Study of the Bruton's Tyrosine Kinase Inhibitor in Subjects With Chronic Graft Versus Host Disease

* Steroid dependent or refractory classic chronic GVHD disease. * No more than 3 previous treatments for cGVHD. * Receiving baseline systemic glucocorticoid therapy (at stable dose) for cGVHD at study entry. * Men and women ≥18 years old. * Karnofsky performance status ≥60.

* Known or suspected active acute GVHD. * Current treatment with sirolimus AND either cyclosporine or tacrolimus. * History of treatment with a tyrosine kinase inhibitor (eg, imatinib), purine analogs or other cancer chemotherapy in the 4 weeks prior to starting study drug. * Currently active, clinically significant cardiovascular disease. * Uncontrolled infections not responsive to antibiotics, antiviral medicines, or antifungal medicines or a recent infection requiring systemic treatment that was completed ≤14 days before the first dose of study drug. * Progressive underlying malignant disease including post-transplant lymphoproliferative disease. * History of other malignancy (not including the underlying malignancy that was the indication for transplant) * Concomitant use of warfarin or other Vitamin K antagonists * Known bleeding disorders or hemophilia. * History of stroke or intracranial hemorrhage within 6 months prior to enrollment. * Known history of human immunodeficiency virus (HIV) or active with hepatitis C virus (HCV) or hepatitis B virus (HBV). * Concurrent use of a strong cytochrome P450(CYP) 3A inhibitor.