Distinct forms of tyrosine kinase domain (TKD), juxtamembrane domain, exon 8, and internal tandem duplication (ITD) mutations of c-KIT, were observed in about 46% of core binding factor leukemia (CBFL) patients. To evaluate their prognostic significance, 67 adult patients with CBFL were analyzed to ascertain the c-KIT mutation status. In acute myeloid leukemia (AML) with t(8;21), the presence of c-KIT TKD mutation at codon 816 (TKD816) was associated with a high white blood cell count at diagnosis (median, 29.60 × 10 9/L) and a higher incidence (33%) of extramedullary leukemia (EML) during the course of the disease. Data also showed that the TKD816 mutated patients (n = 12) had a significantly higher incidence of relapse and a lower overall survival (OS) at 24 months, compared with the 17 c-KIT unmutated (c-KIT-) patients (90% vs 35.3%, P = .002; 25% vs 76.5%, P = .006, respectively). No difference in relapse incidence (P = .126) and OS (P = .474) was observed between the c-KIT mutated other than TKD816 (n = 7) and the c-KIT- patients. These findings indicate that c-KIT TKD 816 mutation has a negative impact on the outcome of AML with t(8;21).
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