BIIB068 is an selective, reversible and orally active BTK inhibitor (IC50 = 1 nM, Kd = 0.3 nM). BIIB068 is 400 times more selective for BTK than other kinases.

BTK:0.3 nM (Kd), BTK:1 nM (IC50)

BIIB068 inhibits B cell, neutrophil and monocyte activation in vitro, but not T cell responses.

BIIB068 demonstrated good PK/PD correlation with in vivo EC50 = 0.16 μM based on antibody esponse, similar to in vivo WB pBTK potency in mice. BIIB068 exhibited no adverse effects in the single dose CNS and respiratory studies in rats nor in a single dose cardiovascular study in monkeys. BIIB068 was well tolerated and effective at inhibiting BTK phosphorylation in healthy subjects.