Objective: Immunosuppression intensified conditioning regimen has been applied for 10 patients with strong positive pre-transplantation Donor specific Anti-HLA Antibodies (DSAs) undergoing Haploidentical Hematopoietic Stem Cell Transplantation (HSCT), its effects on engraftment of hematopoietic stem cell were examined.

Methods: Characteristics of 10 consecutive patients with strong positive pre-transplantation DSAs were retrospectively analyzed, including gender, age, diagnosis, disease status pre-transplantation, presence of DSA, conditioning regimens, engraftment, graft versus host disease (GVHD) incidence and survival.

Results: Ten patients [3 males vs 7 females, median age 53.5(36-64)] received immunosuppression intensified conditioning regimen: Fludarabine plus busulfan (FluBu) combining total body irradiation and cyclophosphamide (TBI-Cy). DSA levels gradually decreased in all patients after preparative conditioning, and the mean fluorescence intensity (MFI) values dropped significantly (P＜0.003). The average MFI values dropped 40% at day 7 post-HSCT, 8 cases acquired hematopoietic reconstitution, the median time of neutrophil engraftment was 15.6(10-16) days, and 19(13-22) days for platelet engraftment. One case had primary graft failure and another one had poor graft function. After a median follow-up of 12.5(1.5-27) months, 7 cases remained in disease remission state with negative DSA assay, including 2 cases with MFI values higher than 20000 pre-transplantation.

Conclusions：Immunosuppression intensified conditioning regimen can efficiently decrease the Donor specific Anti-HLA Antibodies (DSA) level, which leads to lowered chances of primary graft failure.

No relevant conflicts of interest to declare.

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2023
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