Relapse following discontinuation of imatinib mesylate therapy for FIP1L1/PDGFRA-positive chronic eosinophilic leukemia: Implications for optimal dosing

Amy D. Klion, Jamie Robyn, Irina Maric, Weiming Fu, Laura Schmid, Steven Lemery, Pierre Noel, Melissa A. Law, Marilyn Hartsell, Cheryl Talar-Williams, Michael P. Fay, Cynthia E. Dunbar, Thomas B. Nutman

Research output: Contribution to journalArticle

82 Scopus citations

Abstract

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 deescalation, 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.

Original languageEnglish (US)
Pages (from-to)3552-3556
Number of pages5
JournalBlood
Volume110
Issue number10
DOIs
StatePublished - Nov 15 2007

ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology

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    Klion, A. D., Robyn, J., Maric, I., Fu, W., Schmid, L., Lemery, S., Noel, P., Law, M. A., Hartsell, M., Talar-Williams, C., Fay, M. P., Dunbar, C. E., & Nutman, T. B. (2007). Relapse following discontinuation of imatinib mesylate therapy for FIP1L1/PDGFRA-positive chronic eosinophilic leukemia: Implications for optimal dosing. Blood, 110(10), 3552-3556. https://doi.org/10.1182/blood-2007-07-100164