Clofarabine-fludarabine-busulfan in HCT for pediatric leukemia: an effective, low toxicity, TBI-free conditioning regimen

Blood Adv. 2022 Mar 22;6(6):1719-1730. doi: 10.1182/bloodadvances.2021005224.

Abstract

We prospectively studied clofarabine-fludarabine-busulfan (CloFluBu)-conditioning in allogeneic hematopoietic cell therapy (HCT) for lymphoid and myeloid malignancies and hypothesized that CloFluBu provides a less toxic alternative to conventional conditioning regimens, with adequate antileukemic activity. All patients receiving their first HCT, from 2011-2019, were included and received CloFluBu. The primary endpoint was event-free survival (EFS). Secondary endpoints were overall survival (OS), graft-versus-host disease (GvHD)-relapse-free survival (GRFS), treatment-related mortality (TRM), cumulative incidence of relapse (CIR), acute and chronic GvHD (aGvHD and cGvHD), and veno-occlusive disease (VOD). Cox proportional hazard and Fine and Gray competing-risk models were used for data analysis. One hundred fifty-five children were included: 60 acute lymphoid leukemia (ALL), 69 acute myeloid leukemia (AML), and 26 other malignancies (mostly MDS-EB). The median age was 9.7 (0.5 to 18.6) years. Estimated 2-year EFS was 72.0% ± 6.0 in ALL patients, and 62.4% ± 6.0 in AML patients. TRM in the whole cohort was 11.0% ± 2.6, incidence of aGvHD 3 to 4 at 6 months was 12.3% ± 2.7, extensive cGvHD at 2 years was 6.4% ± 2.1. Minimal residual disease-positivity prior to HCT was associated with higher CIR, both in ALL and AML. CloFluBu showed limited toxicity and encouraging EFS. CloFluBu is a potentially less toxic alternative to conventional conditioning regimens. Randomized prospective studies are needed.

MeSH terms

  • Busulfan / adverse effects
  • Child
  • Clofarabine
  • Graft vs Host Disease* / pathology
  • Hematopoietic Stem Cell Transplantation*
  • Humans
  • Leukemia, Myeloid, Acute* / drug therapy
  • Recurrence
  • Vidarabine / analogs & derivatives

Substances

  • Clofarabine
  • Vidarabine
  • Busulfan
  • fludarabine