defactinib defactinib defactinib (inn, codenamed vs-6063) is an inhibitor of ptk2, also known as focal adhesion kinase (fak), pyk2, and melk which was developed by pfizer and licensed to verastem oncology as a potential treatment for solid tumors. defactinibskeletal formula and ball-and-stick model of defactinibclinical dataother namespf-04554878, vs-6063legal statuslegal status investigational new drug identifiers iupac name n-methyl-4-pyrazin-2-yl]methylamino]-5-(trifluoromethyl)pyrimidin-2-yl]amino]benzamide cas number1073154-85-4pubchem cid25117126drugbankdb12282chemspider32695161unii53o87ha2qukeggd10618chemblchembl3137331pdb ligand7kd (pdbe, rcsb pdb)chemical and physical dataformulac20h21f3n8o3smolar mass510.50 g·mol−13d model (jsmol)interactive image smiles cnc(=o)c1=cc=c(c=c1)nc2=nc=c(c(=n2)ncc3=nc=cn=c3n(c)s(=o)(=o)c)c(f)(f)f inchi inchi=1s/c20h21f3n8o3s/c1-24-18(32)12-4-6-13(7-5-12)29-19-28-10-14(20(21,22)23)16(30-19)27-11-15-17(26-9-8-25-15)31(2)35(3,33)34/h4-10h,11h2,1-3h3,(h,24,32)(h2,27,28,29,30)key:fwlmvfugmhioaa-uhfffaoysa-n development for mesothelioma was discontinued in 2015 due to lack of efficacy in a placebo-controlled phase ii trial. subsequent research in patients with specific nf2 mutations also found limited activity. as of 2022, it remains in trials in combination with other medications for other types of cancer.