The efficacy of imatinib mesylate in patients with FIP1L1-PDGFRalpha-positive hypereosinophilic syndrome. Results of a multicenter prospective study.
OBJECTIVE
The hypereosinophilic syndrome (HES) may be associated with the fusion of the platelet derived growth factor receptor a (PDGFRalpha) gene with the FIP1L1 gene in chromosome 4 coding for a constitutively activated PDGFRalpha tyrosine kinase. These cases with FIP1L1-PDGFRalpha rearrangement have been reported to be very sensitive to the tyrosine kinase inhibitor imatinib mesylate.


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-PDGFRalpha 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.


CONCLUSIONS
All patients meeting the criteria for idiopathic or primary HES should be screened for the FIP1L1-PDGFRalpha rearrangement. For all patients with this rearrangement, chronic imatinib treatment at doses as low as 100 mg daily ensures complete and durable responses.
Baccarani
Michele
M
Department of Hematology-Oncology L. and A. Seràgnoli, S.Orsola-Malpighi University Hospital, Bologna, Italy. michele.baccarani@unibo.it
Cilloni
Daniela
D
Rondoni
Michela
M
Ottaviani
Emanuela
E
Messa
Francesca
F
Merante
Serena
S
Tiribelli
Mario
M
Buccisano
Francesco
F
Testoni
Nicoletta
N
Gottardi
Enrico
E
de Vivo
Antonio
A
Giugliano
Emilia
E
Iacobucci
Ilaria
I
Paolini
Stefania
S
Soverini
Simona
S
Rosti
Gianantonio
G
Rancati
Francesca
F
Astolfi
Cinzia
C
Pane
Fabrizio
F
Saglio
Giuseppe
G
Martinelli
Giovanni
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001549:Benzamides; D005260:Female; D015321:Gene Rearrangement; D006801:Humans; D017681:Hypereosinophilic Syndrome / Q000188:drug therapy / Q000235:genetics*; D000068877:Imatinib Mesylate; D008297:Male; D008875:Middle Aged; D015514:Oncogene Proteins, Fusion / Q000235:genetics* / Q000378:metabolism; D010879:Piperazines / Q000627:therapeutic use*; D011446:Prospective Studies; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011743:Pyrimidines / Q000627:therapeutic use*; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics* / Q000378:metabolism; D016896:Treatment Outcome; D039221:mRNA Cleavage and Polyadenylation Factors / Q000235:genetics* / Q000378:metabolism
D000970:Antineoplastic Agents; D001549:Benzamides; D015514:Oncogene Proteins, Fusion; D010879:Piperazines; D011743:Pyrimidines; D039221:mRNA Cleavage and Polyadenylation Factors; D000068877:Imatinib Mesylate; C479819:FIP1L1-PDGFRA fusion protein, human; D011505:Protein-Tyrosine Kinases; D020796:Receptor, Platelet-Derived Growth Factor alpha