The CALGB conducted a series of clinical trials with azacitidine (Vidaza®) administered subcutaneously or intravenously in patients with MDS using the FAB classification (

JCO 2002;20:2429
). Since completion of these CALGB studies (8421, 8921, 9221), a new classification system was developed by the WHO that distinguishes MDS from AML (blasts > 20%). Although studies with azacitidine in patients with AML had previously shown activity, the 75 mg/m2/day dose in the CALGB studies was lower than previously studied. Using the WHO system, the diagnosis for CALGB study patients was redefined and patients with AML were analyzed separately. Most of the 105 patients were previously considered refractory anemia with excess blasts in transformation (RAEB-T). Also, new treatment response criteria for MDS were published by the IWG (
Blood 2000; 96:3671
). Using IWG response criteria, azacitidine patients with WHO AML in studies 8421, 8921, or 9221 had an overall response rate (CR+PR+HI) of 48% (12/25), 32% (9/28), and 37% (10/27), respectively.

Best Response using IWG Response Criteria for WHO AML Patients in Studies 8421, 8921, and 9221

Best Response using IWG Response Criteria for WHO AML Patients in Studies 8421, 8921, and 9221
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Best Response using IWG Response Criteria for WHO AML Patients in Studies 8421, 8921, and 9221
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Median duration of any response (CR, PR or HI) in the 33 azacitidine-treated responders was 279 days (range: 61 to 724 days). The median duration of CR in the 8 azacitidine-treated responders was not achieved; however, the 25th percentile was 115 days (range: 92 to 274+ days). In Study 9221, the median duration of transfusion independence (defined as ≥56 days) in patients independent at baseline was significantly longer in the azacitidine group compared with supportive care for red blood cells (azacitidine [n=8]: 411 days vs. supportive care [n=9]: 133 days, p=0.02) and platelets (azacitidine [n=13]: 363 days vs. supportive care [n=18]: 125 days, p=0.004). In the azacitidine group, 22% (6/27) of patients had a hemoglobin improvement to >11 g/dL that was maintained for ≥56 days compared with 8% (2/25) in the supportive care group (p=0.2). The proportions of patients with ANC >1500/m3 and platelets >100,000/mm3 lasting for ≥56 days were similar between the treatment arms. Azacitidine patients with WHO AML had a longer median survival (19.3 months) compared with the supportive care group (12.9 months) (p=0.2). Further studies investigating azacitidine in patients with AML with dysplasia are warranted.

Topics:
azacitidine, frequency of responses, leukemia, myelocytic, acute, myelodysplastic syndrome, world health organization, supportive care, refractory anemia with excess blasts, dysplasia, hemoglobin, transfusion

Author notes

Corresponding author

2005, The American Society of Hematology
2005
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