Discovery and Characterisation of Highly Cooperative FAK-Degrading PROTACs.

Focal adhesion kinase (FAK) is a key mediator of tumour progression and metastasis. To date, clinical trials of FAK inhibitors have reported disappointing efficacy for oncology indications. We report the design and characterisation of GSK215, a potent, selective, FAK-degrading Proteolysis Targeting Chimera (PROTAC) based on a binder for the VHL E3 ligase and the known FAK inhibitor VS-4718. X-ray crystallography revealed the molecular basis of the highly cooperative FAK-GSK215-VHL ternary complex, and GSK215 showed differentiated in vitro pharmacology compared to VS-4718. In mice, a single dose of GSK215 induced rapid and prolonged FAK degradation, giving a long-lasting effect on FAK levels (~96 h) and a marked PK/PD disconnect. This tool PROTAC molecule is expected to be useful for the study of FAK degradation biology in vivo, and our results indicate that FAK degradation may be a differentiated clinical strategy versus FAK inhibition for the treatment of cancer.