In the AZA-001 trial, azacitidine (75 mg/m(2) /d subcutaneously for Days 1-7 of every 28-day cycle) demonstrated improved survival compared with conventional care regimens in patients with International Prognostic Scoring System-defined intermediate-2- or high-risk myelodysplastic syndrome and World Health Organization-defined acute myeloid leukemia with 20% to 30% bone marrow blasts.

This secondary analysis of the AZA-001 phase 3 study evaluated the time to first response and the potential benefit of continued azacitidine treatment beyond first response in responders.

Overall, 91 of 179 patients achieved a response to azacitidine; responding patients received a median of 14 treatment cycles (range, 2-30). Median time to first response was 2 cycles (range, 1-16). Although 91% of first responses occurred by 6 cycles, continued azacitidine improved response category in 48% of patients. Best response was achieved by 92% of responders by 12 cycles. Median time from first response to best response was 3.5 cycles (95% confidence interval [CI], 3.0-6.0) in 30 patients who ultimately achieved a complete response, and 3.0 cycles (95% CI, 1.0-3.0) in 21 patients who achieved a partial response.

Continued azacitidine therapy in responders was associated with a quantitative increase in response to a higher response category in 48% of patients, and therefore may enhance clinical benefit in patients with higher-risk MDS.