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Blood, 15 November 2007, Vol. 110, No. 10, pp. 3552-3556. Prepublished online as a Blood First Edition Paper on August 20, 2007; DOI 10.1182/blood-2007-07-100164. This Article Full Text Full Text (PDF) All Versions of this Article: blood-2007-07-100164v1 110/10/3552    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Klion, A. D. Articles by Nutman, T. B. Search for Related Content PubMed PubMed Citation Articles by Klion, A. D. Articles by Nutman, T. B. Related Collections Neoplasia Oncogenes and Tumor Suppressors Clinical Trials and Observations Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  CLINICAL TRIALS AND OBSERVATIONS Relapse following discontinuation of imatinib mesylate therapy for FIP1L1/PDGFRA-positive chronic eosinophilic leukemia: implications for optimal dosing Amy D. Klion1, Jamie Robyn2,3, Irina Maric4, Weiming Fu4, Laura Schmid1, Steven Lemery2, Pierre Noel4, Melissa A. Law1, Marilyn Hartsell1, Cheryl Talar-Williams1, Michael P. Fay5, Cynthia E. Dunbar2, and Thomas B. Nutman1 1 Laboratory of Parasitic Diseases, National Institutes of Allergy and Infectious Diseases (NIAID), 2 Hematology Branch, National Heart, Lung and Blood Institute (NHLBI); 3 Laboratory of Allergic Diseases, NIAID; 4 Department of Laboratory Medicine, Warren Grant Magnusson Clinical Center; and 5 Biostatistics Research Branch, NIAID, National Institutes of Health (NIH), Bethesda, MD Although imatinib is clearly the treatment of choice for FIP1L1/PDGFRA-positive chronic eosinophilic leukemia (CEL), little is known about optimal dosing, duration of treatment, and the possibility of cure in this disorder. To address these questions, 5 patients with FIP1L1/PDGFRA-positive CEL with documented clinical, hematologic, and molecular remission on imatinib (400 mg daily) and without evidence of cardiac involvement were enrolled in a dose de-escalation trial. The imatinib dose was tapered slowly with close follow-up for evidence of clinical, hematologic, and molecular relapse. Two patients with endomyocardial fibrosis were maintained on imatinib 300 to 400 mg daily and served as controls. All 5 patients who underwent dose de-escalation, but neither of the control patients, experienced molecular relapse (P < .05). None developed recurrent symptoms, and eosinophil counts, serum B12, and tryptase levels remained suppressed. Reinitiation of therapy at the prior effective dose led to molecular remission in all 5 patients, although 2 patients subsequently required increased dosing to maintain remission. These data are consistent with suppression rather than elimination of the clonal population in FIP1L1/PDGFRA-positive CEL and suggest that molecular monitoring may be the most useful method in determining optimal dosing without the risk of disease exacerbation. This trial was registered at http://www.clinicaltrials.gov as no. NCT00044304 [ClinicalTrials.gov] . CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

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