635702-64-6

Description

The growth of solid tumors is dependent on angiogenesis, the process wherein new capillaries are formed from existing blood vessels. VEGF is one of the most important inducers of angiogenesis and expressed at high levels by most tumors. Hence, the inhibition of VEGF or its receptor signaling system is an attractive target for cancer therapeutics. The most studied and developed inhibitors are monoclonal antibodies that neutralize VEGF (e.g., bevacizumab), anti-VEGF ribozymes (e.g., angiozyme), and small-molecule VEGFR kinase inhibitors (e.g., sunitinib, sorafenib). Pazopanib is the latest VEGFR kinase inhibitor to reach the market. It is indicated for the oral treatment of advanced RCC. The biological functions of the VEGF family are mediated by activation of three structurally homologous tyrosine kinase receptors, VEGFR-1, VEGFR-2, and VEGFR3. In vitro, pazopanib inhibits VEGFR-1, VEGFR-2, and VEGFR-3 with IC50 values of 10, 30, and 47 nM, respectively. In addition, it inhibits several of the closely related tyrosine receptor kinases, including platelet-derived growth-factor receptor β(PDGFR-β), c-kit, and fibroblast growth factor receptor-1 (FGFR1) with IC50 values of 84, 74, and 140 nM, respectively. In human umbilical vein endothelial cells (HUVEC), pazopanib inhibits VEGF-induced proliferation more potently than basic fibroblast growth factor (bFGF)-stimulated proliferation (IC50 = 21 nM vs. 721 nM) and concentration-dependently inhibits VEGF-induced VEGFR-2 phosphorylation (IC50 = 7 nM). It also potently inhibits angiogenesis in Matrigel plug and corneal micropocket assays. The most common adverse events associated with pazopanib were diarrhea, hypertension, hair depigmentation, nausea, anorexia, and vomiting.

Originator

GlaxoSmithKline (US)

Uses

Pazopanib Hydrochloride (GW786034, Votrient, Armala) is a novel multi-target inhibitor of VEGFR1, VEGFR2, VEGFR3, PDGFR, FGFR, c-Kit and c-Fms with IC50 of 10 nM, 30 nM, 47 nM, 84 nM, 74 nM, 140 nM and 146 nM, respectively.

Definition

ChEBI: A hydrochloride salt prepared from equimolar amounts of pazopanib and hydrochloric acid. Used for treatment of kidney cancer.

Brand name

Votrient

Clinical Use

Pazopanib is a potent and selective multi-targeted receptor tyrosine kinase inhibitor of VEGFR-1, VEGFR-2, VEGFR-3, PDGFR-a/b, and c-kit that blocks tumor growth and inhibits angiogenesis. It was approved for renal cell carcinoma by the U.S. Food and Drug Administration in 2009 and is marketed under the trade name Votrient by the drug’s manufacturer, GlaxoSmithKline.

Side effects

Pazopanib is synthesized in five chemical steps starting from 3-methyl-6-nitroindazole, which is converted to the corresponding 2,3-dimethylindazole analog via N-methylation with trimethyloxonium tetrafluoroborate. Subsequent reduction of the nitro group to the amino group using tin chloride followed by condensation with 2,4dichloropyrimidine yields a chloropyrimidinylaminoindazole intermediate. The final two steps leading up to pazopanib consist of an N-methylation reaction using iodomethane and cesium carbonate followed by condensation with 5-amino-2-methylbenzenesulfonamide.

Synthesis

The synthesis of pazopanib begins with methylation of 3-methyl-6- nitroindazole (82) with trimethyl orthoformate in the presence of BF3·OEt to give indazole 83 in 65% yield. Reduction of the nitro group was achieved via transfer hydrogenation to give 84 in 97% yield, and this was followed by coupling the aniline with 2,4-dichloropyrimidine in a THF-ethanol mixture at elevated temperature to provide diarylamine 85 in 90% yield. The aniline nitrogen was then methylated using methyl iodide to give 86 in 83% yield prior to coupling with 5-amino-2-methylbenzenesulfonamide (87) and salt formation using an alcoholic solution of HCl to furnish pazopanib hydrochloride (XIV) in 81% yield.