Defactinib (VS-6063) is a second-generation inhibitor of FAK that inhibits FAK phosphorylation at the Tyr397 site. Defactinib has potential antitumor activity.

METHODS: Thyroid cancer cell lines TT, K1, BCPAP and TPC1 were treated with Defactinib (1-50 µM) for 24 h and cell viability was measured by MTS assay.
RESULTS: Defactinib reduced cell viability in a dose-dependent manner in TT, K1, BCPAP and TPC1 cell lines with IC50s of 1.98 µM, 10.34 µM, 23.04 µM and >50 µM, respectively.[1]
METHODS: Taxane-sensitive cell line HeyA8 and Taxane-resistant cell line HeyA8-MDR were treated with Defactinib (0.001-10 mM) for 1-48 h, and target protein expression levels were detected by Western Blot.
RESULTS: Defactinib statistically significantly inhibited the expression of pFAK (Tyr397) in a dose-dependent manner. pFAK (Tyr397) expression was inhibited by Defactinib within 3 h and was gradually restored within 48 h. Defactinib was also shown to inhibit pFAK (Tyr397) expression in a dose-dependent manner. [2]

METHODS: To assay antitumor activity in vivo, Defactinib (25 mg/kg orally twice daily) and PTX (2 mg/kg intraperitoneally once weekly) were administered to thymus-free nude mice bearing SKOV3ip1, SKOV3-TR, HeyA8 or HeyA8-MDR xenografts for 35 or 28 days.
RESULTS: In the HeyA8 model, PTX monotherapy resulted in an 87.4% reduction in tumor weight, and combination therapy resulted in the greatest reduction in tumor weight, 97.9% compared with PTX. In the SKOV3ip1 model, tumor weight was reduced by 92.7% in the combination group compared to PTX.Treatment with PTX alone was ineffective in the HeyA8 MDR model and the SKOV3-TR model, but treatment with Defactinib resulted in a reduction in tumor weight of 42.6% and 67.1%, respectively, with the combination leading to an even greater reduction in tumor growth. [2]

Cell-free Kinase Activity Assays: IC50 values for TG101348 are determined commercially using the InVitrogen kinase profiling service for a 223 kinase screen that included JAK2 and JAK2V617F or Carna Biosciences for the screen of all Janus kinase family members including JAK1 and Tyk2. ATP concentration is set to approximately the Km value for each kinase.

Ovarian cancer cells are treated with increasing concentrations of VS-6063 for 96 hours and then subjected to the MTT assay. Results are confirmed with triplicate experiments.(Only for Reference)