IRAK4 / BTK

Class

Small molecule dual kinase inhibitor (first-in-class dual IRAK4/BTK inhibitor)

Pathway

Toll-like receptor/IL-1R signaling (IRAK4) and B-cell receptor signaling (BTK)

IRAK4 and BTK are intracellular signaling enzymes that sit at the convergence of two distinct arms of the immune system, and a single molecule capable of inhibiting both aims to interrupt inflammatory and immune-cell proliferative signals from two directions at once. IRAK4 (interleukin-1 receptor-associated kinase 4) acts immediately downstream of Toll-like receptors and interleukin-1 family receptors, transmitting signals that trigger production of inflammatory cytokines as part of the innate immune response. BTK (Bruton's tyrosine kinase) operates downstream of the B-cell receptor, and is essential for the survival, proliferation, and antibody production of B lymphocytes, while also contributing to signaling in other immune cell types. Both pathways ultimately activate the transcription factor NF-κB, which drives expression of inflammatory and pro-survival genes. In several diseases, notably certain B-cell lymphomas carrying activating mutations in the adaptor protein MyD88, and autoimmune conditions such as lupus, both innate (IRAK4) and adaptive (BTK) signaling contribute independently to disease persistence. A dual inhibitor is designed to address this coupled biology within a single agent, rather than relying on two separate drugs, on the rationale that blocking only one arm may leave disease processes able to persist through the other.