Abstract PO043: Layer-by-layer nanoparticles for non-toxic delivery of interleukin 12 to disseminated syngeneic ovarian tumors

Abstract

Abstract Ovarian cancer presents a notable challenge for cancer immunotherapy with less than a 10% objective response rate to checkpoint inhibitors (CPI). One strategy to augment the impact of checkpoint therapy is to initiate the infiltration of leukocytes into the tumor prior to CPI using pro-inflammatory cytokines. One particularly potent and promising cytokine is interleukin-12 (IL-12) – the hallmark Th-1 cytokine known to drive an influx of antigen presenting cells, expansion of cytotoxic T-cells, and NK-cell activation in a variety of solid tumors. Unfortunately, IL-12 has been hampered clinically by toxicity issues when administered systemically – a necessity for disseminated tumors such as advanced ovarian cancer. We have previously shown that nanoparticles engineered for cytokine delivery target human ovarian tumors in mouse models and that delivery of IL-12 using those particles enables the non-toxic delivery of IL-12 when given intratumorally to syngeneic tumors. In this study we demonstrate that these particles given systemically continue to limit IL-12 toxicity, accumulate within syngeneic, orthotopic models of ovarian tumors, induce tumor regressions, and reshape the immune microenvironment within those tumors. IL-12 was loaded onto the surface of negatively charged liposomes using the Ni-His interaction. The layer-by-layer process was then used to add layers of poly-L-arginine and poly-L-glutamine producing a final diameter of 120 nm and zeta potential of -60 mV. These layered nanoparticles (LNPs) preferentially accumulated in intraperitoneal HM-1 ovarian tumor nodules when given intravenously and intraperitoneally with a 30% increase in concentration over unlayered nanoparticles (ULNPs) as measured via fluorescence. IL-12 accumulation measured using ELISA was shown to correlate with NP accumulation for LNPs but not ULNPs. LNPs were non-toxic (via weight loss) at doses deemed toxic with ULNPs or free IL-12. Intraperitoneal treatment with LNPs extended survival and caused tumor regression in 30% of mice at a dose deemed toxic for free IL-12 or ULNPs (10 µg IL-12 given once daily for 5 days). Flow cytometry revealed a marked increase in memory T-cells and a decrease in granulocytes. The LNPs also induced substantial upregulation of exhaustion markers in the infiltrating T-cells – especially the TIM3+TIGIT+PD1+ highly exhausted phenotype suggesting potential for future combination therapies. Citation Format: Sean G. Smith, Antonio E. Barberio, Ivan S. Pires, Mariane Melo, Darrell J. Irvine, Paula T. Hammond. Layer-by-layer nanoparticles for non-toxic delivery of interleukin 12 to disseminated syngeneic ovarian tumors [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO043.