Erythroblast predominance without CD41/cyCD41-positive blasts predicts favorable prognosis in patients with myelodysplastic syndromes and acute myeloid leukemias treated with azacitidine.

This study examined the prognostic impact of erythroblast predominance (EP) in 61 patients with myelodysplastic syndromes (MDS) (n = 51) or acute myeloid leukemia (n = 10) treated with azacitidine. Median age was 78 years. EP, defined as > 40% erythroblasts and M/E < 1.0, was found in 21 patients, including 9 complex karyotypes (CK). In the 24 CK of the entire cohort, 5 were hyperdiploid and 15 were monosomal karyotype with -5/5q-, and 10 had immunophenotypically CD41/cyCD41 positive blasts (cyCD41+). The complete response (CR) rate was 32.8%. Median follow-up was 14 months, and median overall survival (OS) was 17 months. Although all patients with EP achieved high CR rates (61.9%) and extended OS (28 M, P = 0.056), patients with EP and cyCD41+ blasts had shorter OS (8 M, P = 0.002). EP (HR 0.39, P = 0.009) and cyCD41+ (HR 3.49, P = 0.018) were identified as prognostic factors in multivariate analysis. All patients with cyCD41+ had hyperdiploid or CK with -5/5q-. In conclusion, we divided patients into three risk categories: high (cyCD41+), low (EP without cyCD41+), and intermediate (non-CD41+ and non-EP), and median OS in these categories was 34, 17 and 8 months, respectively (P < 0.001).