A potent, selective, ATP competitive JAK2 inhibitor with Ki of 0.26 nM; demonstrates significant JAK2 selectivity over JAK3 and marginal selectivity over JAK1; blocks STAT3 phosphorylation in a panel of human solid tumor cell lines, potently inhibits the growth of the TEL-Jak2 cell line (GI50=60 nM); suppresses the growth of human solid tumor xenografts harboring persistent Stat3 activity.Liver Cancer Phase 1 Discontinued.