Although phase I trials have shown good tolerability of different BTK inhibitors (evobrutinib, spebrutinib, tirabrutinib and fenebrutinib) in people with RA, phase II trials evaluating evobrutinib, spebrutinib, fenebrutinib and acalabrutinib revealed that treatment efficacy was not as strong as expected on several outcome parameters [41, 42]. The gene discussed is BTK; the disease is rheumatoid arthritis.