The 46th Annual Meeting of the European Society for Blood and Marrow Transplantation, 29 August - 01 September 2020, pp.656-657
Background: Some of the studies suggest that in highly sensitized patients who have antibodies against human leukocyte antigens (HLA) before allogeneic hematopoietic stem cell transplantation (AHSCT), primary graft failure risk increases. These HLA antibodies which are called as panel-reactive antibody (PRA) may be caused because of previous blood transfusions or AHSCT. In this study, we aimed to determine the association of PRA with engraftment, chimerism and graft versus host disease (GVHD) in pediatric hematopoietic stem cell transplant patients.
Methods: In this study, 43 patients who had PRA positivity and went to AHSCT between October 2014 and November 2019 are investigated retrospectively. Fourtytwo patients who were matched for diseases and PRA negative were taken as control group. Class I and Class II PRAs directed to HLA antigens were detected by Luminex System. In PRA-positive group, three types of treatment modalities were used. Methylprednisolone was administered at a dose of 0.5 mg/kg/day for 28 days starting from day -1. Rituximab was given at a dose of 375 mg/m2/day, at day -1. Plasmapheresis (PP) was performed two times, before conditioning regimen and at day -1. Both groups were compared in terms of graft failure, chimerism and GVHD.
Results: Median age of patients was 89.7 in months. Fourty-three (50.6%) of them were female. Both of the groups were homogenous in terms of diagnosis, donor type, HLA match, stem cells source and ABO mismatch. The most frequent diagnosis was hemoglobinopathies (n=:36, 42.3%). In PRA-positive group, PRA Class I, II or both were detected in 14 (32.5%), 11 (25.5%) or 18 (42%) patients, respectively. Median value of PRA Class I±SD was 51.5±33.9% and PRA Class II±SD was 46±28.8%. Thirty-eight patients received at least one of treatment modalities. Treatment strategy was decided according to the patient’s underlying disease, donor type, level of PRA positivity and PRA class. Eighteen patients received only methylprednisolone, 3 patients received only rituximab, 2 patients underwent PP, 5 patients received methylprednisolone plus rituximab, 7 patients underwent PP plus methylprednisolone and 3 patients received all of three treatment modalities. Five patients who had low titer of PRA in Class II didn’t take any treatment. Poor graft function occurred in 6 (13.9%) patients in PRA-positive group and 5 (11.9%) patients in control group. There was no statistically significant difference in both groups in terms of myeloid engraftment, thrombocyte engraftment, chimerism, acute GVHD and viral infection frequency. The 100-day overall survival (OS) was 96.7% for the PRA-positive group and 90.4% for control group (p>0.05). The 1-year OS was 85% for the PRA-positive group and 83% for the PRA-negative group (p>0.05). The 5-year OS was 66% and 83% for PRA-positive and negative groups, respectively (p>0.05).
Conclusions: In conclusion, our experience suggests that
PRA positivity does not influence the engraftment and
survival. Further more comprehensive studies aimed at the
influence of PRA on AHSCT in pediatric patients are