JAK3-IN-1 is an orally active, selective and potent JAK3 inhibitor that can be used to study immune system diseases.

FLT3 (Enzymatic assays):13 nM, TXK (Enzymatic assays):36 nM, BLK (Enzymatic assays):157 nM, JAK2:1050 nM, JAK3-dependent Ba/F3 cells:69 nM, JAK1:896 nM, TTK (Enzymatic assays):49 nM, BTK:794 nM, EGFR (WT):409 nM, ITK:1070 nM, TYK2:>10000 nM, JAK3:4.8 nM

JAK3-IN-1 (Compound 9) is a potent inhibitor of JAK3 with potential off-target effects on fms-related tyrosine kinase 3 (FLT3) and several tyrosine protein kinases (TEC family kinases).JAK3-IN-1 selectively inhibited the proliferation of JAK3-dependent Ba/F3 cells (IC50 = 69 nM) and showed no antiproliferative activity against other JAK-dependent Ba/F3 cells at concentrations below 3 0 μM. JAK3-IN-1 selectively inhibited the proliferation of JAK3-dependent Ba/F3 cells (IC50 = 69 nM), whereas for other JAK-dependent Ba/F3 cells, it did not show antiproliferative activity at concentrations lower than 3.0 μM.JAK3-IN-1 showed minimal inhibitory effects on other JAK kinases and wild-type EGFR (EGFRWT), which was consistent with its more than 180-fold higher IC50 values against EGFRWT and TYK2 (409 nM and >10,000 nM, respectively). The IC50 values of JAK3-IN-1 for BTK and ITK were 794 nM and 1070 nM, respectively, indicating that its inhibitory effect was more than 165-fold lower than that of JAK3.
Treatment of BMDM cells with JAK3-IN-1 (500 nM, 3 h) in the concentration range of 0-5 μM completely blocked IL-4-induced p-STAT6 but only partially inhibited IFNβ-induced p-STAT1 at 5.0 μM. Enzymatic assays (using Z'-lyte or LanthaScreen formats) validated the inhibitory effect of JAK3-IN-1 on BTK and ITK. LanthaScreen format) verified the enzymatic inhibition of FLT3 (IC50 = 13 nM), TTK protein kinase (TTK, IC50 = 49 nM), BLK proto-oncogene (BLK, IC50 = 157 nM), and TXK tyrosine protein kinase (TXK, IC50 = 36 nM) by JAK3-IN-1. [1]

In mice, 8 days of oral treatment with JAK3-IN-1 (75 mg/kg once daily) resulted in no significant changes in the number of B and T cells but a decrease in the number of NK cells in the tumor-loaded lungs and spleens, and JAK3-IN-1 exhibited good pharmacokinetic properties, with a T1/2 half-life of 1.4 hours and an area under the curve (AUC) of 1.4 hours at the 10 mg/kg oral dose. JAK3-IN-1 showed good pharmacokinetic properties, with a half-life (T1/2) of 1.4 hours, an area under the curve (AUC) of 795 ng-h/mL after 10 mg/kg oral dose, and an oral bioavailability of 66%. [1]