Abstract 5637: An oral Androgen Receptor PROTAC degrader for prostate cancer

The Androgen Receptor (AR) remains the principal driver of castration-resistant prostate cancer during the transition from a localized to metastatic disease. Most patients initially respond to inhibitors of the AR pathway, but the response is often short-lived. The majority of patients progressing on enzalutamide or abiraterone exhibit genetic alterations in the AR locus, either in the form of amplifications or point mutations in the AR gene. Given these mechanisms of resistance, our goal is to eliminate the AR protein using the PROteolysis TArgeting Chimera (PROTAC) technology. Further, we sought to make an orally bioavailable AR PROTAC. Medicinal chemistry efforts yielded a small molecule AR PROTAC that simultaneously binds E3-ubiquitin ligase and AR, thus leading to ubiquitination and degradation of AR. This molecule has been characterized in in vitro and in vivo preclinical studies. Our lead oral AR PROTAC degrades approximately 98% of total AR in all cell lines tested, with 50% degradation concentration (DC50) Citation Format: Taavi K. Neklesa, Lawrence B. Snyder, Mark Bookbinder, Xin Chen, Andrew P. Crew, Craig M. Crews, Hanqing Dong, Deborah Gordon, Jennifer Macaluso, Kanak Raina, AnnMarie Rossi, Ian Taylor, Nicholas Vitale, Jing Wang, Ryan R. Willard, Kurt Zimmermann. An oral Androgen Receptor PROTAC degrader for prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5637. doi:10.1158/1538-7445.AM2017-5637