Nanoparticle Delivery of RIG-I Agonist Enables Effective and Safe Adjuvant Therapy in Pancreatic Cancer

Abstract

Local immunomodulation can be a promising strategy to augment the efficacy and decrease off-target toxicities associated with cancer treatment. Pancreatic cancer is resistant to immunotherapies due to the immunosuppressive tumor microenvironment. Herein, we investigated a therapeutic approach involving delivery of a short interfering double-stranded RNA (dsRNA), specific to Bcl2, with 5 0 triphosphate ends, by lipid calcium phosphate nanoparticles, in an orthotopic allograft KPC model of pancreatic cancer. Retinoic acid-inducible gene I (RIG-I)-like receptors can bind to 5 0 triphosphate dsRNA (ppp dsRNA), a pathogen-associated molecular pattern, producing type I interferon, while Bcl2 silencing can drive apoptosis of cancer cells. Our approach demonstrated a robust enrichment of tumor tissue with therapeutic nanoparticles and enabled a significant tumor growth inhibition, prolonging median overall survival. Nanoparticles encapsulating dual-therapeutic ppp dsRNA allowed strong induction in levels of pro-inflammatory Th1 cytokines, further increasing proportions of CD8 + T cells over regulatory T cells, M1 over M2 macrophages, and decreased levels of immunosuppressive B regulatory and plasma cells in the tumor microenvironment. Thus, these results provide a new immunotherapy approach for pancreatic cancer.

Tumor neoantigen heterogeneity impacts bystander immune inhibition of pancreatic cancer growth

“…We selected candidate binders based on %Rank rather than nM Affinity, following the recommendation of the server developers. We generated a cell line from the genetically engineered KPC mice model [19][20][21] with KRAS G12D and p53 R172H oncogenic driver mutations, and inoculated cells orthotopically in mice sharing the same genetic background, for two reasons: Firstly, having a non-spontaneous model allowed us to precisely control the frequency of neoantigen to assay the subsequent effect on tumor elimination while reasonably replicating the desmoplastic and immunosuppressive characters of the GEMM tumors. Secondly, it allowed us to engineer the cell line to express luciferase and quantitatively monitor tumor growth by bioluminescence imaging.…”

“…CRL-2539™), CT26-FL342 , and KPC19 cell lines in vitro using Lipofectamine 2000. Transfection Reagent manufacturer's instructions were followed for transfection.…”

Targeted Nanoparticle Delivery of Bifunctional RIG-I Agonists to Pancreatic Cancer

“…In this issue of Molecular Therapy, Das et al 1 harness surface-receptor targeting nanoparticle delivery to combat pancreatic ductal adenocarcinoma with bifunctional short interfering RNA (siRNA), which activates the innate immune receptor retinoic acidinducible gene I (RIG-I) and silences the anti-apoptotic protein Bcl-2. Nucleic acid receptor agonists are gaining importance in cancer therapy 2 as combination therapies employing checkpoint inhibitors open up new opportunities in immunotherapy and add momentum to the field.…”

“…A key challenge for nucleic acid therapeutics, however, is delivery, as they cannot freely traverse cell membranes and need to be formulated in ways that enable them to reach intracellular compartments. Das et al 1 add a further layer to this approach and use surface-modified nanoparticles to deliver RIG-I agonists to specific cancer cells in vivo.…”

“…Sigma receptors are highly expressed on many tumors 12 and, although their natu-ral ligands and function are incompletely understood, the Sigma1-receptor ligand anisamide is frequently used as a nanoparticle surface modification to enable tumor targeting in vivo. 13 In an orthotopic allograft mouse model of PDAC, Das et al 1 show that two low doses (5 mg per mouse and injection) of nanoparticles encapsulating a RIG-I-activating Bcl-2 siRNA are sufficient to induce tumor regression. They demonstrate a reduction of immunosuppressive M2 macrophages in tumor tissue as well as cytotoxic CD8 T cell infiltration and a proinflammatory tumor microenvironment, characterized by a reduction of interleukin 10 (IL-10)-expressing cells and increased numbers of interferon-g positive cells.…”