Safety and efficacy of the monoclonal anti-interleukin-5 antibody SCH55700 in the treatment of patients with hypereosinophilic syndrome

Amy D. Klion, Melissa A. Law, Pierre Noel, Yae Jean Kim, Thomas P. Haverty, Thomas B. Nutman

Research output: Contribution to journalArticle

133 Scopus citations


Four patients with hypereosinophilic syndrome (HES) refractory to or intolerant of treatment with conventional therapy were treated with a single 1 mg/kg dose of SCH55700. SCH55700 was extremely well tolerated. Two of the 4 patients responded with a fall in eosinophil counts to within the normal range within 48 hours of receiving the drug, accompanied by marked improvement in clinical signs and symptoms. Response was not predicted by serum interleukin-5 (IL-5) levels or presence of the FIP1L1/PDGFRA mutation. Eosinophil counts remained suppressed for up to 12 weeks after treatment; however, exacerbation of symptoms and eosinophilia above baseline levels occurred as drug levels waned. Reinstitution of treatment with monthly SCH55700 led to decreased eosinophilia and symptomatic improvement, albeit to a lesser degree than that seen after the initial dose. These data suggest that anti-IL-5 therapy may be useful in the treatment of HES irrespective of the underlying etiology, although the observed rebound eosinophilia and attenuation of response require further study.

Original languageEnglish (US)
Pages (from-to)2939-2941
Number of pages3
Issue number8
StatePublished - Apr 15 2004


ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology

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