Abstract
BackgroundThe FIP1L1/PDGFRA (F/P) fusion gene is the most common clonal genetic abnormality of chronic eosinophilic leukemia (CEL). Tyrosine kinase inhibitors (TKI), such as imatinib, have been demonstrated to be effective therapies for F/P mutated disease. The aim of this study was to analyze the treatment response and long term prognosis in patients with F/P mutated CEL.MethodsThe clinical features and treatment responses of 33 consecutive patients with F/P mutated CEL between August 2006 and October 2014 were analyzed. The 33 cases received imatinib therapy at an initial dose of 100 mg/day (30 patients) or 200 mg/day (3 patients); the maintenance dose depended on the response condition and patient willingness. Through the follow up, the molecular responses were regularly monitored.ResultsWith a median follow up of 64 months, 94% of the 33 patients with F/P mutated CEL achieved a complete hematologic remission (CHR), and 97% achieved a complete molecular remission (CMR) after a median of 3 (1.5-12) months. Twenty-four cases received maintenance therapy, with a median CMR duration of 43 (5-88) months. Imatinib therapy was discontinued in 8 cases, including 4 cases who experienced relapse, and 4 patients who maintained CHR or CMR after discontinuing therapy with a median time of 47 (2-74) months. One case exhibited primary resistance with a PDGFRA T674I mutation.ConclusionsF/P mutated CEL has an excellent long-term prognosis following imatinib therapy. A 100 mg daily dose of imatinib is sufficient to induce remission, and a single 100 mg weekly dose maintains a durable remission. A subgroup of patients may maintain a durable remission after discontinuing therapy with a CMR.
Highlights
FIP1L1/PDGFRA (F/P) rearrangement is the most common molecular abnormality in chronic eosinophilic leukemia (CEL)
Imatinib therapy was discontinued in 8 cases, including 4 cases who experienced relapse, and 4 patients who maintained complete hematologic remission (CHR) or complete molecular remission (CMR) after discontinuing therapy with a median time of 47 (2-74) months
A subgroup of patients may maintain a durable remission after discontinuing therapy with a CMR
Summary
FIP1L1/PDGFRA (F/P) rearrangement is the most common molecular abnormality in chronic eosinophilic leukemia (CEL). According to the specific molecular abnormality, the revised WHO classification in 2008 recognized the myeloid and lymphoid neoplasms with eosinophilia and abnormalities of platelet-derived growth factor receptor (PDGFR) A/B or fibroblast growth factor (FGFR1) as a new subgroup of myeloid neoplasms, which comprise three rare specific disease groups [3]. These 3 diseases www.impactjournals.com/oncotarget result from a fusion gene that encodes an aberrant tyrosine kinase. The aim of this study was to analyze the treatment response and long term prognosis in patients with F/P mutated CEL
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