BTK and systemic lupus erythematosus: Next to mouse studies concerning Btk inhibition in autoimmune diseases, currently clinical trials are ongoing with several Btk inhibitors in autoimmune disease patients, including RA (CC-292, HM71224, M2951, and GS-4059) and SLE (BIIB068, MSC2364447C, and M2951) (www.clinicaltrials.gov).