Abstract 2751: Development of a specific Wee-1 inhibitor

Abstract Somatic mutations in the TP53 gene are one of the most frequent alterations in human cancers. The resulting TP53-deficient cancer cells rely on WEE1 to trigger a G2/M arrest, which allows for DNA repair and survival. Inhibition of WEE1 has therefore emerged as an attractive therapeutic strategy to selectively sensitise TP53-deficient tumours to DNA damaging agents. The WEE1 kinase inhibitor adavosertib is the only agent undergoing evaluation in a range of clinical trials to validate this hypothesis. It has also been the tool compound of choice to interrogate WEE1 biology for over a decade. However, recent reports show adavosertib has antiproliferative single agent activity, which is counter intuitive considering its postulated mode of action. Other studies suggest adavosertib exerts poor kinase selectivity, and inhibits PLK1 with similar potency as WEE1. Since PLK1 is a well-established mitotic regulator with biological functions throughout the cell cycle, its inhibition may contribute to the clinical efficacy and toxicity observed for adavosertib. Other reported WEE1 inhibitors also suffer from low selectivity and single agent toxicity, making then unsuitable tool compounds. There is a clear need to identify a selective Wee1 tool compound. Using a structure-based drug design approach, we exploited subtle active site differences to identify novel, potent WEE1 inhibitors that display high selectivity over PLK1. These compounds allowed us to demonstrate the distinct effects of WEE1 and PLK1 inhibition on cellular toxicity, and confirm that adavosertib’s single agent efficacy is unlikely to be mediated solely through the inhibition of WEE1. Our ongoing studies aim to provide a WEE1 selective tool compound that more rigorously probes WEE1 biology, and eventually leads to the development of less toxic therapeutic agents. Citation Format: Mandy Watson, Tom Pesnot, Andrew Scott, Anthony Huxley, Gary Nelson, Montserrat Shelbourne, Jen Morton, Tilly Bingham. Development of a specific Wee-1 inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2751.