PF-06651600 is a novel potent, selective JAK3 inhibitor with IC50 of 0.346 nM, displays >1,000-fold selectivity over JAK1 and JAK2; inhibits Th1 and Th17 cell differentiation and function, reduces disease pathology in rat adjuvant-induced arthritis as well as in mouse experimental autoimmune encephalomyelitis models; selectively targets γc cytokine pathways while preserving JAK1-dependent anti-inflammatory signaling such as the IL-10 suppressive functions following LPS treatment in macrophages and the suppression of TNFα and IL-1β production in IL-27-primed macrophages.Rheumatoid ArthritisPhase 2 Clinical

Ifidancitinib (ATI-50002) is a specific JAK kinase 1/3 inhibitor that induces hair growth in AA-affected C3H/HeJ mice.Ifidancitinib can be used to study autoimmune diseases.

Tofacitinib (CP-690550) is a potent, specific, orally active inhibitor of JAK3 with IC50 of 1 nM in cell-free assays; displays 20- to 100-fold less potency for JAK2 and JAK1 (IC50=20 nM and 112 nM, respectively).