In the AZA‐001 trial, azacitidine (75 mg/m²/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. Cancer 2011. © 2011 American Cancer Society.