Low dose 5-azacytidine is ineffective for remission induction in patients with acute myeloid leukemia

Low dose 5-azacytidine was administered to 11 patients with acute myeloid leukemia (AML) in hopes of achieving complete remissions by inducing differentiation of leukemic blasts. The patient population included both patients who had received no prior therapy (two patients), as well as patients refractory to primary therapy (five patients) and patients who had relapsed after achieving complete remission (four patients). Both previously untreated patients had a history of myelodysplastic syndrome, and two of the primarily refractory patients had leukemia following chemotherapy for other malignancies. The median age was 55 years (range 36-78 years). Twenty-one courses of 5-azacytidine were administered as 7-day continuous infusions at a dose of 75 mg/m2/day. Significant nonhematologic toxicity was not observed. No patient had a response as defined by bone marrow remission or improvement in transfusion requirement for red blood cells or platelets. Although some patients developed bone marrow hypocellularity (six courses in five patients), none became aplastic, and eight courses in six patients were associated with increased bone marrow cellularity percentage of blasts. Five courses in three patients were inevaluable (one central nervous system hemorrhage, one central nervous system leukemia, three courses in one patient who refused bone marrow aspiration). It is unlikely that low dose 5-azacytidine will be of benefit to patients with AML, and there was no evidence of clinically significant induction of differentiation noted.