A purine nucleoside antimetabolite analogue. Cladribine triphosphate, a phosphorylated metabolite of cladribine, incorporates into DNA, resulting in single-strand breaks in DNA, depletion of nicotinamide adenine dinucleotide (NAD) and adenosine triphosphate (ATP), and apoptosis. Because this agent is resistant to adenosine deaminase, an enzyme that inactivates some antineoplastic agents, it is selectively toxic to lymphocytes and monocytes which exhibit little deoxynucleotide deaminase activity. OR A substance being studied in the treatment of some types of cancer. It is a monoclonal antibody that is made in the laboratory and can bind to substances in the body. Cixutumumab blocks the action of a protein needed for cell growth and may kill cancer cells. It is a type of insulin-like growth factor-1 receptor (IGF-1R) inhibitor. Also called IMC-A12.