A potent and highly selective JAK3 inhibitor with IC50 of 0.15 nM; dispalys >4,300-fold selectivity over JAK1, JAK2 and TYK2, and other kinases BMX, EGFR, ITK and BTK; blocks cytokine signaling through JAK3, but not through other JAK family enzymes; inhibits IL-7 induced pSTAT5 in CD3+, CD8+ T cells with IC50 of 280 nM; sufficiently blocks the development of inflammation in a rat model of rheumatoid arthritis, while sparing hematopoiesis.
