Comparison of cladribine- and fludarabine-based induction chemotherapy in relapsed or refractory acute myeloid leukaemia

Induction regimens integrating cladribine or fludarabine have shown promising outcomes in relapsed or refractory (R/R) acute myeloid leukaemia (AML). We compared the outcome of a cladribine-versus a fludarabine-based regimen as induction chemotherapy for R/R-AML. We included patients with R/R-AML who were treated with a cladribine-or fludarabine-based chemotherapy between 2006 and 2015. We analysed 120 patients, 65 treated with cladribine and 55 treated with fludarabine. The CR rates were 62.7 and 61.4 % for the cladribine group and fludarabine group, respectively (p = 0.890). Poor prognostic factors included older age, secondary AML, poor cytogenetic risk group, prior induction failure, and short first CR duration. No significant overall survival (OS) or relapse-free survival (RFS) differences were found between the groups (OS, p = 0.213; RFS, p = 0.143). However, in a certain subset, survival outcomes were better with cladribine than with fludarabine, including de novo AML, CR at first induction therapy, and not-poor cytogenetic risk group inclusion without overt chemotherapy-refractoriness. By contrast, secondary AML patients had improved survival outcomes when treated with the fludarabine regimen. After CR, better outcomes were observed when allogeneic stem cell transplantation (SCT) was given as consolidation. In R/R-AML, cladribine-and fludarabine-based combination induction chemotherapy had differential survival outcomes according to disease characteristics. Allogeneic SCT after CR with a purine analogue-based regimen improved long-term outcome in these patients.