Itaconate enhances oncolytic virotherapy by multitarget inhibition of antiviral and inflammatory pathways

Altered metabolism and defective innate immune responses are hallmarks of tumor cells, creating a niche that can be exploited by viruses with oncolytic properties. However, heterogeneity in responses to oncolytic virotherapy is a barrier to clinical effectiveness. Resistance to oncolytic virotherapy exists and occurs via inhibition of viral spread within the tumor that may result in treatment failures. Here we show that the Krebs cycle-derived metabolite itaconate and its chemical derivatives or natural isomers enhance oncolytic virotherapy with VSVΔ51M in various models including resistant cancer cell lines, murine tumor biopsies, three-dimensional (3D) patient-derived colon tumoroids and organotypic brain tumor slices. The strongest sensitizing effect to VSVΔ51M infection within the itaconate family is elucidated by 4-octyl itaconate (4-OI), a known activator of nuclear factor erythroid 2-related factor 2 (NRF2). Importantly, the sensitization to VSVΔ51M with 4-OI is not observed in non-cancer primary human cells, healthy mouse-derived tissues, and normal human colon organoids. Additionally, 4-OI improves the virus spread within a resistant mouse colon tumor model in vivo. Mechanistically, we found that the effect of 4-OI is not mediated by NRF2 or KEAP1. Instead, we show that 4-OI targets multiple pathways including the RIG-MAVS, the IKKβ-NF-κB and the JAK1-STAT1 pathways through the modification of cysteine residues in MAVS, IKKβ and JAK1, respectively. Here, we propose that the combination of a metabolite-derived drug with an oncolytic virus agent can greatly improve anticancer therapeutic outcomes by direct interference with the type I IFN and NF-κB-mediated antiviral responses.