IRAK4 and rheumatoid arthritis: Pfizer compound PF-06650833 is the first compound to complete Phase I clinical trials as an IRAK4 inhibitor (ClinicalTrials.gov Identifiers: NCT02485769, NCT02224651 and NCT02609139) and it is currently in clinical Phase II trials for rheumatoid arthritis (RA) (ClinicalTrials.gov Identifier: NCT02996500).