AVA-ADR-001- a small molecular inhibitor of ADAR1 (Immuno-oncology target)

To inhibitors for ADAR1 and a strong rationale for the development of ADAR1 p150 inhibitors for cancer immunotherapy Here, we describe AVA-ADR-001, a potential first-in-class small molecule inhibitor of ADAR1 p150 targeting the Z alpha domain. AVA-ADR-001 binds specifically to the Z alpha domain of ADAR1 p150 as confirmed by fluorescence spectroscopy and showed significant interferon induction in THP1 macrophages, which have high ADAR1 p150 expression compared with monocytes. Proteomics and transcriptomics analysis revealed significant upregulation of interferon signaling upon treatment with AVA-ADR -001. Interestingly, activation of interferon signaling resulted in AVA-ADR-001 induced cell killing in ADAR1-independent cell lines. In addition, treatment with AVA-ADR -001 resulted in significant activation of PKR, which may explain the decreased cell proliferation. Finally, AVA-ADR-001 showed superior anti-tumor efficacy compared to anti-PD1 in an in vivo tumor efficacy study and has a moderately synergistic effect when combined. Overall, this study reveals that ADAR1 p150 inhibition by AVA-ADR-001 exerts a multipronged impact on anti-tumor efficacy mediated by immune cells, accumulation of interferons and activation of PKR, resulting in protein translation inhibition and cell proliferation arrest. Overall design: Comparative gene expression profiling analysis of RNA-seq data for A549 and HCT116 cells treated with AVA-ADR-001 for 24 h.