CloFluBu-conditioning results in encouraging EFS for ALL and AML, with low TRM, limited incidence of aGvHD and GF, and no cases of VOD.
Minimal residual disease status prior to transplantation impacted outcome due to increased relapse risk in both AML and ALL patients
We prospectively studied 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 anti-leukemic activity. All patients receiving their first HCT, from 2011-2019, were included and received CloFluBu. 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, and veno-occlusive disease (VOD). Cox Proportional Hazard- and Fine and Gray competing-risk models were used for data analysis. 155 Children were included; 60 acute lymphoid leukemia (ALL), 69 acute myeloid leukemia (AML), and 26 other malignancies (mostly MDS-EB). Median age was 9.7 (0.5-18.6) years. Estimated 2-yr EFS was 72.0% ± 6.0 in ALL, and 62.4% ± 6.0 in AML patients. TRM in the whole cohort was 11.0% ± 2.6, incidence of aGvHD III-IV at 6 months was 12.3% ± 2.7, extensive chronic GvHD at 2-yr 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.