EZH2 inhibition activates dsRNA-interferon axis stress and promotes response to PD-1 checkpoint blockade in NSCLC

Lung cancer is the leading cause of cancer death and immunotherapy had been approved be a useful approach for NSCLC therapy. However, only part of the patients responds to checkpoint inhibitors. The EZH2, as a histone modification regulator, is overexpressed in NSCLC and negatively regulates the interferon-stimulated genes. Here, we demonstrate that EZH2 inhibition increases the double-strand RNA (dsRNA) level and then triggers the IFN pathway stress which is dependent on the pattern recognition receptors (TLR3, MDA5). The antigen presentation genes and PDL1 were also upregulated by inhibition of EZH2. Furthermore, in the immunocompetent LLC tumor model, the inhibition of EZH2 causes tumor regression and enhances the CD8(+)T cell infiltration. The EZH2 depletion triggers significant responses of the LLC mouse model to anti-PD1 therapy. This study identifies that inhibition of EZH2 promotes the dsRNA interferon driven antitumor immunity and enhances the anti-PD1 antitumor efficacy in NSCLC. These data suggest that EZH2 inhibition combined with anti-PD1/PDL1 is a promising lung cancer treatment strategy.