Cladribine is a synthetic anti-cancer drug used to suppress the immune system. Cladribine trades with the name litak, leustatin, or movectro. Cladribine is utilized in the treatment of hairy cell leukemia. Cladribine works by mimicking nucleoside adenosine which interferes with the processing of DNA. Cladribine can also be employed in the treatment of histiocytosis.