A Study to Investigate Safety of Belumosudil in Participants Aged 12 Years and Above, With Chronic Graft-versus-host Disease (cGVHD)

Inclusion Criteria: * Male or female patients at least 12 years of age inclusive, at the time of signing the informed consent * Participants who had an allogeneic hematopoietic cell transplantation (HCT) * Previously received at least 2 prior lines of systemic therapy for cGVHD * Received glucocorticoid therapy with a stable dose over the 2 weeks prior to screening * Had persistent cGVHD manifestations and systemic therapy was indicated * Karnofsky (if aged ≥ 16 years)/Lansky (if aged \<16 years) Performance Score of ≥ 60 * Capable of giving signed informed consent as described in the protocol Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: * Absolute neutrophil count ≤1.5 X 109/L * Platelet count ≤ 50 X 109/L * Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≥ 3 X upper limit of normal (ULN) (\>5 × ULN if due to cGVHD) * Total bilirubin ≥ 1.5 X ULN * Glomerular filtration rate (GFR) ≤ 30 mL/min/1.73m3 * Positive hepatitis B surface antigen, or hepatitis C antibody or HIV antibody at screening * FEV1 ≤39% or has lung score of 3 The above information is not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.