Hypereosinophilic Syndrome Medication

Updated: Oct 14, 2020
  • Author: Venkata Anuradha Samavedi, MBBS, MD; Chief Editor: Emmanuel C Besa, MD  more...
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Medication Summary

The goals of pharmacotherapy in patients with hypereosinophilic syndrome (HES) are to reduce morbidity and to prevent complications. Glucocorticoids are the first-line therapy in patients without the FIP1L1/PDGFRA mutation, while imatinib is the first-line choice in patients with the FIP1L1/PDGFRA mutation. Mepolizumab is approved for use in adults and children aged 12 years and older with HES for 6 months or longer without an identifiable nonhematologic secondary cause. A variety of second-line agents may be used for refractory cases.



Class Summary

Corticosteroids often cause a rapid reduction in level of the eosinophilia. The mechanisms for this are not entirely clear.

Prednisone (Deltasone, Rayos)

Initial DOC. Once eosinophils are suppressed, the dose may be slowly tapered. Patients whose condition responds to steroids tend to have a better prognosis.


Antineoplastic Agents

Class Summary

Chemotherapeutic agents may be used in patients whose conditions are refractory to steroid treatment. As a group, antineoplastic agents interfere with the production of eosinophils, but they may also cause toxicity to normal tissues, especially the bone marrow.

Hydroxyurea (Hydrea, Droxia)

Second line of treatment. Goal is to reduce total white blood cell (WBC) count to < 10,000 cells/µL. One week of therapy may be required before a reduction of the eosinophil count is observed. Anemia and thrombocytopenia are common complications associated with this drug.

Vincristine (Vincasar PFS)

May be instituted in patients whose condition fails or is only partially responsive to hydroxyurea. A response is often observed within 1-3 d. Marrow suppression is less common than with hydroxyurea, but occurrence of neurologic toxicity may limit treatment and closely resemble the neurologic symptoms of hypereosinophilic syndrome.

Chlorambucil (Leukeran)

Primary alkylating agent used in cases in which prednisone fails and in those patients who cannot tolerate hydroxyurea or vincristine. A reasonable alternative for long-term treatment. Bone marrow suppression may be a problem.

Etoposide (Toposar)

Etoposide is a glycosidic derivative of podophyllotoxin that exerts a cytotoxic effect by stabilizing the normally transient covalent intermediates formed between the DNA substrate and topoisomerase II. The drug leads to single-stranded and double-stranded DNA breaks that arrest cellular proliferation in the late S or early G2 phase of cell cycle.


An antimetabolite antineoplastic agent, cytarabine is converted intracellularly to the active compound cytarabine-5'-triphosphate, which inhibits DNA polymerase. It is metabolized in the liver, with a half-life of 1-3 h. The agent is widely distributed, including in the central nervous system and tears, after IV administration.

Imatinib (Gleevec)

Imatinib is specifically designed to inhibit the tyrosine kinase activity of bcr-abl kinase in Ph1-positive leukemic CML cell lines. It is well absorbed after oral administration, with maximum concentrations achieved within 2-4 hours. Elimination is primarily in feces in the form of metabolites.



Class Summary

Immunomodulators are naturally produced proteins with antiviral, antitumor, and immunomodulatory actions. Alpha, beta, and gamma interferons may be given topically, systemically, and intralesionally. These agents have demonstrated efficacy in small trials.

Peginterferon alfa 2a (Pegasys, Pegasys ProClick)

Has been reported to effectively suppress eosinophilia in several different patients using several different doses. Some patients have had progression of disease despite therapy.

Interferon alpha-2b (Intron A)

Has been reported to effectively suppress eosinophilia in several different patients using several different doses. Some patients have had progression of disease despite therapy.


Interleukin Inhibitors

Class Summary

Inhibition of binding of interleukin-5 to eosinophils reduces blood, tissue, and sputum eosinophil levels.

Mepolizumab (Nucala)

Humanized IgG1 kappa monoclonal antibody specific for interleukin-5 (IL-5); binds IL-5, and therefore stops IL-5 from binding to its receptor on the surface of eosinophils. Indicated for adults and pediatric patients aged ≥12 years with hypereosinophilic syndrome (HES) for 6 months without an identifiable nonhematologic secondary cause.