PF-562271 is a potent, ATP-competitive, reversible inhibitor of FAK with IC50 of 1.5 nM in cell-free assays, ~10-fold less potent for Pyk2 than FAK and >100-fold selectivity against other protein kinases, except for some CDKs.(In Vitro):PF-562271 (VS-6062) is shown to be a 30- to 120-nM inhibitor of CDK2/E, CDK5/p35, CDK1/B, and CDK3/E in recombinant enzyme assays, in cell-based assays evaluating the role of CDKs, a 48-hour exposure of 3.3 μM PF-562271 is required to alter cell cycle progression. PF-562271 is potent in an inducible cell-based assay measuring phospho-FAK with a IC50 of 5 nM.PF-562271, a selective inhibitor of both FAK and proline-rich tyrosine kinase 2 (PYK2), a FAK-related family member, on cell growth and colony formation in Ewing sarcoma cell lines. Seven cell lines are treated for 5 days with PF-562271 across a range of concentrations using 2-fold serial dilutions. Treatment with PF-562271 impaires cell viability in all cell lines, with an average IC50 of 2.4 μM after 3 days of treatment. TC32 and A673 are the 2 most sensitive cell lines, with IC50 concentrations of 2.1 and 1.7 μM, respectively.(In Vivo):PF-562271 inhibits FAK phosphorylation in vivo in a dose-dependent fashion (calculated EC50 of 93 ng/mL, total) after p.o. administration to tumor-bearing mice. Rats that receive PF-562271 demonstrate a decrease in tumor growth after 2 weeks of treatment with signs of bone healing as evidenced by the deposition of new bone (cortical and cancellous) at sites previously damaged by the tumor.