Response to immunomodulatory drug-based regimens in heavily pretreated patients with recurrent/refractory adult Langerhans cell histiocytosis

Abstract Purpose: Langerhans cell histiocytosis (LCH) is a clonal histiocytic neoplasm and, because of its rarity in adults, there is no standard treatment for adult LCH. Immunomodulatory drugs (IMiDs) have been used to treat patients with low risk recurrent/refractory LCH but their effectiveness in adult LCH patients is unclear.Methods: We retrospectively evaluated the response rate to IMiDs-based regimens in ten heavily pretreated recurrent/refractory adult LCH patients at Peking Union Medical College Hospital.Results: A total of 10 patients (four males and six females) were included in this study. Median age at diagnosis was 33 years (range, 28–54 years). All patients had multisystem involvement and the median number of organs involved was 5 (range, 5–7). Seven patients had high risk organs involved, including seven patients with liver involvement and one with spleen involvement. All 10 patients had received at least one chemotherapy before the IMiDs-based regimen. The median number of previous lines of chemotherapy was 2 (range, 1–4). Eight patients received thalidomide, dexamethasone and cyclophosphamide, and two patients received lenalidomide and dexamethasone. The median time that patients received thalidomide treatment was 15 months and the duration of the two patients on lenalidomide regimen was 3 months and 12 months separately. Treatment responses in eight recurrent LCH patients included non-active disease in one patient and regressive disease in seven patients. The two refractory patients who had progression during the last treatment had stable disease after IMiDs therapy. During a median 15-months follow-up period, no disease reactivation or death was observed.Conclusions: IMiDs combined with dexamethasone and cyclophosphamide, may be a salvage therapy for recurrent/refractory adult LCH patients.