Safety and Efficacy of Oral Belumosudil in Black or African American, American Indian or Alaska Native, and Native Hawaiian or Other Pacific Islander Male and Female Participants Aged 12 Years and Above With Chronic Graft Versus Host Disease (cGVHD) After At Least 2 Prior Lines of Systemic Therapy

Inclusion Criteria: * Participants are included in the study if any of the following criteria apply: * Participant is Black or African American, or American Indian or Alaska Native, or Native Hawaiian or Other Pacific Islander by self-identification. * Previously received at least 2 and not more than 5 lines of systemic therapy for cGVHD. * Receiving glucocorticoid therapy with a stable dose over the 2 weeks prior to screening. * Have persistent cGVHD manifestations and systemic therapy is indicated. * Karnofsky (if aged ≥ 16 years) / Lansky (if aged \< 16 years) Performance Score of ≥ 60. * At least 12 years of age; weight ≥ 40 kilograms (kg). * Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 3 x upper limit of normal (ULN). * Total bilirubin ≤ 1.5 x ULN. * Contraception (with double contraception methods) for male and female participants; not pregnant or breastfeeding for female participants * Capable of giving signed informed consent. Exclusion Criteria: * Participants are excluded from the study if any of the following criteria apply: * Participant has not been on a stable dose/regimen of systemic cGVHD treatment(s) for at least 2 weeks prior to screening. (Note: Concomitant corticosteroids, calcineurin inhibitors, sirolimus, MMF, methotrexate, rituximab, and ECP are acceptable. Systemic investigational GVHD treatments are not permitted). * Histological relapse of the underlying cancer or post-transplant lymphoproliferative disease at the time of …