Abstract

Background: Indications for allogeneic hematopoietic stem cell transplantation (allo-HCT) with reduced-intensity conditioning (RIC) have expanded widely for elderly patients and those with comorbidities. However, the optimal RIC regimen remains uncertain. A combination of fludarabine phosphate (Flu) and melphalan (Mel) is widely used in RIC regimen with comparable results to that of fludarabine phosphate and busulfan. In our hospital, Flu/Mel and low-dose total body irradiation (Flu/Mel/TBI) is mainly used in RIC regimen. We analyzed safety and efficacy in allo-HCT patients with Flu/Mel/TBI.

Methods: This study was a retrospective analysis of patients with hematopoietic malignancies who received their first allo-HCT with Flu/Mel/TBI from between January 2005 to December 2015. Patients were included for Flu/Mel/TBI treatment for elderly, those with a recent fungal infection or organ dysfunction. Flu/Mel/TBI consists of intravenous Flu (125-150 mg/m2), Mel (140 mg/m2), and TBI (2-4 Gy). GVHD prophylaxis consists of tacrolimus and short-term methotrexate with or without low-dose anti-thymocyte globulin (ATG). The primary end point was non-relapse mortality (NRM) on day 100. As the secondary end point, we verified the effects about Flu/Mel/TBI for patients with non-remission.

Results: From January 2005 to December 2015, 168 patients received conditioning regimens with Flu/Mel/TBI. The median age was 59 years (16-71 years). Hematopoietic malignancies consisted of acute myeloid leukemia (AML) (n=74), myelodysplastic syndrome (MDS) (n=63), acute lymphoblastic leukemia (ALL) (n=12), malignant lymphoma (ML) (n=10), chronic myeloid leukemia (CML) (n=5), adult T-cell leukemia (ATL) (n=2), acute myeloid/NK cell leukemia (n=1), and chronic active Epstein-Barr virus infection (CAEBV) (n=1). Twenty-eight donors were HLA matched siblings, 6 were mismatched siblings, and 2 were haplo-identical donors. Of these, 55 had matched unrelated bone marrow donors, and 47 had 1-allele mismatched unrelated donors and 30 cord blood donors. With regard to disease status at allo-HCT, 44 patients (26.0%) were in remission and 124 patients (74.0%) were non-remission. Forty-nine patients were administered low-dose ATG. The median observation period of survivors was 2021 days (758-4660 days). Neutrophil engraftment was achieved in 89.3%. Median neutrophil recovery to over 500/µl was obtained on day 19 (11-87). Cumulative incidence of NRM at day 100 was 17.4%. Early death, defined as death before day 100, from allo-HCT occurred in 32 patients. Three patients had early relapse. Causes for NRM were infection in 15 patients (8 pneumonia, 7 sepsis), acute cardiac failure in 3 patients, cerebral hemorrhage in 2 patients, thrombotic microangiopathy in 2 patients, acute GVHD in 1 patient, hemophagocytic syndrome in 1 patient, and 5 other causes. NRM rates at day 100 by disease status at allo-HCT showed no significant differences (remission: 15.9% vs non-remission: 17.9%, p=0.15). Overall survival (OS) and disease-free survival (DFS) at 2 years were 50.6% and 43.5%, respectively. Survival rates with regard to disease status showed significant differences. Patients in remission had a 2-year OS of 65.9%, whereas patients in non-remission had a 2-year OS of 45.2% (p=0.031). Patients in remission had a 2-year DFS of 59.1%, whereas patients in non-remission had a 2-year DFS of 37.9% (p=0.016). Cumulative incidences of grade 2-4 and 3-4 acute GVHD were 30.7% and 17.1%, respectively. Cumulative incidence of relapse at 2 years was 29.8%.

Conclusion: The current study proved that disease status at allo-HCT were mainly in non-remission. In such a situation, RIC using Flu/Mel/TBI was well tolerated with relatively low NRM, and was sufficient to allow engraftment for elderly or frail patients with hematopoietic malignancies.

Disclosures

No relevant conflicts of interest to declare.

Author notes

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