Abstract 5681: Design, synthesis and study of small molecules with both AR degradation and AKR1C3 inhibitory activities

Prostate cancer is the most common cancer in men and it is estimated that 32,000 men in the US alone will die of this cancer in 2019. Androgen deprivation therapy (ADT) has been the mainstay of prostate cancer therapy. However, most of the patients will progress to castration resistance prostate cancer (CRPC) after several years of treatment. The current treatment of CRPC includes chemotherapeutic agents (docetaxel) and agents that target androgen signaling (abiraterone, enzalutamide and apalutamide). Ultimately, however, most patients develop resistance to the treatments. Two of the mechanisms of resistance involve the expression of constitutively active androgen receptor variant (AR-V7) and the increase in intra-tumoral biosynthesis of androgens. Several treatment strategies targeting AR-V7 have been reported. For the intra-tumoral biosynthesis of androgens, one of the enzymes, AKR1C3, plays a critical role in the development of CRPC and has been reported to be consistently elevated in CRPC patients who are resistant to abiraterone and enzalutamide. We have been involved in the development of agents to treat CRPC and overcome drug resistance of CRPC patients. We reported that niclosamide, an FDA-approved anthelminthic agent, could degrade AR-V7. We also reported that niclosamide, as well as an AKR1C3 inhibitor, indomethacin, were able to overcome enzalutamide and abiraterone resistance in several prostate cancer cell lines, suggesting that niclosamide is also an AKR1C3 inhibitor. By examining the reported structures of AKR1C3 inhibitors, niclosamide was found to contain the core scaffold of 4-Hydroxy-1-(4-methoxybenzyl)-N-(3-(trifluoromethyl) phenyl)-1H-1,2,3-triazole-5-carboxamide. Using this knowledge, we designed a series compounds with dual AR degrading and AKR1C3 inhibitory activities. Preliminary studies showed the compounds caused AR-V7 degradation and to a lesser extent AR full length degradation. The compounds also inhibited AKR1C3 and caused a dose dependent growth inhibition of several prostate cancer cell lines. Citation Format: Enming Xing, Xiaotian Kong, Wei Lou, Ruihua Shi, Xiaolin Cheng, Allen C. Gao, Pui Kai Li. Design, synthesis and study of small molecules with both AR degradation and AKR1C3 inhibitory activities [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5681.