ROCKnrol-1: This study is evaluating how safe and effective Belumosudil in combination with corticosteroids is in people aged 12 years and over with newly diagnosed chronic Graft Versus Host disease (cGVHD)A Randomized, Double-blind, Multicenter, Phase 3 Study to Evaluate Efficacy and Safety of Belumosudil in Combination With Corticosteroids Versus Placebo in Combination With Corticosteroids in Participants at Least 12 Years of Age With Newly Diagnosed Chronic Graft Versus Host Disease (cGVHD)

Exclusion

Participants are excluded from the study if any of the following criteria apply:

Medical conditions

• Histological relapse of the underlying disease after most recent allogeneic HCT
• Post-transplant lymphoproliferative disease within 4 weeks prior to randomization
• Female participants who are pregnant or breastfeeding
• Unable to tolerate a prednisone equivalent dose of corticosteroids ≥ 1 mg/kg/day Prior/concomitant therapy
• Participant has had previous exposure to belumosudil.
• Received any previous systemic treatment for cGVHD with the following exception: Corticosteroids for cGVHD received within 7 days prior to the planned administration of IMP only if in the interest of participant.

Prior/concurrent clinical study experience

• Received any investigational agents, or any investigational device or procedure, or prohibited therapy for this study within 28 days or 5 elimination half-lives prior to randomization, whichever is longer Diagnostic assessments
• Karnofsky (if aged ≥16 years)/Lansky (if aged <16 years) Performance Score of < 60
• Platelets <50 x 109/L. Platelet transfusion is not allowed within 3 days before the screening hematological test
• Absolute neutrophil count (ANC) <1.0 x 109/L. The use of granulocyte-colony stimulating factor (G-CSF) is not allowed to reach this level during screening
• Estimated Glomerular Filtration Rate (eGFR) <30 mL/min/1.73 m2 using the MDRD-4 variable formula (if aged ≥18 years) or using the Bedside Schwartz formula (if aged <18 years)
• Aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) >3 x ULN without liver cGVHD (or >5 × ULN if due to cGVHD with liver cGVHD)
• Total bilirubin >1.5 × (ULN) (>3 × ULN if Gilbert syndrome)
• Participant has forced expiratory volume in 1 second (FEV1) of predicted ≤39% or has lung score of 3 according to NIH consensus diagnostic and staging criteria (2014)
• History or other evidence of severe illness or any other conditions that would make the participant, in the opinion of the Investigator, unsuitable for the study (such as malabsorption syndromes, poorly controlled psychiatric disease or coronary artery disease)
• Known history of human immunodeficiency virus (HIV)
• Active viral disease including hepatitis B virus (HBV) or hepatitis C virus (HCV)
• Active uncontrolled cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infection. Infections are considered controlled if appropriate therapy has been instituted and, at the time of screening, no signs of infection worsening are present according to Investigator's judgement
• Diagnosed or treated for another malignancy other than the underlying disease allogeneic HCT was indicated for, within 3 years prior to randomization with the exception of complete resection of basal cell carcinoma or squamous cell carcinoma of the skin, an in-situ malignancy, or low risk prostate cancer after curative therapy
• Unable to swallow tablets
• Participant not suitable for participation, whatever the reason, as judged by the Investigator, including medical or clinical conditions, or participants potentially at risk of noncompliance to study procedures