A recent study using immune cells from the peripheral blood of RA patients reported that the selective JAK1 inhibitor filgotinib inhibited the IFN-α and IL-6 signaling pathways to a similar extent as other JAK inhibitors, while it inhibited IFN-γ signaling and JAK2-mediated pathways to a lesser extent [35]. Here, JAK1 is linked to rheumatoid arthritis.