Several other JAK inhibitors are being developed with the aim to treat RA, among them some are in preclinical, as filgotinib (a JAK1/2 inhibitor, GLPG0634) [209], AG490 (a JAK2 inhibitor) [210], CEP-33779 (a JAK2 inhibitor) [211] or already in clinical development, as baricitinib (a JAK1/2 inhibitor, LY-3009104 or INCB028050) [212, 213] and decernotinib (a selective JAK3 inhibitor, VX-509) [214]. This evidence concerns the gene JAK2 and rheumatoid arthritis.