EDHSS206, an Exquisitely Selective Inhibitor of TAK1, Targets Pro Survival TNFFFDependent Signaling, Inducing Apoptosis in Rheumatoid Arthritis and Breast Cancer Models

Tumor necrosis factor alpha (TNFα) administration has shown limited therapeutic utility in cancer and inflammatory disorders due to dose‐limiting side effects. We propose an alternative approach to targeting TNFα‐mediated diseases by selectively inducing the TNFα apoptotic response in TNFα‐rich microenvironments. TAK1 acts as a key mediator between survival and cell death in TNFα signaling. We report a novel potent and exquisitely selective TAK1 inhibitor (EDHS‐206, IC50 9.5nM) that induces apoptosis in a TNFα‐dependent manner in models of metastatic breast cancer and rheumatoid arthritis. Co‐crystallization studies demonstrated that EDHS‐206 inhibits the kinase in a DFG‐in conformation. Kinetic analysis of EDHS‐206‐TAK1 interactions revealed a substrate‐like intermolecular autophosphorylation mechanism for TAK1 activation, during which EDHS‐206 delays the proceedings of the rate‐limiting step. EDHS‐206 represents an attractive starting point for the development of a novel generation of inhibitors that greatly sensitize cells to TNFα‐induced cell death, potentially broadening the therapeutic efficacy of TNFα.