The Addition of Extracorporeal Photophoresis (ECP) to Tacrolimus and Methotrexate to Prevent Acute and Chronic Graft-Versus Host Disease (aGvHD, cGvHD) in Patients Undergoing a Myeloablative (MA) Hematopoietic Cell Transplant (HCT)

Acute and chronic GvHD occurs in 50-70% of patients undergoing HCT despite GvHD prophylaxis. In this study, ECP was added as GvHD prophylaxis for 10 treatments, 2 treatments prior to the start of the conditioning regimen and 8 after engraftment at two treatments every two weeks. All pts also received tacrolimus and methotrexate and 8 also received ATG. 20 pts (13 males, ages 28 – 57) were enrolled. All pts underwent a MA HCT (15 Bu-Cy and 5 Cy-TBI), 11 from matched unrelated, 5 from related and 4 from mismatched unrelated donors. 15 had AML or MDS and 5 ALL or NHL. 4 pts died before day 100 (RSV n=1, GvHD and sepsis n=1 and relapse n=2). 12 pts received all the 10 planned ECP treatments while 8 received 2-6 of the treatments due to death before day 100 (n=4), relapse (n=2), and withdrawal due to iv access issues (n=2).  4 patients required blood products before ECP. AGvHD grade 2 – 4 occurred in 12 of 19 (63%) evaluable pts while grade 3-4 occurred in 4 (21%).  4 of 14 surviving pts developed chronic GvHD (28%), 3 extensive and 1 limited. Two pts died from cGvHD. 14 patients (70%) are alive from 5 months to 30 months post HPCT.  PBMCs were collected before ECP therapy and three months post-HPCT.  T cells were analyzed for CD45RO, B cells for IgD, and CD4⁺ T cells for FoxP3.  In patients who developed GvHD, fewer T cells expressed CD45RO, but more B cells had isotype class-switched.  Patients who did not develop GvHD had more Treg cells (fig).  These data indicate ECP may be effective as prophylactic therapy for cGvHD and should be further investigated.  The pre-transplant lymphocyte phenotype might predict post-transplant lymphocyte activity and the efficacy of ECP as a prophylactic therapy.