Update on stem cell transplantation for systemic sclerosis: recent trial results

Systemic sclerosis (SSc) is a heterogeneous condition characterized by the deposition of excess collagen in skin and internal organs due to vasculopathy, immune activation, low grade inflammation, and fibrosis. Progressive diffuse cutaneous SSc with organ involvement has a poor prognosis. The employment of autologous hematopoietic stem cell transplantation (HSCT) as a means to escalate immunosuppressive therapy has resulted in rapid and sustained improvement of skin thickening and functional ability, stabilization of major organ function with some improvement of vital capacity in pilot studies, registry analyses, and the phase II ASSIST trial. Results from the phase III ASTIS trial corroborate these findings and show long-term survival benefit of HSCT. The ASTIS and SCOT trials will determine whether the benefits of HSCT outweigh the risks of serious adverse events including treatment-related mortality of around 6-10% and potential long-term complications. Better patient selection and safer transplant regimens may improve the outcome of HSCT for SSc.