WHI-P97 HCl is a potent and selective JAK-3 inhibitor. WHI-P97 had an estimated Ki value of 0.09 microM from modeling studies and a measured IC50 value of 2.5 microM in EGFR kinase inhibition assays. WHI-P97 effectively inhibited the in vitro invasiveness of EGFR-positive human cancer cells in a concentration-dependent manner.

WHI-P97 is a potent inhibitor of Janus kinase (JAK)-3.?Treatment of mast cells with WHI-P97 inhibited the translocation of 5-lipoxygenase (5-LO) from the nucleoplasm to the nuclear membrane and consequently 5-LO-dependent leukotriene (LT) synthesis after IgE receptor/FcepsilonRI crosslinking by >90% at low micromolar concentrations.?WHI-P97 did not directly inhibit the enzymatic activity of 5-LO, but prevented its translocation to the nuclear membrane without affecting the requisite calcium signal.Therapeutic WHI-P97 concentrations, which inhibit mast cell leukotriene synthesis in vitro, could easily be achieved in vivo after the i.v. or i.p. administration of a single nontoxic 40 mg/kg bolus dose of WHI-P97.

WHI-P97 was very well tolerated in mice, with no signs of toxicity at dose levels ranging from 5 microg/kg to 50 mg/kg, and LD(10) was not reached at a 50 mg/kg dose level when administered as a single i. p. or i.v. bolus dose.??WHI-P97 showed promising biological activity in a mouse model of allergic asthma at nontoxic dose levels.?Treatment of ovalbumin-sensitized mice with WHI-P97 prevented the development of airway hyper-responsiveness to methacholine in a dose-dependent fashion.?Furthermore, WHI-P97 inhibited the eosinophil recruitment to the airway lumen after the ovalbumin challenge in a dose-dependent fashion.