BTK and autoimmune hemolytic anemia: Based on the above evidence of the pathogenic roles for BTK in autoimmunity, 4 clinical trials are testing the efficacy of ibrutinib (2 trials) and acalabrutinib (2 trials) in autoimmune diseases, including autoimmune hemolytic anemia (AIHA) and rheumatoid arthritis (RA) (Tables 1 and 2).