After conducting pilot phase, the study team decided to stop the study as the study couldn't meet the study target number of patients and study objectives.

The purpose of this study is to evaluate the effectiveness of ibrutinib compared to conventional salvage treatments in participants with steroid dependent/refractory chronic graft versus host disease (cGVHD) by measuring overall cGVHD response (modified National Institutes of Health [NIH] response defined complete response [CR] and partial response [PR]) at Week 24.

Inclusion Criteria:

Part A and Part B

• Must have a confirmed diagnosis of steroid dependent or refractory classic cGVHD defined at any time post-hematopoietic cell transplantation (HCT) as: a) refractory disease - progressive cGVHD manifestations requiring prednisolone at greater than or equal to (>=) 1 milligram per kilogram per day (mg/kg/day) for at least 1 week or persist without improvement despite continued treatment with glucocorticoid (prednisolone at >= 0.5 mg/kg/day or 1 mg/kg every other day) for at least 4 weeks; b) dependent disease: persistent cGVHD manifestations requiring glucocorticoid >= prednisolone 0.25 mg/kg/day or >=0.5mg/kg every other day for at least 8 weeks Part A
• Treated at least 2 or more therapies for cGVHD (including glucocorticoids)
• Participants whose identified last line of conventional salvage treatment is second-fourth line of therapy
• Index date (initiation date of the identified last-line of conventional salvage therapy) at least 28 weeks before the study initiation date Part B
• Treated at least 3 lines therapies for cGVHD (including glucocorticoids)
• Participants who are treated with ibrutinib in their second-fourth line of therapy

Exclusion Criteria:

Part A and Part B

• Known or suspected active acute GVHD
• Received an investigational drug (including investigational vaccines) or used an invasive investigational medical device within 28 days Part A
• Treated with an investigational agent for their identified last-line of conventional salvage therapy
• Pregnant, breastfeeding during last-line of conventional salvage therapy Part B
• Pregnant, breast-feeding, or of childbearing potential without a negative serum or urine pregnancy test within 7 days of enrollment. Male or female participants of childbearing potential unwilling to use effective contraceptive precautions throughout the trial

Participants with steroid dependent or refractory chronic graft versus host disease (cGVHD) will be included.