From the date of randomization to the date of any predefined event, whichever occurs first

The proportion of responders and its 95% confidence interval (using exact binomial methods) will be calculated.

PK parameter (AUC at steady state)

Proportion of participants who achieve an overall response (partial response \[PR\] or complete response \[CR\]) with up to 24 weeks of therapy (i.e. by the Week 25 or Cycle 7 Day 1 visit whichever is first), as defined by the National Institute of Health (NIH) Consensus response criteria

24-week ORR defined as the proportion of participants achieving BOS complete response (CR) or partial response (PR) based on change in FEV1 measurement per criteria of the 2014 NIH Consensus Conference.

24-week ORR defined as the proportion of participants achieving BOS complete response (CR) or partial response (PR) based on change in FEV1 measurement per criteria of the 2014 NIH Consensus Conference.

24-week progression rate is defined as the proportion of participants experiencing BOS progression based on change in FEV1 measurement per criteria of the 2014 NIH Consensus Conference.

DOR is defined as time from first documentation of response to time of first documentation of deterioration from best response (e.g., complete response \[CR\] to partial response \[PR\], or PR to Lack of response \[LR\]). As per the 2014 National Institutes of Health (NIH) Consensus Development Project for clinical trials in cGVHD criteria: CR was defined as resolution of all manifestations of cGVHD in each organ or site.PR was defined as the improvement in at least 1 organ or site without progression in any other organ or site.LR included response status of mixed, unchanged, or progression.Mixed LR was defined as complete or partial response in at least 1 organ accompanied by progression in another organ. Unchanged LR was defined as outcomes that did not meet criteria for CR, PR, progression or mixed response. Progression LR was defined as progression in at least 1 organ or site without a response in any other organ or site. Confidence interval (CI) is calculated using Kaplan-Meier method.

The questionnaire asked participants to indicate the degree of bother that they experienced due to symptoms in 7 domains potentially affected by cGVHD. It consists of 30 items of 7 domains: skin, eyes and mouth, breathing, eating and digestion, muscles and joints, energy, and mental and emotional. Each question was rated/scored as 0-not at all, 1-slightly, 2-moderately, 3-quite a bit, 4-extremely with lower values representing better outcome. A domain score was calculated for each domain by taking the mean of all items completed if more than 50% were answered and normalizing to a 0 to 100 scale. A total score was calculated as average of all non-missing domain scores if more than 50% of them were non-missing, ranged from 0-100. A higher score indicated more bothersome symptoms. A 7-point difference on the total score of cGVHD symptom scale was found to be clinically meaningful.

The questionnaire asked participants to indicate the degree of bother that they experienced due to symptoms in 7 domains potentially affected by cGVHD. It consisted of 30 items of 7 domains: skin, eyes and mouth, breathing, eating and digestion, muscles and joints, energy, and mental and emotional. Each question was rated/scored as 0-not at all, 1-slightly, 2-moderately, 3-quite a bit, 4-extremely with lower values representing better outcome. A domain score was calculated for each domain by taking the mean of all items completed if more than 50% were answered and normalizing to a 0 to 100 scale. A total score was calculated as average of all non-missing domain scores if more than 50% of them were non-missing, ranged from 0-100. A higher score indicated more bothersome symptoms. A 7-point difference on the total score of cGVHD symptom scale was found to be clinically meaningful. Mean of duration of \>=7PtR is presented.

The TTNT was measured as the time from first treatment to the time of new systemic cGVHD treatment, censored by last response assessment or long term follow up assessment, whichever was the latest and available. TTNT was analyzed by the Kaplan-Meier survival method.

FFS was defined as the absence of new cGVHD systemic therapy, non-relapse mortality and recurrent malignancy (i.e. underlying disease) and was censored by last response assessment or long term follow up assessment, whichever was the latest and available. Kaplan-Meier method was used for the analysis.

OS was defined as time from first dose of belumosudil to the date of death due to any cause. CI was calculated using Kaplan-Meier method.

As per the 2014 NIH Consensus Development Project for clinical trials in cGVHD criteria: CR was defined as resolution of all manifestations of cGVHD in each organ or site. PR was defined as the improvement in at least 1 organ or site without progression in any other organ or site.

The best response (CR, PR) for individual organs (skin, eyes, mouth, esophagus, upper gastrointestinal \[GI\], lower GI, liver, lungs, joints and fascia) was summarized. As per the 2014 NIH Consensus Development Project for clinical trials in cGVHD criteria, CR was defined as resolution of all manifestations of cGVHD in each organ or site. PR was defined as the improvement in at least 1 organ or site without progression in any other organ or site.

Change in corticosteroid doses was analyzed by using prednisone dose equivalents. If participants were not using prednisone as the systemic corticosteroid, then the prednisone dose equivalent would be determined according to following conversion ratios: 1 mg prednisone is equivalent to: 4.0 mg Hydrocortisone; 0.8 mg Methylprednisolone; 0.15 mg Dexamethasone; 1.0 mg Prednisolone and 0.8 mg Triamcinolone. Baseline was defined as the valid and last non-missing value obtained within 28 days prior to participant receiving the first study drug in parent study (KD025-208 \[NCT02841995\] or KD025-213 \[NCT03640481\]).

The GSR assessment was performed by asking the participants to rate their disease severity of cGVHD symptoms on a 0 to 10-point numeric rating scale, where score 0 indicated 'not at all severe cGVHD symptoms' and score 10 indicated 'most severe cGVHD symptoms possible'. The response was defined using scores from 9 organs: skin, eyes, mouth, esophagus, upper GI track, lower GI tract, liver, lungs, and joints and fascia plus GSR. Baseline was defined as the valid and last non-missing value obtained within 28 days prior to participant receiving the first study drug in parent study (KD025-208 \[NCT02841995\] or KD025-213 \[NCT03640481\]). Maximal improvement from Baseline was calculated as lowest GSR score on scheduled visits minus GSR score at Baseline with possible ranges from -10 to 10. The lower the number means the better improvement in cGVHD symptoms.

An adverse event (AE) was defined as any untoward medical occurrence in a clinical trial participant associated with the use of a study drug, whether or not considered drug-related. Serious adverse event (SAE) was any untoward medical occurrence that at any dose: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, was a congenital anomaly/birth defect or was an important medical event. The severity of each AE was graded using the Common Terminology Criteria for Adverse Events version 4.03 scale. TEAEs were defined as AEs that developed, worsened or became serious during the TE period.

OR was defined as the percentage of participants with complete response (CR) or partial response (PR). The OR determination of chronic graft versus host disease (cGVHD) was based on cGVHD response assessment performed by clinicians as per the 2014 National Institutes of Health (NIH) Consensus Development Project for Clinical Trials in cGVHD criteria. CR was defined as the resolution of all manifestations in each organ or site. PR was defined as the improvement in at least 1 organ or site without progression in any other organ or site; and cGVHD progression was defined as the clinically meaningful worsening in 1 or more organs regardless of improvement in other organs.

An adverse event (AE) was defined as any untoward medical occurrence in a participant who received study drug and did not necessarily have to have a causal relationship with the treatment. Serious adverse events (SAEs) was any untoward medical occurrence that at any dose: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect, was a medically important event. TEAEs were defined as AEs that developed, worsened or became serious during the TEAE period (defined as the time from the first dose of study drug up to 28 days after the last dose of study drug). TEAEs included both SAEs and non-SAEs.

Area under the plasma concentration versus time curve until the time of last quantifiable concentration

Maximum plasma concentration observed

Area under the curve from time 0 to the time of last measurable concentration

Area under the curve from time 0 extrapolated to infinity