Extracorporeal Photopheresis for Steroid-Refractory Graft-Versus-Host Disease in Recipients of T-Cell Deplete Allogeneic Peripheral Blood Stem Cells.

Introduction Graft-versus-host disease (GVHD) is the leading cause of morbidity and mortality following allogeneic hematopoietic stem cell transplant (allo-HSCT). According to different transplant platforms, the overall incidence of acute (aGVHD) and chronic (cGVHD) is between 30-50% and 20-60%, respectively. In both scenarios, first-line therapy consists of systemic corticosteroids and will be effective in only 50% of patients. Second-line treatment with the immunomodulatory effect of extracorporeal photopheresis (ECP) aims to stop tissue damage and induce immune tolerance. Objective Herein, we report the outcome of steroid-refractory GVHD (SR-GVHD) patients treated with ECP at King's College Hospital, London, between May 2015 and May 2023 Methods Eligible patients were identified in the GVHD database established in 2019. This tool is a prospective data collection following a weekly GVHD-focused evaluation of the transplant patients admitted at our institution for any medical reason.Between September 2019 and May 2023, 798 GVHD evaluations were performed on 250 transplant patients. 60 SR-GVHD patients were treated with ECP and eligible for this analysis. All the patients underwent allo-HSCT with peripheral blood stem cells (PBSC). SR-GVHD was diagnosed according to EBMT and NIH guidelines for aGVHD and cGVHD, respectively. ECP was administered with a closed circle (Therakos) twice weekly for the first 4-6 weeks, then tapered according to response criteria. Probabilities of overall survival (OS) and failure-free survival (FFS) were calculated using the Kaplan-Meier method. Statistical analyses were performed with GraphPad Prism Version 10.0.2. Results Table 1 summarizes the demographic of the population and allo-HSCT details.Acute and chronic SR-GVHD was diagnosed in 15 and 46 patients, respectively.Median time to onset of acute and chronic GVHD was 57 days (range 32-94) and 195 days (range 100-1364) post allo-HSCT, respectively. Median time to initiation of ECP was 39 days (range 2 – 426). Overall response rate was 55% in both acute and chronic GVHD patients. Median OS and FFS from the initiation of ECP were 32 and 22 months, respectively (figure 1A and 1B). Median OS for acute and chronic GVHD was 8 months and not reached, respectively (fig. 1C). Within the cGVHD cohort, median OS for moderate and severe cases was not reached and 48 months, respectively (fig 1D). The main causes of death were infections (18%), relapsed disease (13%) and refractory GVHD (11%). Conclusion ECP is an effective rescue strategy in SR-GVHD following t-deplete PBSC allo-HSCT.The use of ECP in the treatment of SR GvHD results in improved overall survival secondary to lower relapse rates and infective death and better GVHD control.