Study of Clofarabine in Patients With Recurrent or Refractory Langerhans Cell Histiocytosis and LCH-related Disorders

This research study is a Phase II clinical trial. Phase II clinical trials test the effectiveness of an investigational intervention, to learn whether the drug works in treating a specific disease, in this case, clofarabine to treat LCH. "Investigational" means that the intervention is still being studied. It also means that the FDA (the U.S. Food and Drug Administration) has not yet approved clofarabine for your disease. Clofarabine is a chemotherapy drug that has been used and is approved by the FDA for the treatment of leukemia in children and adults. Information from other research studies suggests that this drug may also be effective in participants with LCH and other histiocytic disorders.