Safety and collection efficiency with a lower transfusion threshold for extracorporeal photopheresis in adult patients with graft-versus-host disease.

Background Extracorporeal photopheresis (ECP) is an established treatment for graft-versus-host disease (GVHD). Various haematocrit thresholds have been used to trigger red blood cells transfusion prior to ECP. Moderate-to-severe GVHD is frequently complicated by anaemia; the safety and collection efficiency with a lower haematocrit for ECP is unknown. Methods We prospectively enrolled 26 consecutive adult GVHD patients with haematocrits between 25% and 28.9% who received ECP on the CELLEX system. Preprocedural transfusion was withheld. We monitored the adverse events and transfusions avoided. A complete blood cell count with differential was performed on preprocedural peripheral blood and buffy coat collected. Lymphocyte fold enrichment (LFE) was compared between this cohort and two historical control groups with haematocrits of 29% or higher. Results Red Blood Cells transfusion was avoided in the lower-haematocrit cohort without adverse events. The median LFE was 4.5 (95% CI, 3.1-5.7) in the lowerhaematocrit cohort and 5.2 (95% CI, 4.1-6.5) in the higher-haematocrit CELLEX-treated control group. The median difference was 0.7 (95% CI, -0.3 to 2.0, P = 0.14). It could not be established that the lower-haematocrit cohort was non-inferior to the higher-haematocrit control group with a prespecified non-inferiority margin of 1.3. However, LFE was significantly higher in the lower-haematocrit cohort than the higher-haematocrit UVAR XTS-treated control group (P < 0.01). Conclusion Buffy coat can be collected for ECP using CELLEX in GVHD patients with a haematocrit of 25% or higher, with a collection efficiency superior to that in patients with higher haematocrits but treated using UVAR XTS. No increase in adverse events was observed at these lower haematocrits.