A Randomized Phase II Study to Compare the Potential Long-Lasting Positive Effect of Decidual Stromal Cells to the Best Available Treatment in Graft Versus Host Disease

Will vary depending upon Investigator's choice identified prior to randomization. Dose and frequency will depend on label (where approved) and institutional guidelines for various BAT. No cross-over to DSC treatment is planned. The BAT in this study will freely be identified by the Investigator prior to patient randomization and may include treatments such as: anti-thymocyte globulin (ATG), extracorporeal photopheresis (ECP), low-dose methotrexate (MTX), mTOR inhibitors (everolimus or sirolimus), vedolizumab, ruxolitinib.

The dose will be 1×106 DSC/kg bodyweight, at least 2 doses at least one week apart. Within the first 28 days, patients meeting criteria of aGvHD disease progression, mixed response or no response, may be given additional weekly doses of DSC until satisfactory response (ie: CR) are reached (max 4 doses in total).