[Outcome of haploidentical hematopoietic stem cell transplantation for refractory/relapsed acute leukemia]

To explore the outcome of human leukocyte antigen (HLA)-mismatched/haploidentical hematopoietic stem cell transplantation (HSCT) for refractory/relapsed acute leukemia (AL) patients and its related risk factors.

96 refractory/relapsed AL patients who received HLA-mismatched/haploidentical HSCT following conditioning regimen comprised of modified busulfan/cyclophosphamide (BU/CY) plus thymoglobulin (ATG) from Jan 2003 to Jun 2011 were analyzed retrospectively.

Of the 96 patients, 61 suffered from acute myeloid leukemia (AML), and 35 acute lymphoid leukemia (ALL), all of them in non-remission (NR) or relapse before transplantation. With a median follow-up of 373 (34 - 3157) d, 33 cases (34%) survived, 31 survived without leukemia, and 35 relapsed. The estimated 3-year overall survival (OS) and disease-free survival (DFS) rate was 30.2% and 29.0%, respectively. The 3-year OS rate was significantly higher for AML patients (39.2%) than for ALL patients (15.4%) (P = 0.005). The estimated 3-year OS probabilities for patients with and without prophylactic donor lymphocyte infusion (DLI) were 38.0% and 11.8%, respectively (P = 0.001). Sex, age, conditioning regimen (BU/CY or not, dosage of ATG), the number of HLA mismatches between the donor and recipient, and the number of infused mononuclear cells were not independent factors affecting OS, DFS and relapse. Multivariate analysis showed that DFS rate was significantly higher in patients receiving prophylactic DLI (P = 0.003), in patients with AML (vs with ALL) (P = 0.037) and with chronic GVHD (P = 0.006).

Haploidentical HSCT may prolong DFS in part refractory/relapsed AL patients and even cure them. Prophylactic DLI may reduce relapse and increase survival; for patients with refractory/relapsed ALL, other therapy for prevention and treatment of post-transplant relapse should be explored.