A tyrosine kinase created by fusion of the PDGFRA and FIP1L1 genes as a therapeutic target of imatinib in idiopathic hypereosinophilic syndrome

Jan Cools, Daniel J. DeAngelo, Jason Gotlib, Elizabeth H. Stover, Robert D. Legare, Jorges Cortes, Jeffrey Kutok, Jennifer Clark, Ilene Galinsky, James D. Griffin, Nicholas C.P. Cross, Ayalew Tefferi, James Malone, Rafeul Alam, Stanley L. Schrier, Janet Schmid, Michal Rose, Peter Vandenberghe, Gregor Verhoef, Marc BoogaertsIwona Wlodarska, Hagop Kantarjian, Peter Marynen, Steven E. Coutre, Richard Stone, D. Gary Gilliland

Research output: Contribution to journalArticlepeer-review

1422 Scopus citations


BACKGROUND: Idiopathic hypereosinophilic syndrome involves a prolonged state of eosinophilia associated with organ dysfunction. It is of unknown cause. Recent reports of responses to imatinib in patients with the syndrome suggested that an activated kinase such as ABL, platelet-derived growth factor receptor (PDGFR), or KIT, all of which are inhibited by imatinib, might be the cause. METHODS: We treated 11 patients with the hypereosinophilic syndrome with imatinib and identified the molecular basis for the response. RESULTS: Nine of the 11 patients treated with imatinib had responses lasting more than three months in which the eosinophil count returned to normal. One such patient had a complex chromosomal abnormality, leading to the identification of a fusion of the Fip1-like 1 (FIP1L1) gene to the PDGFRα (PDGFRA) gene generated by an interstitial deletion or chromosome 4q12. FIP1L1-PDGFRα is a constitutively activated tyrosine kinase thai transforms hematopoietic cells and is inhibited by imatinib (50 percent inhibitory concentration, 3.2 nM). The FIP1L1-PDGFRA fusion gene was subsequently detected in 9 of 16 patients with the syndrome and in 5 of the 9 patients with responses to imatinib that lasted more than three months. Relapse in one patient correlated with the appearance of a T674I mutation in PDGFRA that confers resistance to imatinib. CONCLUSIONS: The hypereosinophilic syndrome may result from a novel fusion tyrosine kinase FIP1L1-PDGFRα - that is a consequence of an interstitial chromosomal deletion. The acquisition of a T674I resistance mutation at the time of relapse demonstrates that FIP1L1-PDGFRα is the target of imatinib. Our data indicate that the deletion of genetic material may result in gain-of-function fusion proteins.

Original languageEnglish (US)
Pages (from-to)1201-1214
Number of pages14
JournalNew England Journal of Medicine
Issue number13
StatePublished - Mar 27 2003

ASJC Scopus subject areas

  • General Medicine


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