Perouzel, E. | Search bioRxiv

bioRxiv2023

The defined TLR3 agonist, Nexavant, exhibits anti-cancer efficacy and potentiates anti-PD-1 antibody therapy by enhancing immune cell infiltration.

Nexavant has been reported as an alternative to the TLR3 agonist of Poly(I:C) and its derivatives. The physicochemical properties, signaling pathways, anti-cancer effects, and mechanisms of Nexavant were investigated. Nexavants distinct nature, compared to Poly(I:C), was evident through precise quantification, thermostability, and resistance to RNase A. Unlike Poly (I: C) which activates TLR3, RIG-I and MDA5, Nexavant stimulates the signaling through TLR3 and RIG-I but not MDA5. Intratumoral Nexavant treatment led to a unique immune response compared to Poly(I:C), immune cell infiltration, and suppression of tumor growth in various animal cancer models. Nexavant therapy outperformed anti-PD-1 antibody treatment in all tested models and showed a synergistic effect in combinational therapy, especially in well-defined cold tumor models. The effect was similar to Nivolumab in a humanized mouse model. Intranasal instillation of Nexavant recruited immune cells (NK, CD4+ T, CD8+ T) to the lungs, suppressing lung metastasis and improving animal survival. Our study highlighted Nexavants defined nature for clinical use, unique signaling pathways, and its potential as a standalone anti-cancer agent or in combination with anti-PD-1 antibody. Simple SummaryNexavant, a newly reported TLR3 agonist, has advantages over Poly(I:C) in quality control and pre-clinical efficacy. Here, we further investigated Nexavants physicochemical properties, downstream signaling pathways, anti-cancer efficacy, and mechanism of action. Nexavant was homogenous in solution, less sensitive to RNase A, and showed thermostability compared with Poly(I:C). Unlike Poly(I:C), the TLR3, RIGI, and MDA5 activator, Nexavant only activated TLR3 and RIG-I but not MDA5. Administration of Nexavant either by intratumoral or intranasal route suppressed tumor growth in various cancer models. Combination therapy with anti-PD-1 antibody exhibited synergistic tumor growth inhibition than the respective monotherapies. This study demonstrated that Nexavant could be more suitable for clinical use over Poly(I:C) and applied as an anti-cancer agent in the presence or absence of an anti-PD-1 antibody.

immunology↗

bioRxiv2023

STING activation counters glioblastoma by vascular alteration and immune surveillance

Glioblastoma (GBM) is an aggressive brain tumor with a median survival of 15 months and has limited treatment options. Immunotherapy with checkpoint inhibitors has shown minimal efficacy in combating GBM, and large clinical trials have failed. New immunotherapy approaches and a deeper understanding of immune surveillance of GBM are needed to advance treatment options for this devastating disease. In this study, we used two preclinical models of GBM: orthotopically delivering either GBM stem cells or employing CRISPR-mediated tumorigenesis by adeno-associated virus, to establish immunologically proficient and non-inflamed tumors, respectively. After tumor development, the innate immune system was activated through long-term STING activation by a pharmacological agonist, which reduced tumor progression and prolonged survival. Recruitment and activation of cytotoxic T-cells were detected in the tumors, and T-cell specificity towards the cancer cells was observed. Interestingly, prolonged STING activation altered the tumor vasculature, inducing hypoxia and activation of VEGFR, as measured by a kinome array and VEGF expression. Combination treatment with anti-PD1 did not provide a synergistic effect, indicating that STING activation alone is sufficient to activate immune surveillance and hinder tumor development through vascular disruption. These results guide future studies to refine innate immune activation as a treatment approach for GBM, in combination with anti-VEGF to impede tumor progression and induce an immunological response against the tumor.

cancer biology↗