Allogeneic stem cell transplantation after fludarabine, melphalan and thymoglobulin followed by early withdrawal of prophylactic immunosuppression in patients with acute lymphoblastic leukemia – update of single center study

Presented are updated results of allogeneic hematopoietic stem cell transplantations (HSCTs) in 25 adult patients with acute lymphoblastic leukemia (ALL) in complete remission (CR) after a reduced intensity conditioning (RIC) combining fludarabine (150 mg/m2) and melphalan (140 mg/m2) with thymoglobulin (4.5 mg/kg or recently 4.0 mg/kg) followed by early initiation of reduction and withdrawal of prophylactic posttransplant immunosuppression. The median post-transplant follow-up was 32 (range, 4-87) months. Stable engraftment of donor's hematopoiesis was achieved in all patients. Acute graft versus host disease (GVHD) as well as the chronic one were equally observed in four cases (16%). Five patients (20%) relapsed with ALL in the median of 9 (range, 3-15) months after HSCT. During the above post-transplant follow-up, 4 recipients (16%) died. Disease progression and posttransplant complications were the cause of death in three (12%) and one (4%) of them, respectively. The probabilities of 2-year event-free (EFS) and overall survival (OS) were 70.3% (95% CI 51.9-88.7%) and 86.1% (95% CI 71.6-100%), respectively. Presented study confirmed our previously reported promising results and this approach may be considered as an alternative to traditional HSCTs performed in high-risk patients with ALL.