Exome sequencing identifies recurring FLT3 N676K mutations in core-binding factor leukemia

Sabrina Opatz, Harald Polzer, Tobias Herold, Nikola P. Konstandin, Bianka Ksienzyk, Evelyn Zellmeier, Sebastian Vosberg, Alexander Graf, Stefan Krebs, Helmut Blum, Karl Peter Hopfner, Purvi M. Kakadia, Stephanie Schneider, Annika Dufour, Jan Braess, Maria Cristina Sauerland, Wolfgang E. Berdel, Thomas Büchner, Bernhard J. Woermann, Wolfgang Hiddemann, Karsten Spiekermann, Stefan K. Bohlander, Philipp A. Greif

Key points

  • FLT3 N676K mutations without concurrent internal tandem duplication (ITD) are associated with core-binding factor leukemia

  • N676K activates FLT3 and downstream signaling pathways


The t(8;21) and inv(16)/t(16;16) rearrangements affecting the core-binding factors, RUNX1 and CBFB, respectively, are found in 15-20% of adult de novo AML cases and are associated with a favourable prognosis. Since the expression of the fusion genes CBFB/MYH11 or RUNX1/RUNX1T1 alone is not sufficient to cause leukemia, we performed exome sequencing of an AML sample with an inv(16) to identify mutations, which may collaborate with the CBFB/MYH11 fusion during leukemogenesis. We discovered an N676K mutation in the ATP-binding domain (TKD1) of the fms-related tyrosine kinase 3 (FLT3) gene. In a cohort of 84 de novo AML patients with a CBFB/MYH11 rearrangement and in 36 patients with a RUNX1/RUNX1T1 rearrangement, the FLT3 N676K mutation was identified in 5 and 1 patients, respectively (5/84, 6%; 1/36, 3%). The FLT3-N676K mutant alone leads to factor-independent growth in Ba/F3 cells and, together with a concurrent FLT3-ITD, confers resistance to the FLT3 PTK inhibitors PKC412 and AC220. Gene expression analysis of AML patients with CBFB/MYH11 rearrangement and FLT3 N676K mutation showed a trend towards a specific expression profile. Ours is the first report of recurring FLT3 N676 mutations in CBF leukemias and suggests a defined subgroup of CBF leukemias. Registered at AMLCG-1999 trial (NCT00266136)

  • Submitted January 18, 2013.
  • Accepted July 8, 2013.