Adults with HR, Ph-negative ALL and good MRD clearance after induction and early consolidation show promising outcome without allo-HSCT.
Early assignment to allo-HSCT might provide a long-term response to a fraction of patients showing a suboptimal response to Induction-1.
The need for allogeneic hematopoietic stem cell transplantation (allo-HSCT) in adults with Philadelphia chromosome-negative (Ph-neg) acute lymphoblastic leukemia (ALL) with high-risk (HR) features and adequate measurable residual disease (MRD) clearance remains unclear. The aim of the ALL-HR-11 trial was to evaluate the outcomes of HR Ph-neg adult ALL patients following chemotherapy or allo-HSCT administered based on end-induction and consolidation MRD levels. Patients aged 15-60 years (y) with HR-ALL in complete response (CR) and MRD levels (centrally assessed by 8-color flow cytometry) <0.1% after induction and <0.01% after early consolidation, were assigned to receive delayed consolidation and maintenance therapy up to 2y in CR. The remaining patients were allocated to allo-HSCT. CR was attained in 315/348 patients (91%), with MRD <0.1% after induction in 220/289 patients (76%). By intention-to treat, 218 patients were assigned to chemotherapy and 106 to allo-HSCT. The 5-year (±95%CI) cumulative incidence of relapse (CIR), overall survival (OS) and event-free survival (EFS) probabilities for the whole series were 43%±7%, 49%±7% and 40±6%, respectively, with CIR and OS rates of 45±8% and 59±9% for patients assigned to chemotherapy and of 40±12% and 38±11% for those assigned to allo-HSCT, respectively. Our results show that avoiding allo-HSCT does not hamper the outcomes of HR Ph-neg adult ALL patients up to 60y with adequate MRD response after induction and consolidation. Better post-remission alternative therapies are especially needed for patients with poor MRD clearance. ClinicalTrials.gov (NCT01540812)