• IRAK4 is an important mediator of inflammatory response, involved in the activation of the TLR and interleukin-1 receptor signal transduction pathways by binding to myeloid differentiation factor 88 (MyD88).• PF-06650833 reduced the levels of inflammatory markers in rodent models of systemic lupus erythematosus and rheumatoid arthritis in phase I clinical studies (94). Here, MYD88 is linked to rheumatoid arthritis.