.<br /><br />Experimental Design: BALB/c mice bearing orthotopic EMT-6 mammary tumors and μMt^- mice bearing subcutaneous MC38 tumors were treated with NHS-muIL12, avelumab, or combination therapy; tumor growth and survival were assessed. Tumor recurrence following remission and rechallenge was evaluated in EMT-6 tumor-bearing mice. Immune cell populations within spleen and tumors were evaluated by FACS and immunohistochemistry. Immune gene expression in tumor tissue was profiled by Nanostring assay and plasma cytokine levels were determined by multiplex cytokine assay. The frequency of tumor antigen-reactive IFN--producing CD8⁺ T cells was evaluated by ELISpot assay. <br /><br />Results: NHS-muIL12 and avelumab combination therapy enhanced antitumor efficacy relative to either monotherapy in both tumor models. Most EMT-6 tumor-bearing mice treated with combination therapy had complete tumor regression. Combination therapy also induced the generation of tumor-specific immune memory, as demonstrated by protection against tumor rechallenge and induction of effector and memory T cells. Combination therapy enhanced cytotoxic NK and CD8⁺ T cell proliferation and T-bet expression, whereas NHS-muIL12 monotherapy induced CD8⁺ T cell infiltration into the tumor. Combination therapy also enhanced plasma cytokine levels and stimulated expression of a greater number of innate and adaptive immune genes compared with either monotherapy.<br /><br />Conclusions: These data indicate that combination therapy with NHS-muIL12 and ave­lumab increased antitumor efficacy in preclinical models, and suggest that combining NHS-IL12 and avelumab may be a promising approach to treating patients with solid tumors.

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