Prognostic impact of c-KIT mutations in core binding factor leukemias. an Italian retrospective study

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 CBFL patients were analysed to ascertain the c-KIT mutation status. In AML with t(8;21), the presence of c-KIT TKD mutation at codon 816 (TKD(816)) was associated with a high white blood cell count at diagnosis (median 29.60x10(9)/L) and a higher incidence (33%) of extramedullary leukaemia (EML) during the course of the disease. Data also showed that the TKD(816) mutation 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 = 0.002; 25% vs 76.5%, p = 0.006, respectively). No difference in relapse incidence (p = 0.126) and OS (p = 0.474) was observed between the c-KIT mutated other than TKD(816) (n = 7) and the c-KIT- patients. These findings indicate that c-KIT TKD816 mutation has a negative impact on the outcome of AML with t(8;21).