T he prognosis of patients with acute myeloid leukemia in whom primary treatment fails remains very poor. In order to improve such patients' outcome, we conducted a phase 2, prospective, multicenter trial to test the feasibility of a new sequential regimen, combining a short course of intensive chemotherapy and a reduced intensity-conditioning regimen, before allogeneic stem-cell transplantation. Twenty-four patients (median age, 47 years) with acute myeloid leukemia in primary treatment failure were included. Cytogenetic risk was poor in 15 patients (62%) and intermediate in nine (38%). The sequential regimen consisted of clofarabine (30 mg/m 2 /day) and cytosine arabinoside (1 g/m 2 /day) for 5 days, followed, after a 3-day rest, by reduced-intensity conditioning and allogeneic stem-cell transplantation combining cyclophosphamide (60 mg/kg), intravenous busulfan (3.2 mg/kg/day) for 2 days and anti-thymocyte globulin (2.5 mg/kg/day) for 2 days. Patients in complete remission at day +120 received prophylactic donor lymphocyte infusion. Eighteen patients (75%) achieved complete remission. With a median follow-up of 24.6 months, the Kaplan-Meier estimate of overall survival was 54% (95% CI: 33-71) at 1 year and 38% (95% CI: 18-46) at 2 years. The Kaplan-Meier estimate of leukemia-free survival was 46% (95% CI: 26-64) at 1 year and 29% (95% CI: 13-48) at 2 years. The cumulative incidence of non-relapse mortality was 8% (95% CI: 1-24) at 1 year and 12% (95% CI: 3-19) at 2 years. Results from this phase 2 prospective multicenter trial endorsed the safety and efficacy of a clofarabine-based sequential reduced-toxicity conditioning regimen, which warrants further investigation. This study was registered at www.clinicaltrials.gov, identifier number: NCT01188174.
IntroductionThe prognosis of patients with acute myeloid leukemia (AML) in primary treatment failure remains very poor. Primary treatment failure or primary refractory AML is defined by failure to achieve a complete hematologic remission (CR) after one or two courses of induction chemotherapy.1,2 For these patients, the chance of achieving a CR with another standard or conventional treatment, including the use of intermediate-or high-dose cytosine arabinoside (Ara-C) alone or in combination with an
ABSTRACT
© Ferrata Storti Foundationanthracycline, fludarabine or gemtuzumab-ozogamicin, is 10-20% at best. The overall survival rate at 1 year is less than 20%, with a median survival of less than 6 months.3-5