Results of Treatment with 2-Chlorodeoxyadenosine (2-CDA) in Multiple Reactivations or Refractory Langerhans Cell Histiocytosis

Background: Langerhans cell histiocytosis (LCH) is the most common type of histiocytosis and characterized by abnormal proliferation and excess accumulation of inflammatory and langerhans cells at various tissue sites. Clinical manifestations are variable, ranging from spontaneously regressing single bone lesion to multisystem disease, life-threatening and refractory to treatment. Conventional chemotherapy has been shown to be effective in treatment of majority of patients with LCH. However, treatment of refractory disease or multiple reactivations is difficult. The aim of this study is to assess the efficacy of 2-CDA in relapsed or refractory LCH. Materials and methods: Four patients with relapsed or refractory LCH that were treated with 2-chlorodeoxyadenosin (2-CDA) enrolled in this study. All patients had received at least one prior chemotherapy regimen. The dose and schedule of 2-CDA was 6 mg/m²/day for 5 days every 3-4 weeks. Results: Median age at the time of treatment with 2-CDA was 9.7 years. Three patients had multisystem disease and one had multifocal bone lesions. All patients had multifocal bone lesions. None of them had risk organ involvement. Mean course of treatment with 2-CDA was 9.5. Radiologic evaluations revealed complete resolution of bone lesions in two (50%) patients. In one (25%) patient lesions regressed (partial response) and in another (25%) the disease remained stable. Drug related side effects were minimal. At the present time all patients are alive. Conclusion: Our study demonstrates that 2-CDA as a single agent is efficacious in treatment of multiple reactivations or refractory LCH and well-tolerated in children.