Abstract B055: Lipid nanoparticle delivery of IL-2 mRNA boosts survival and T cell response in a murine ovarian cancer model

Abstract Introduction: Ovarian cancer (OC) tumors commonly display an immune-cold tumor microenvironment (TME) characterized by a high presence of immunosuppressive cells and low level of anti-tumor immune cell infiltration. Studies show that higher levels of immune presence and activation in tumors correlate with better patient prognosis, though clinical trials using single-agent anti-PD1 have not had encouraging results. Therefore, there is a need to develop a tumor-targeting therapeutic that enhances anti-tumor immune infiltration and activation within tumors. Experiments: C57BL/6 mice were intraperitoneally injected (IP) with the murine OC model ID8TP53-/-;BRCA2-/-. For bioluminescence imaging (BLI) experiments, on day 45 post cancer injection, the mice received IP phosphate buffered solution (PBS) or encapsulating Luciferase mRNA (LNP-Luc). For immunoprofiling experiments, starting day 40, the mice received either IP IL-2 mRNA (LNP-IL-2), PBS, or LNP-Luc daily for 5 days. To profile, omental tumors were collected post treatment, dissociated, stained for selected immune markers, and analyzed either by conventional or spectral flow cytometry. Results: We identified 3 potential LNP candidates that preferentially target OC tumor cells. To test targeting specificity, we IP delivered encapsulated luciferase mRNA in the LNPs into tumor-bearing mice. Through BLI, we identified an LNP termed L46 as our ideal candidate as we observed luminescence in omental and mesenteric tumors with no luminescence in the liver, spleen, or kidneys - sites commonly found to accumulate LNPs and can cause toxicity. Using L46, we sought to test its ability to induce immune infiltration into typically immune-cold ovarian tumors. Encapsulating human IL-2 mRNA, we confirmed by enzyme-linked immunosorbent assay (ELISA) the presence of IL-2 protein in ascites only within the LNP-IL-2 treated mice compared to LNP-Luc and PBS controls. With this IL-2 mRNA delivery, flow cytometry showed significantly increased infiltration of CD45+ cells and CD3+ T cells compared to both controls. Additionally, CD8+ T cells were significantly more activated (higher %CD25+ and higher intensity of ICOS) and showed higher degranulation potential (higher %GZMB+), while total CD3+ T cells were significantly less exhausted (lower %PD1+). This treatment showed no observed toxicity and prolonged overall survival from an average of 8 weeks in the PBS and LNP-Luc groups to 13. 5 weeks in the LNP-IL-2 group. Conclusion: Our LNP L46 preferentially targets OC cells without being endocytosed in benign tissue, allowing for targeted therapeutic delivery and potential minimization of side effects. With this tumor-targeting ability, L46 delivery of IL-2 mRNA induced translation of IL-2 protein, prolonged mouse survival, increased immune cell presence, and significantly increased T cell infiltration and activation. These findings emphasize the therapeutic potential of tumor-targeted IL-2 mRNA delivery in enhancing anti-tumor immunity and prolonging survival in OC. Citation Format: Manon Miller, Jaidev Bapat, Kailea Wiese, Sofia Ruau, Wanda Gan, Leah Wormack, Rohit Sharma, Atip Lawanprasert, Niren Murthy, Alan Ashworth, Katherine Fuh. Lipid nanoparticle delivery of IL-2 mRNA boosts survival and T cell response in a murine ovarian cancer model abstract. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Ovarian Cancer Research; 2025 Sep 19-21; Denver, CO. Philadelphia (PA): AACR; Cancer Res 2025;85 (18Suppl): Abstract nr B055.