Should We Use Extracorporeal Photopheresis More Often? Evidence From Graft-Versus-Host Disease Patients Monitored With Treg As A Biomarker

Background:Chronic graft-versus-host disease (cGvHD) is a major complication after allogeneic hematopoietic cell transplantation. Extracorporeal photopheresis (ECP) is an immunotherapy treatment for cGvHD, although suitable response biomarkers are lacking.Materials & methods:We analyzed data from six cGvHD patients undergoing ECP at a reference center from 826 to 2866 days. Circulating Tregs were enumerated, patient's clinical evolution, immunosuppression dose and adverse events (AEs) registered.Results:We observed an increase in Tregs, a decrease in immunosuppression dosage and symptoms improvement. Mild AEs occurred at a very low rate.Conclusion:In these patients, the improvement of cGvHD, with low AEs, confirms a place for ECP as treatment. Improvements were accompanied by an increase in circulating Tregs, suggesting their role as a biomarker.Lay abstract Hematopoietic stem cell transplant is a lifesaving treatment, involving collecting blood-forming cells from a healthy donor and infusing them into a patient. Donor immune cells may attack patient tissues causing severe complications, including death (graft-versus-host disease [GvHD]). Primary treatment for GvHD are steroids. Extracorporeal photopheresis (ECP) is an alternative treatment that induces immunological tolerance, in part, due to Treg. We studied both clinical response and circulating Treg in six patients treated with ECP for up to 8 years. ECP responding patients had less GvHD, reduced the dose of steroids and increased the number of Treg.