This study was a single arm, open label, multicenter phase Ib / II trial in subjects with glucocorticoid refractory / dependent moderate to severe cGVHD.The trial consisted of two phases: phase I for the dose exploration and phase II for the extension study.

Inclusion Criteria:

• Understood and signed an informed consent form.
• ≥18 years old, Karnofsky Performance Scale of ≥60, life expectancy ≥ 6 months.
• Has received allogeneic hematopoietic stem cell transplantation (alloSCT).
• Clinically diagnosed moderate to severe cGVHD according to NIH Consensus Criteria.
• Has received systemic or topical corticosteroids therapy and confirmed steroid-refractory/dependent cGVHD according to NIH Consensus Criteria.
• Has received at least 1 lines of therapy for cGVHD.
• Adequate laboratory indicators.
• No pregnant or breastfeeding women, and a negative pregnancy test.

Exclusion Criteria:

• Has active acute GVHD.
• Has previously failed to respond to JAK inhibitors for GVHD, or who had used JAK inhibitors within 4 weeks before the first administration.
• Has uncontrollable active infections or infections requiring systematic treatment within 7 days before the first administration.
• Development of other basic diseases.
• Has malignant tumors within 3 years.
• Has multiple factors affecting oral medication.
• Has substance abuse or a psychotic disorder.
• Has severe and / or uncontrolled disease.
• Allergic to drugs or its constituents.
• Has participated in any other clinical trials within 4 weeks before first administration.
• According to the judgement of the investigators, there are other factors that may lead to the termination of the study.