JAK1 and rheumatoid arthritis: Current studies are investigating second-generation JAK-Inh for GVHD (149), several of which have already been FDA approved for the treatment of autoimmune diseases (E.g. Baricitinib, JAK1/2-inh, for RA (150); Upadacitinib, JAK1-Inh, for RA (151); and the not FDA approved Filgotinib, JAK1-Inh (152)) (153).