(J-370) Local delivery of pyroptosis-triggered mRNA lipid nanoparticles enhances cancer immunotherapy in multiple immunologically cold tumor models

Introduction:
Synergistically eliciting T-cell immune responses with inflammatory cytokines or immune agonists in cancer immunotherapy is a promising strategy to relieve immunosuppressive cold tumor microenvironment (TME), yet current treatments often fail to induce a cascade of cancer-immunity cycle for effective antitumor immunity. Pyroptosis, an inflammatory type of cell death triggered by the pore-forming N-terminal domain of gasdermin (GSDM), has garnered increasing scientific evidence demonstrating its involvement in antitumor immunity by inducing immunogenic cell death (ICD) in tumor cells. Even though it is an encouraging discovery in cancer immunotherapy, cleavage in the N terminus is required to activate pyroptosis. Herein, we propose a newly single-agent pyroptosis-triggered mRNA lipid nanoparticles (LNPs) strategy, which induces a transformation of cold tumors into hot tumors and elicits the cancer-immunity cycle.
Materials and Methods:
The newly developed GSDMBNT mRNA@LNP formulation is self-assembled by an ionizable cationic lipid (AA3-Dlin), phospholipid (DOPE), cholesterol, and PEG, and GSDMBNT mRNA is encapsulated inside LNPs via electrostatic interactions. HEK 293, Hela, 4T1, and B16F10-Luc cells transfected with GSDMBNT mRNA@LNPs were used to examine the changes in cell morphology, cell death, and the expression of biomarkers associated with immunogenic cell death (ICD). In addition, we employed 4T1-bearing, B16F10-bearing, and B16F10 dual-tumor models to explore the antitumor efficacy and the underlying anti-tumor immune mechanisms mediated by the pyroptosis-triggered mRNA nanomedicine.
Results, Conclusions, and Discussions:
In this study, the pyroptosis-triggered mRNA nanomedicine can be successfully delivered into target tumor tissue, where the mRNA is translated into the N-terminus of the GSDMB protein, triggering pyroptosis directly without protease cleavage. Pyroptosis further triggers the expression of proinflammatory cytokines (TNF-α, IFN-γ, IL-1β, IL-18), induces ICD, and initiates the activation and recruitment of immune cells (dendritic cells, CD4+ T cells, CD8+ T cells, NK and NK T cells) within the tumor site. This cancer-immunity cycle creates a favorable immunogenic hot tumor microenvironment that synergies with immune checkpoint blockade (ICB)-mediated immunotherapy (such as anti-PD-1 antibody). We also observed that this enhanced antitumor immunity locally administered to one tumor stimulates a systemic antitumor response, contributing to cures in the poorly immunogenic tumor model and eliciting control over distant untreated lesions.
Overall, we demonstrated an approach to induce pyroptosis and promote anti-tumor immune responses in cold tumor models using mRNA lipid nanoparticles encoding the N-terminal domain of gasdermin B, including in combination with ICB.

References:
1 Li, F. et al. mRNA lipid nanoparticle-mediated pyroptosis sensitizes immunologically cold tumors to checkpoint immunotherapy. Nature Communications 14, 4223 (2023).