Comparison of 7-day azacitidine and 5-day decitabine for treating myelodysplastic syndrome

Two DNA methyltransferase inhibitors, azacitidine and decitabine, are currently approved for the treatment of myelodysplastic syndrome (MDS). Choosing between these drugs is an important practical issue. In this retrospective study, patients receiving AZA-7d (azacitidine 75 mg/m2 subcutaneously × 7 days, n = 75) or DEC-5d (decitabine 20 mg/m2 intravenously × 5 days, n = 74) were compared. The rates of hematologic response (complete response [CR]/partial response [PR]/marrow CR) were 12.0 % (AZA-7d) vs. 29.7 % (DEC-5d) (P = 0.008), and the overall response rates (CR/PR/marrow CR/hematologic improvement) were 52.0 % (AZA-7d) vs. 63.5 % (DEC-5d) (P = 0.155). Grade 3 or higher neutropenia occurred more frequently with DEC-5d (79.6 %) than with AZA-7d (72.2 %) (P = 0.040). Overall survival probabilities at 2 years were 42.1 % (AZA-7d) vs. 42.2 % (DEC-5d) (P = 0.944). Subgroup analysis revealed that AZA-7d associated with higher survival rates than DEC-5d in patients whose MDS duration exceeded 1 year or who had poor performance status. In conclusion, both AZA-7d and DEC-5d regimens were effective in treating patients with MDS. However, the two regimens differed in terms of clinical responses and toxicities. One hypomethylating regimen may be superior to the other regimen in particular subgroups.