Clofarabine is a second-generation nucleoside analog of adenosine. Clofarabine inhibits DNA polymerase and ribonucleotide reductase through binding in the A-site, preventing DNA synthesis. Clofarabine is clinically used to treat acute lymphoblastic leukemia (ALL) and is in clinical trials as a potential treatment for other leukemias. Clofarabine exhibits anticancer chemotherapeutic activity, acting as a cytotoxic agent. Clofarabine also binds A1, A2, and A3 adenosine receptors.