Anti TNF- therapy in patients with relapsed and refractory Langerhans cell histiocytosis: a phase II study

Tumor necrosis factor alpha (TNF-) is produced in Langerhans cell histiocytosis (LCH) lesions and is elevated in plasma of patients with active LCH. It has been postulated that TNF- may play a role in the pathophysiology of LCH. Etanercept, an anti-TNF- antibody, has been used in TNF-modulated diseases such as rheumatoid arthritis (RA). We conducted a phase II study to determine the efficacy of etanercept for patients with refractory or relapsed LCH. Five LCH patients who had failed at least 2 prior treatments (range 2-9) received etanercept at a dose of 0.4mg/kg twice weekly for up to a total of 24 doses. Disease response was assessed at 4 and 8weeks. None of the five patients had improvement in their disease with etanercept treatment. Three progressed at week 4 and 1 progressed at week 8. One subject died after 3weeks of treatment from disease progression. During the study, only one drug-related toxicity was noted which spontaneously resolved. The study was concluded early due to lack of response to etanercept and insufficient accrual rate. This data suggests that etanercept as given in this study may not be effective for relapsed or refractory LCH. However, the number of patients treated was not adequate enough to power this study and it is possible that a different dose and regimen of etanercept may be required to successfully treat this disease.