The Dual MEK/FLT3 Inhibitor E6201 Exerts Cytotoxic Activity against Acute Myeloid Leukemia Cells Harboring Resistance-Conferring FLT3 Mutations

Cancer Res. 2016 Mar 15;76(6):1528-37. doi: 10.1158/0008-5472.CAN-15-1580. Epub 2016 Jan 28.


Fms-like tyrosine kinase 3 (FLT3) inhibition has elicited encouraging responses in acute myeloid leukemia (AML) therapy. Unfortunately, unless combined with a bone marrow transplant, disease relapse is frequent. In addition to the acquired point mutations in the FLT3 kinase domain that contribute to FLT3 inhibitor resistance, MEK/ERK signaling is persistently activated in AML cells even when FLT3 phosphorylation is continually suppressed. Thus, concomitant targeting of FLT3 and MAPK may potentially exert synergistic activity to counteract the resistance of AML cells to FLT3-targeted therapy. In this study, we investigated the antileukemia activity of a MEK1 and FLT3 dual inhibitor, E6201, in AML cells resistant to FLT3 inhibition. We found that E6201 exerted profound apoptogenic effects on AML cells harboring resistance-conferring FLT3 mutations. This activity appeared to be p53 dependent, and E6201-induced cytotoxicity was retained under hypoxic culture conditions and during coculture with mesenchymal stem cells that mimic the AML microenvironment. Furthermore, E6201 markedly reduced leukemia burden and improved the survival of mice in a human FLT3-mutated AML model. Collectively, our data provide a preclinical basis for the clinical evaluation of E6201 in AML patients harboring FLT3 mutations, including those who relapse following FLT3-targeted monotherapy.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Drug Resistance, Neoplasm / drug effects*
  • Drug Resistance, Neoplasm / genetics
  • Female
  • Humans
  • Lactones / pharmacology*
  • Leukemia, Myeloid, Acute / drug therapy*
  • Leukemia, Myeloid, Acute / genetics
  • MAP Kinase Signaling System / drug effects*
  • MAP Kinase Signaling System / genetics
  • Mice
  • Phosphorylation / drug effects
  • Phosphorylation / genetics
  • Point Mutation / drug effects*
  • Point Mutation / genetics
  • Protein Kinase Inhibitors / pharmacology
  • Signal Transduction / drug effects*
  • Signal Transduction / genetics
  • fms-Like Tyrosine Kinase 3 / antagonists & inhibitors*


  • 14-(ethylamino)-8,9,16-trihydroxy-3,4-dimethyl-3,4,9,19-tetrahydro-1H-2-benzoxacyclotetradecine-1,7(8H)-dione
  • Lactones
  • Protein Kinase Inhibitors
  • FLT3 protein, human
  • fms-Like Tyrosine Kinase 3