The efficacy of imatinib mesylate in patients with FIP1L1-PDGFRα- positive hypereosinophilic syndrome. Results of a multicenter prospective study

Michele Baccarani, Daniela Cilloni, Michela Rondoni, Emanuela Ottaviani, Francesca Messa, Serena Merante, Mario Tiribelli, Francesco Buccisano, Nicoletta Testoni, Enrico Gottardi, Antonio De Vivo, Emilia Giugliano, Ilaria Iacobucci, Stefania Paolini, Simona Soverini, Gianantonio Rosti, Francesca Rancati, Cinzia Astolfi, Fabrizio Pane, Giuseppe SaglioGiovanni Martinelli

Research output: Contribution to journalArticle


Background and Objectives: The hypereosinophilic syndrome (HES) may be associated with the fusion of the platelet derived growth factor receptor α (PDGFRα) gene with the FIP1L1 gene in chromosome 4 coding for a constitutively activated PDGFRα tyrosine kinase. These cases with FIP1L1-PDGFRα rearrangement have been reported to be very sensitive to the tyrosine kinase inhibitor imatinib mesylate. Design and Methods: A prospective multicenter study of idiopathic or primary HES was established in 2001 (Study Protocol Registration no. NCT 0027 6929). One hundred and ninety-six patients were screened, of whom 72 where identified as having idiopathic or primary HES and 63 were treated with imatinib 100 to 400 mg daily. Results: Twenty-seven male patients carried the FIP1L1-PDGFRα rearrangement. All 27 achieved a complete hematologic remission (CHR) and became negative for the fusion transcripts according to reverse transcriptase polymerase chain reaction (RT-PCR) analysis. With a median follow-up of 25 months (15-60 months) all 27 patients remain in CHR and RT-PCR negative, and continue treatment at a dose of 100 to 400 mg daily. In three patients imatinib treatment was discontinued for few months, the fusion transcript became rapidly detectable, and then again undetectable upon treatment reassumption. Thirty-six patients did not carry the rearrangement; of these, five (14%) achieved a CHR, which was lost in all cases after 1 to 15 months. Interpretation and Conclusions: All patients meeting the criteria for idiopathic or primary HES should be screened for the FIP1L1-PDGFRα rearrangement. For all patients with this rearrangement, chronic imatinib treatment at doses as low as 100 mg daily ensures complete and durable responses.

Original languageEnglish
Pages (from-to)1173-1179
Number of pages7
Issue number9
Publication statusPublished - Sep 2007



  • Eosinophils
  • Hypereosinophilic syndrome
  • Imatinib
  • Tyrosine kinase

ASJC Scopus subject areas

  • Hematology

Cite this

Baccarani, M., Cilloni, D., Rondoni, M., Ottaviani, E., Messa, F., Merante, S., Tiribelli, M., Buccisano, F., Testoni, N., Gottardi, E., De Vivo, A., Giugliano, E., Iacobucci, I., Paolini, S., Soverini, S., Rosti, G., Rancati, F., Astolfi, C., Pane, F., ... Martinelli, G. (2007). The efficacy of imatinib mesylate in patients with FIP1L1-PDGFRα- positive hypereosinophilic syndrome. Results of a multicenter prospective study. Haematologica, 92(9), 1173-1179.