Discovery of a Selective, Covalent IRAK1 Inhibitor with Antiproliferative Activity in MYD88 Mutated B-Cell Lymphoma.

Interleukin 1 (IL-1) receptor-associated kinases (IRAKs) are serine/threonine kinases that play critical roles in initiating the innate immune response against foreign pathogens. Additionally, dysregulation of IRAK1 signaling plays a role in neoplastic disorders. For example, IRAK1 was shown to be important for survival and proliferation in many B-cell lymphomas, including Waldenström's macroglobulinemia (WM) and ABC subtype Diffused Large B-cell Lymphoma (DLBCL) cells. Here, we report the discovery of a highly potent and selective covalent inhibitor of IRAK1, JH-X-119-01. Intact protein MS labeling studies confirmed that JH-X-119-01 irreversibly labels IRAK1 at C302. This compound exhibited cytotoxic activity at single digit micromolar concentrations in a panel of WM, DLBCL, and lymphoma cell lines expressing MYD88. Cotreatment of JH-X-119-01 with the BTK inhibitor ibrutinib resulted in synergistic killing effects in these systems. Taken together, JH-X-119-01 represents a highly selective probe of IRAK1 for further development.