Tipifarnib (INN,[1]: 213  proposed trade name Zarnestra) is a farnesyltransferase inhibitor.

Farnesyltransferase inhibitors block the activity of the farnesyltransferase enzyme by inhibiting prenylation of the CAAX tail motif, which ultimately prevents Ras from binding to the membrane, rendering it inactive.

[6] The inhibitor is being investigated in patients with HRAS mutant head and neck cancer, peripheral T-cell lymphoma (PTCL), myelodysplastic syndromes (MDS), and chronic myelomonocytic leukemia (CMML).

[7][8][9][10][11] It was previously tested in clinical trials in patients in certain stages of breast cancer.

[13] It was shown on a mouse model of Hutchinson–Gilford progeria syndrome that dose-dependent administration of tipifarnib can significantly prevent both the onset of the cardiovascular phenotype as well as the late progression of existing cardiovascular disease.