Incidence and prognostic impact of c-Kit , FLT3 , and Ras gene mutations in core binding factor acute myeloid leukemia (CBF-AML)

In core binding factors (CBF) acute myeloid leukemia (AML), the disruption of CBFalpha/beta genes impairs normal hematopoietic differentiation and is supposed to cooperate with additional mutations promoting proliferation. The incidence and the prognosis of receptor tyrosine kinase (RTK) c-Kit and FLT3 mutations and Ras mutations were evaluated in 103 pediatric and adult patients with CBF-AML. c-Kit mutations were present in 17% patients. c-Kit exon 8 mutations were more frequent in inv(16) than in t(8;21) subset (20 versus 6%). Only one patient had FLT3-ITD but FLT3-D835 was as frequent as reported in AML population (7%). Ras mutations were significantly more frequent in inv(16) than in t(8;21) subset (36 versus 8%, P=0.001). RTK mutations were associated with a higher white blood cell count (WBC) (36 versus 21 G/L, P=0.05). FLT3 mutations were significantly associated with a shorter EFS and survival (P<0.0001 and P=0.0002) owing to an excess of early events. c-Kit mutations were associated with a shorter EFS and RFS (P=0.002 and P=0.003) in t(8;21) but not inv(16) patients. As previously observed, Ras mutations did not affect prognosis. Screening for RTK mutations may help to identify patients with a more adverse outcome and thus susceptible to benefit from intensified protocols or RTK inhibitors.