Abstract 3470: Intratumoral cytokine delivery combined with checkpoint blockade improves immunotherapy responses in immune-infiltrated oral cancers

Abstract Cytokine therapies improve antigen priming, increase effector immune cells in the tumor immune microenvironment (TIME), and enhance cytolytic activity. There is strong interest in the interleukin (IL) family to activate effector immune cells in the TIME. Interleukin-12 (IL-12) is known for its pro-inflammatory effects, T-cell differentiation properties, regulation of natural killer (NK) cell responses, and production of interferon-gamma (IFNγ). The TIME in head and neck squamous cell carcinoma (HNSCC) impairs tumor-infiltrating lymphocyte function, decreases the production of effector cytokines, and contains suppressive immunocytes. Immune checkpoint inhibitors (ICIs) have shown promise in several solid cancers with similar mutation burden and immune infiltration as HNSCC. However, most HNSCC patients do not respond to treatment with single-agent immunotherapy, in large part due to the immunosuppressive TIME. Therefore developing strategies to mitigate the suppressive tumor immune microenvironment and elicit a robust anti-tumor immune response through combinatorial treatments is key. Herein, we combined anti-programmed cell death protein-1 (α-PD-1) with IL-12 to reverse exhausted phenotypes and activate effector immune cells in the HNSCC TIME. We hypothesize that the combination of IL-12 and α-PD-1 therapy will stimulate anti-tumor effector immunocytes to target immune-infiltrated and immune-excluded TIME in the preclinical oral cancer models, MOC1 and MOC2. Continuous treatments of intratumoral IL-12 and systemic α-PD-1 either as monotherapies or in combination were administered to MOC1 tumor-burdened mice. We observed tumor regression in the MOC1 tumor-burdened mice with IL-12 + α-PD-1 combinatorial treatments, IL-12, and α-PD-1 monotherapies. Mice that rejected the primary tumor challenge were rechallenged with MOC1 cells. We observed complete responses in IL-12 + α-PD-1 treatment groups and tumor regression in IL-12 monotherapy groups. Additionally, in the more aggressive HNSCC preclinical model, MOC2, IL-12 treatments led to prolonged survival. Overall, our results demonstrate the effectiveness of IL-12 + α-PD-1 combinatorial treatments in an immune-infiltrated HNSCC preclinical model. Future studies will include the addition of small molecules, such as Stimulator of Interferon Genes (STING) agonists, to enhance antigen presentation and activate anti-tumor effector cells to combat an aggressive TIME. Citation Format: Andrea H. Molina, Gemalene M. Sunga, Neeraja Dharmaraj, Nourhan I. Hussein, Andrew G. Sikora, Simon Young. Intratumoral cytokine delivery combined with checkpoint blockade improves immunotherapy responses in immune-infiltrated oral cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3470.