A nonpeptidomimetic quinolinone with potential antineoplastic activity. Tipifarnib binds to and inhibits the enzyme farnesyl protein transferase, an enzyme involved in protein processing (farnesylation) for signal transduction. By inhibiting the farnesylation of proteins, this agent prevents the activation of Ras oncogenes, inhibits cell growth, induces apoptosis, and inhibits angiogenesis. OR A substance that is being studied in the treatment of acute myeloid leukemia (AML) and other types of cancer. It belongs to the family of drugs called farnesyltransferase inhibitors. Also called R115777 and Zarnestra.