CK0802 for Treatment of Steroid Refractory Graft vs. Host Disease (GVHD)

Inclusion Criteria: * 1\. Age ≥12 years old (first 3 subjects will be ≥ 18 years) * 2\. Grade 2-4 acute GVHD (aGVHD) at baseline * 3\. No other prior aGVHD treatment * 4\. Steroid Refractory * Progressed after 3 days of treatment with 2 mg/kg methylprednisolone (MPE) * No improvement after 7 days of treatment with 2 mg/kg MPE * Progressed to a new organ after treatment with 1 mg/kg MPE for skin or upper gastrointestinal (UGI) aGVHD * Progressed from nadir during or after a steroid taper * 5\. Female subjects of childbearing potential (FPCP) must have a negative urine or serum pregnancy test. * 6\. Agreed to abide by all protocol required procedures including study-related assessments, visits and long term follow up. * 7\. Willing and able to provide written informed consent. * 8\. Signed informed consent Exclusion Criteria: * 1\. 30 days prior treatment with any other investigational agent after allogeneic HSCT. * 2\. Known HIV seropositivity. * 3\. Uncontrolled infection, not responding to appropriate antimicrobial agents after seven days of therapy. The Protocol PI is the final arbiter of eligibility. * 4\. Subjects with uncontrolled inter-current illness that in the opinion of the investigator would place the subject at greater risk of severe toxicity and/or impair the activity of CK0802. * 5\. Subjects who are pregnant or breastfeeding.