Efficacy of continuous infusion 2-CDA (cladribine) in pediatric patients with Langerhans cell histiocytosis.

Patients with Langerhans cell histiocytosis (LCH) may behave differently depending on what sites are involved and the response or lack of response to earlier therapies. Therapy for high-risk patients or those with multiple reactivations continues to be challenging because of variable response rates and frequent toxicities. The goals of this study were to determine the long-term disease free survival in children with high-risk or multiply reactivated LCH treated with 2-CDA, and the toxicity of low dose continuous infusion (CI). Ten children with multiple reactivations or high-risk disease as defined by the Histiocyte Society were treated with CI 2-CDA and were evaluable for response and toxicity assessment. The starting dose of 2-CDA was 5 mg/M(2)/day for 3 days and escalated to 6.5 mg/M(2)/day for 3 days if tolerated. The maximum number of courses of 2-CDA per patient was limited to six. Fifty-two courses of 2-CDA were administered without difficulty. After the patient demonstrated no acute toxicity with the first administration of 2-CDA, the subsequent doses were given at home to all but one patient. All 10 patients had a clinical response, 9 documented by radiographic, or changes in physical exam or review of systems. Toxicity was limited to myelosuppression. Seven of the 10 patients required no additional therapy and remain disease free a median of 50 months from completing therapy. The three remaining patients are currently disease free after receiving other therapy. Further studies are needed to determine the role of 2-CDA in this patient population. 2-CDA can be given safely using home therapy, and may effective even in high-risk patients. Copyright 2004 Wiley-Liss, Inc.