Two-year safety outcomes of iPS cell-derived mesenchymal stromal cells in acute steroid-resistant graft-versus-host disease.

The first completed clinical trial of induced pluripotent stem cell (iPS cell)-derived cells was conducted in 15 participants with steroid-resistant acute graft-versus-host disease. After intravenous infusion of mesenchymal stromal cells (CYP-001 derived from a clone of human iPS cells), we reported the safety, tolerability and efficacy within the primary evaluation period at day 100. We now report results at the 2-year follow-up: 9 of 15 (60%) participants survived, which compares favorably with previously reported outcomes in studies of steroid-resistant acute graft-versus-host disease. Causes of death were complications commonly observed in recipients of allogeneic hematopoietic stem cell transplantation, and not considered by the investigators to be related to CYP-001 treatment. There were no serious adverse events, tumors or other safety concerns related to CYP-001. In conclusion, systemic delivery of iPS cell-derived cells was safe and well tolerated over 2 years of follow-up, with sustained outcomes up to 2 years after the first infusion. ClinicalTrials.gov registration: NCT02923375 .