BMS-066 is an IKKβ/Tyk2 pseudokinase inhibitor. With IC50s of 9 nM and 72 nM, respectively.

TYK2:72 nM, IKKβ:9 nM

BMS-066 is shown to inhibit IKKβ-catalyzed phosphorylation of IKKβ in vitro with an IC50 of 9 nM and is more than 500-fold selective for IKKβ over the closely related IKKα. For the six kinases showing more than 75% inhibition at 10 μM, IC50 values are determined in dose-response assays and BMS-066 is shown to be more than 30-fold selective against even the next most potently inhibits kinase (Brk). BMS-066 shows IC50 values of 72 and 1020 nM against the Tyk2 pseudokinase domain probe displacement and IL-23-stimulated reporter assays, respectively[2]. To understand the selectivity on a more comprehensive scale, BMS-066 is assayed against 155 additional kinases at 10 μM, and only six of these kinases are inhibited more than 75%. This indicates that BMS-066 is more than 400-fold selective for IKKβ over more than 95% of the kinases tested. BMS-066 inhibits LPS-stimulated cytokine production in human peripheral blood mononuclear cells, both at the protein and message level, with IC50 values of approximately 200 nM against these endpoints and it also inhibits the IKKβ-catalyzed phosphorylation of IkBα in LPS stimulated cells with a similar IC50 value[1].

Clear reduction of inflammation is also evident in the low dose of BMS-066 (5 mg/kg) and the bone resorption seems to be more focal and less severe compared with the control. The joints from animals receiving 10 mg/kg BMS-066 are normal or show minimal changes in both inflammation and bone resorption. Bone density measurements also show a clear dose-dependent benefit of treatment with BMS-066. Microcomputed tomography of the hind limbs also show that BMS-066 provides a dose-dependent protection against the pitting, loss of bone mass, woven porous bone, and fusion of the small bones evident in the rats. Serum drug level measurements in satellite animals on the first day of dosing show that a single dose provides coverage for approximately 3 h (6 h daily with twice daily dosing) of the mouse whole-blood IC50 value against LPS-induced TNF-α. It is also showed that IKKβ inhibitors suppress TNF-α and IL-1β production within these tissues in experimental arthritis model[1].