Tipifarnib (IND 58359) is 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.

Tipifarnib S enantiomer ((S)-(-)-R-115777) is the S-enantiomer of Tipifarnib. Tipifarnib is a potent and specific farnesyltransferase inhibitor (IC50: 0.6 nM).