Multi-centre pilot study of 2-chlorodeoxyadenosine and cytosine arabinoside combined chemotherapy in refractory Langerhans cell histiocytosis with haematological dysfunction.

The aim of this study was to assess the efficacy and adverse effects of 2-chlorodeoxyadenosine (2-CdA) and cytosine arabinoside (Ara-C) in children with refractory Langerhans cell histiocytosis (LCH) and haematopoietic dysfunction. Ten patients, with a median age at diagnosis of 0.5 years, were enrolled in this study. Treatment comprised at least two courses of Ara-C (1000 mg/m(2)/d) and 2-CdA (9 mg/m(2)/d) administered for 5d every 4 weeks; subsequent median follow-up was 2.8 years (range 0.03-6.4 years). Among the 7 patients who received at least two courses of therapy, disease activity decreased in 6 patients, and control of disease was achieved in all patients after a median delay of 5.5 months. All patients suffered World Health Organisation (WHO) grade 4 haematological toxicity. Two septic deaths occurred shortly after administration of the first course of 2-CdA/Ara-C; a third patient was withdrawn from the trial after the first course and subsequently died following haematopoietic stem cell transplantation. This series is small, but we conclude that 2-CdA and Ara-C combined chemotherapy probably has major activity in childhood refractory Langerhans cell histiocytosis.