Abstract 6711: Investigating MyD88 and NLRP3 pathway modulation in a TLR4 and TLR9 driven immunotherapy in a murine model of ovarian cancer

Abstract Ovarian cancer remains one of the most devastating gynecologic malignancies, partly due to an immunosuppressive tumor microenvironment (TME) that limits immunotherapy efficacy. Our previous work showed that syngeneic cancer cell-based immune therapy containing monophosphoryl lipid A (TLR4 agonist) and CpG (TLR9 agonist) stimulates cancer-specific immune responses. Both receptors signal through MyD88 to activate NF-κB and pro-inflammatory cytokine production. These pathways also intersect with the NLRP3 inflammasome, which amplifies inflammation through IL-1β and IL-18. Controlled activation may enhance antitumor immunity, whereas dysregulated inflammasome signaling can promote chronic inflammation and immune suppression. Understanding how MyD88 and NLRP3 shape vaccine efficacy is therefore essential.This study evaluates how inhibition of MyD88 and NLRP3 affects the therapeutic efficacy of our ovarian cancer immune therapy. FVB mice bearing ovarian tumors received TLR-agonist silicified cancer cell immunotherapy with or without the NLRP3 inhibitor MCC950 (10 mg/kg) or the MyD88 inhibitor TJM-2010 (50 mg/kg). Inhibitors were administered around each immune-therapy dose. Ascitic immune cells were analyzed by spectral flow cytometry to assess immune subsets and activation markers.Blockade of the NLRP3 pathway accelerated ovarian cancer growth, while TLR-agonist immune therapy blocked tumor progression and cleared existing tumors. NLRP3 inhibition reduced therapeutic efficacy, tumor size decreased but complete clearance was not achieved. On Day 12, the immune-therapy group showed a significant reduction in tumor burden compared to PBS (p = 0.0034). The immune-therapy + NLRP3-inhibited group also differed from PBS but with diminished benefit (p = 0.0091). By Day 16, both BR5 immune-therapy and BR5 + inhibitor groups showed highly significant reductions in tumor burden compared to PBS (p 0.0001). These findings demonstrate that NLRP3 signaling contributes critically to TLR4/TLR9-mediated antitumor responses. Ongoing studies will clarify how MyD88 and NLRP3 coordinate innate immune activation and guide future combination strategies to enhance immunity and overcome suppression within the ovarian TME. AI Disclosure:ChatGPT was used to assist with editing and wording of this abstract. All scientific content, study design, and interpretation were generated and verified by the authors. Citation Format: Ania V. Klas, Rita E. Serda. Investigating MyD88 and NLRP3 pathway modulation in a TLR4 and TLR9 driven immunotherapy in a murine model of ovarian cancer abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 6711.