FIP1L1-PDGFRalpha D842V, a novel panresistant mutant, emerging after treatment of FIP1L1-PDGFRalpha T674I eosinophilic leukemia with single agent sorafenib

Leukemia. 2009 May;23(5):845-51. doi: 10.1038/leu.2009.2. Epub 2009 Feb 12.


Chronic eosinophilic leukemia (CEL) is a rare myeloproliferative neoplasm characterized by the FIP1L1-PDGFRA fusion gene, variant PDGFRA fusions or other genetic lesions. Most FIP1L1-PDGFRA positive patients enjoy durable and complete molecular responses to low-dose imatinib (Glivec/Gleevec). However, resistance mediated by a T674I mutation in the ATP-binding pocket of PDGFRA has been reported in advanced disease, and sorafenib, a potent inhibitor of RAF-1, B-RAF, VEGFR and PDGFR, is active against this mutant in vitro. We describe a case of FIP1L1-PDGFRalpha T674I CEL in blast crisis that responded to sorafenib (Nexavar). However, this clinical response was short-lived because of the rapid emergence of a FIP1L1-PDGFRalpha D842V mutant. An N-Nitroso-N-ethylurea-mutagenesis screen indeed identified this mutant as a major sorafenib-resistant mutant. In vitro, the novel FIP1L1-PDGFRalpha D842V mutant is highly resistant to sorafenib, imatinib, dasatinib (Sprycell) and PKC412 (Midostaurin). Thus, sorafenib is clinically active in imatinib-resistant FIP1L1-PDGFRalpha T674I CEL, but the rapid emergence of other mutants may limit the response duration. The identification of new PDGFR inhibitors will be required to overcome resistance by this D842V mutant.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Animals
  • Benzenesulfonates / therapeutic use*
  • Blast Crisis
  • Blotting, Western
  • Cells, Cultured
  • Chronic Disease
  • Drug Resistance, Neoplasm*
  • Humans
  • Hypereosinophilic Syndrome / drug therapy*
  • Hypereosinophilic Syndrome / genetics*
  • Hypereosinophilic Syndrome / metabolism
  • Male
  • Mice
  • Mutation / genetics*
  • Niacinamide / analogs & derivatives
  • Oncogene Proteins, Fusion / genetics*
  • Phenylurea Compounds
  • Phosphorylation / drug effects
  • Precursor Cells, B-Lymphoid / cytology
  • Precursor Cells, B-Lymphoid / drug effects
  • Precursor Cells, B-Lymphoid / metabolism
  • Protein Kinase Inhibitors / therapeutic use*
  • Pyridines / therapeutic use*
  • Receptor, Platelet-Derived Growth Factor alpha / genetics*
  • Receptors, Vascular Endothelial Growth Factor / antagonists & inhibitors
  • Receptors, Vascular Endothelial Growth Factor / metabolism
  • Salvage Therapy
  • Sorafenib
  • mRNA Cleavage and Polyadenylation Factors / genetics*


  • Benzenesulfonates
  • Oncogene Proteins, Fusion
  • Phenylurea Compounds
  • Protein Kinase Inhibitors
  • Pyridines
  • mRNA Cleavage and Polyadenylation Factors
  • Niacinamide
  • Sorafenib
  • FIP1L1-PDGFRA fusion protein, human
  • Receptor, Platelet-Derived Growth Factor alpha
  • Receptors, Vascular Endothelial Growth Factor