An oral androgen receptor PROTAC degrader for prostate cancer.

Authors

null

Taavi K Neklesa

Arvinas, New Haven, CT

Taavi K Neklesa , Lawrence B Snyder , Mark Bookbinder , Xin Chen , Andrew P Crew , Craig M Crews , Hanqing Dong , Deborah A Gordon , Kanak Raina , AnnMarie K Rossi , Ian Taylor , Nicholas Vitale , Jing Wang , Ryan R Willard , Kurt Zimmermann

Organizations

Arvinas, New Haven, CT, Yale University, New Haven, CT

Research Funding

Pharmaceutical/Biotech Company

Background: 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. Methods: 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. Results: Our lead oral AR PROTAC degrades 92-98% of total AR in all cell lines tested, with 50% degradation concentration (DC50) < 1 nM. AR degradation suppresses the expression of AR-target gene PSA, inhibits cell proliferation, and induces potent apoptosis in VCaP cells. No activity is observed in AR-null cell lines, such as PC-3. While enzalutamide loses its activity in the presence of elevated androgens, AR PROTAC maintains its antiproliferative activity. Further, AR PROTAC is able to degrade all clinically relevant mutant AR proteins. A robust oral bioavailability is observed across multiple species and overall ADME properties are encouraging. Approximately 95% AR degradation is observed in AR-amplified VCaP xenografts at doses as low as 10 mg/kg. Congruent with AR degradation, a dose responsive tumor growth inhibition is observed in AR-dependent xenograft studies. Conclusions: In summary, we report the first orally bioavailable AR PROTAC that robustly degrades AR in vitro and in vivo.

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Abstract Details

Meeting

2017 Genitourinary Cancers Symposium

Session Type

Poster Session

Session Title

Poster Session B: Prostate Cancer and Urothelial Carcinoma

Track

Prostate Cancer,Urothelial Carcinoma,Prostate Cancer

Sub Track

Prostate Cancer - Advanced Disease

Citation

J Clin Oncol 35, 2017 (suppl 6S; abstract 273)

DOI

10.1200/JCO.2017.35.6_suppl.273

Abstract #

273

Poster Bd #

D13

Abstract Disclosures