Treatment of Hypereosinophilic Syndrome (HES) with Imatinib Mesylate
Reviewer: Tracy d'Entremont, MD
Last Modified: December 9, 2002
Presenter: Jorge E. Cortes
Presenter's Affiliation: M.D. Anderson Cancer Center; Houston, TX
Type of Session: Scientific
- HES is a rare hematologic disorder characterized by persistent eosinophilia associated with organ involvement.
- The diseasae is very heterogenous but, patients tend to have a poor prognosis.
- Treatment for HES has included steroids and chemotherapeutic agents such as: cyclophosphamide, vincristine, hydroxyurea, and interferon-alpha(IFN).
- Imatinib is a specific tyrosine kinase inhibitor against c-abl, bcr-abl, c-kit, and PDGF-R.
- Eosinophils express c-kit receptor and activation of this receptor leads to eosinophil proliferation.
- For these reasons this study was performed to investigate the efficacy of imatinib in patients with HES.
Materials and Methods
- This was a phase II study of HES patients.
- Patients were initially treated with 100mg of imatinib daily.
- If no response was seen after 4 weeks, the dose was escalated to 400mg/day.
- 9 patients have been enrolled to date (6 males and 3 females) all with end-organ involvement (CNS, skin, or cardiac)
- There have been 4 CR (44%)--all males
- There has been one transient response in a female
- There was one early discontinuation for exacerbation of psoriasis.
- There has been one death after 9 weeks of treatment from pneumococcal sepsis in a patient who had had prior splenectomy.
- Other adverse events were mild with only 2 patients experiencing grade 3 toxicities.
1 with grade 3 rash
1 with grade 3 abdominal cramps and nausea
- Other toxicities were mild grade 1 and included edema, diarrhea, muscle cramps and nausea.
- Imatinib at low dose is efficacious for HES especially in male patients.
- HES is a rare disorder with few effective therapeutic oiptions. This small phase II single institution study is intriguing and may provide a therapeutic option for a select group of HES patients. Though the data are encouraging, the numbers are very small and more patients are required before clinical practice will change.
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