Long-Term Follow-Up of a Pilot Study Using Placenta-Derived Decidua Stromal Cells for Severe Acute Graft-versus-Host Disease

•All 21 patients treated for severe acute graft-versus-host disease with decidua stromal cells (DSCs) responded by day 28.•One-year survival in DSC-treated patients was 81%.•Four-year survival in DSC-treated patients was 57%. There is a need for effective therapy with few side effects for severe acute graft-versus-host disease (GVHD). The placenta protects the fetus from the mother's haploidentical immune system during pregnancy. We found that maternal stromal cells from the fetal membrane, so-called decidua stromal cells (DSCs), are more immunosuppressive than other sources of stromal cells. We prospectively treated 21 patients (median age, 49 years; range, 1.6 to 72 years) for grade II-IV acute GVHD. All 21 patients had biopsy-proven gastrointestinal GVHD. The majority of patients were either steroid-refractory or had progressive GVHD, 11 patients after >7 days or with progression after 3 days, and 10 were refractory to steroids after >3 days. We used an improved protocol in which DSCs were thawed and infused in a buffer with 5% human albumin. DSCs were given at a median dose of 1.2 (range, 0.9 to 2.9) × 106 cells/kg body weight with a median of 2 (range, 1 to 6) doses, given 1 week apart. The median viability of thawed DSCs was 93% (range, 69% to 100%), and the median cell passage number was 4 (range, 2 to 4). Complete resolution of GVHD was seen in 11 patients, with a partial response in the other 10. The cumulative incidence of chronic GVHD was 52%. GVHD was mild in 6 patients, moderate in 4 patients, and severe in 1 patient based on National Institutes of Health chronic GVHD severity scoring. Nine patients died, including 3 from relapse and 1 each from acute GVHD and septicemia, Zygomycetes infection, liver insufficiency, cerebral hemorrhage, multiple organ failure, and chronic GVHD with obstructive bronchiolitis. Four-year transplantation-related mortality was 28.6%, and overall survival was 57%. Survival was similar (P = .33) to that for all 293 patients who underwent allogeneic hematopoietic cell transplantation during the same period (2012 to 2015), with 66% overall survival. DSC infusion is a novel therapy for acute GVHD grade II-IV, and a randomized trial is currently underway (ClinicalTrials.gov NCT 02172937).