Despite progress in the understanding of leukemia pathophysiology, the treatment of acute myeloid leukemia (AML) remains challenging. In patients with refractory or relapsed (R/R) AML, the prognosis is still poor and this group is targeted for new drug development. We reviewed the outcome of 47 patients, with R/R AML after at least one course of intensive chemotherapy, treated with 5-azacytidine in three different French institutions. The overall response rate was 38% including complete remission in 21%, partial remission in 11%, and hematological improvement in 6% of cases. Median time to relapse was 6 (range, 1-39) months. Median overall survival was 9 months (not reached by responders vs. 4.5 months for nonresponders patients, P = 0.0001). Univariate analysis identified the absence of peripheral blood blasts and <20% bone marrow blasts as prognostic factors for both overall response and survival, but not age, ECOG/PS, type of AML, cytogenetic, status of the disease, number of previous lines of therapy, previous hematological stem cell transplantation, or white blood cells count. Bone marrow blasts percentage <20% was the only independent prognostic factor identified by multivariate analysis for overall response (P = 0.0013) and survival (P = 0.0324). Six patients in remission could proceed to an allogenic hematological stem cell transplantation. The drug-related grade 3/4 adverse events were hematopoietic toxicities (38%) and infection (32%). In conclusion, this study suggests that a salvage therapy with 5-azacytidine is an interesting option for patients with R/R AML after intensive chemotherapy. Prospective randomized studies are needed to demonstrate a superiority of this approach over others strategies.
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