SYK and rheumatoid arthritis: Janus Kinase (JAK) inhibitors (tofacitinib, baricitinib, upadacitinib, and filgotinib), spleen tyrosine kinase (SyK) inhibitors such as fostamatinib and mitogen-activated protein kinase (MAPK) inhibitors (talmapimod) show promising results in the treatment of RA patients who have failed to respond adequately to csDMARD and bDMARD [61,62,63,64].