2-Chlorodeoxyadenosine and cytarabine combination therapy for idiopathic hypereosinophilic syndrome.

Background: Hypereosinophilic syndrome (HES) is a rare, disabling, and incurable disease. In this study, a combination of 2-chlorodeoxyadenosine (2-CdA) and cytosine arabinoside (ara-C) chemotherapy was evaluated in patients with HES.

Methods: Nine patients with HES were treated with ara-C (1 g/m(2)) given intravenously over 2 hours at 0 hours, 48 hours, 72 hours, 96 hours, and 120 hours; and 2-CdA (12 mg/m(2) per day) was given as a continuous intravenous infusion over 5 days starting at 24 hours. A second course of the same therapy was administered in patients who had a response.

Results: All patients had signs and symptoms of end-organ involvement. The median time from diagnosis to therapy was 25 months. Seven patients had received prior therapies. Five patients (55%) achieved a complete remission (CR), 1 after receiving 2 courses of therapy. Elimination of eosinophilia was accompanied by the resolution of symptoms. The median disease-free survival and overall survival after the diagnosis for patients who achieved CR was 26 months and 44 months, respectively. Treatment was tolerated well. Febrile neutropenia occurred in 28% of the 14 courses that were given. The median time to recovery from neutropenia and thrombocytopenia was 17 days and 39 days, respectively.

Conclusions: The combined 2-CdA and ara-C chemotherapy regimen had activity in patients with HES.