Tipifarnib (R-115777) is 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. It is also called Zarnestra. In June 2005, the FDA issued a Not Approvable Letter for Zarnestra.
Humans and other mammals
Investigated for use/treatment in colorectal cancer, leukemia (myeloid), pancreatic cancer, and solid tumors.
R115777, a nonpeptidomimetic farnesyl transferase inhibitor, suppresses the growth of human pancreatic adenocarcinoma cell lines. This growth inhibition is associated with modulation in the phosphorylation levels of signal transducers and activators of transcription 3 (STAT3) and extracellular signal-regulated kinases (ERK).
Mechanism of action
The farnesyltransferase inhibitors (FTIs) are a class of experimental cancer drugs that target protein farnesyltransferase with the downstream effect of preventing the proper functioning of the Ras protein, which is commonly abnormally active in cancer. After translation, RAS goes through four steps of modification: isoprenylation, proteolysis, methylation and palmitoylation. Isoprenylation involves the enzyme farnesyltransferase (FTase) transferring a farnesyl group from farnesyl pyrophosphate (FPP) to the pre-RAS protein. Also, a related enzyme geranylgeranyltransferase I (GGTase I) has the ability to transfer a geranylgeranyl group to K and N-RAS. Farnesyl is necessary to attach RAS to the cell membrane. Without attachment to the cell membrane, RAS is not able to transfer signals from membrane receptors (Reuter et al., 2000).
Drug Info/Drug Targets: DrugBank 3.0: a comprehensive resource for 'omics' research on drugs. Knox C, Law V, Jewison
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