Inclusion Criteria:  Recipient of allogeneic hematopoietic stem cell transplantation Participants must have steroid-refractory cGVHD and had obtained a partial response after at least 12 weeks of treatment with ruxolitinib. Steroid-refractory cGVHD is defined as having persistent signs and symptoms of cGVHD despite the use of prednisone at ≥ 0.25 mg/kg/day (or 0.5 mg/kg every other day) for at least 4 weeks (or equivalent dosing of alternate glucocorticoids) without complete resolution of signs and symptoms. Stable dose of glucocorticoids for 4 weeks prior to enrollment. No addition or subtraction of other immunosuppressive medications (e.g., calcineurin-inhibitors, sirolimus, mycophenolate-mofetil) for 4 weeks prior to enrollment. The dose of immunosuppressive medicines may be adjusted based on the therapeutic range of that drug. No age limit. In the case of children participating in the study, the informed consent will be signed by a parents or legal guardians. Eastern Cooperative Oncology Group scale performance status 0-2 Participants must have adequate organ function Women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately. Ability to understand and the willingness to sign a written informed consent document  Exclusion Criteria:  Ongoing prednisone requirement >1 mg/kg/day (or equivalent). Concurrent use of calcineurin-inhibitor plus sirolimus (either agent alone is acceptable). History of active thrombotic microangiopathy, hemolytic-uremic syndrome or thrombotic thrombocytopenic purpura in the last 6 months. New immunosuppressive medication in the 4 weeks prior to enrollment. Extra-corporeal Photopheresis or rituximab therapy in the 4 weeks prior to enrollment. Post-transplant exposure to T-cell or interleukin-2 targeted medication within 100 days prior to enrollment. Donor lymphocyte infusion within 100 days prior to enrollment. Active malignant relapse. Active uncontrolled infection. Organ transplant (allograft) recipient. HIV-positive individuals on combination antiretroviral therapy are ineligible. Individuals with active uncontrolled hepatitis B or C are ineligible as they are at high risk of lethal treatment-related hepatotoxicity after hematopoietic stem cell transplant. Other investigational drugs within 4 weeks prior to enrollment, unless cleared by the Principal Investigator. Pregnant women are excluded from this study.