Study of Efficacy and Safety of Ruxolitinib in Chinese Participants With Corticosteroid-refractory Chronic Graft vs. Host Disease

Inclusion Criteria: * Signed informed consent must be obtained prior to participation in the study. * Male or female Chinese participants aged 12 or older at the time of informed consent * Able to swallow tablets.- Have undergone alloSCT from any donor source (matched unrelated donor, sibling, haplo-identical) using bone marrow, peripheral blood stem cells, or cord blood. Recipients of non-myeloablative, myeloablative, and reduced intensity conditioning are eligible. * Evident myeloid and platelet engraftment: * Absolute neutrophil count (ANC) \>1,000/mm3 AND * Platelet count ≥25,000/mm3 Note: Use of growth factor supplementation and transfusion support is allowed during the trial, however, transfusion to reach a minimum platelet count for inclusion is not allowed during screening and at baseline. * Participants with clinically diagnosed cGvHD staging of moderate to severe according to NIH Consensus Criteria (Jagasia et al 2015) prior to Cycle 1 Day 1. * Moderate cGvHD: at least one organ (not lung) with a score of 2, 3 or more organs involved with a score of 1 in each organ, or lung score of 1. * Severe cGvHD: at least 1 organ with a score of 3, or lung score of 2 or 3. * Participants currently receiving systemic corticosteroids for the treatment of cGvHD for a duration of \< 12 months prior to Cycle 1 Day 1, and have a confirmed diagnosis of corticosteroid refractory cGvHD defined per 2014 NIH consensus criteria (Martin et al 2015) irrespective of the concomita…