Abstract 5177: E7386 : First-in-class orally active CBP/beta-catenin modulator as an anticancer agent

Carcinogenesis is often accelerated by the aberrant activation of components molecules of Wnt signaling pathway, especially, APC and beta-catenin are frequently reported to be mutated in various cancers. Therefore, Wnt signal pathway is thought to be one of the attractive therapeutic targets. PRI-724 generated by PRISM Pharma is a small molecule inhibitor of beta-catenin and its transcriptional coactivator CREB binding protein (CBP) thereby specific modulating Wnt/beta-catenin signaling pathway by intravenous continuous infusion. Here we firstly generated orally active small molecular inhibitor, E7386. E7386 disrupted the interaction between beta-catenin and CBP in co-immunoprecipitation assay. E7386 inhibited canonical Wnt signaling pathway /TCF reporter gene activity in LiCl-stimulated HEK-293 and MDA-MB-231 in a dose dependent manner with IC 50 values of 55 nmol/L and 73 nmol/L, respectively. E7386 modulated the expression of Wnt signaling pathway related genes including AXIN2 and other genes, which were down-regulated by artificial knockdown of beta-catenin. These results indicate that E7386 controls the expression of Wnt target genes through modulation of beta-catenin/CBP interaction. Next we investigated anti-polyposis effect in Apc Min/+ mice as an in vivo proof of mechanism model. Apc Min/+ mice develops polyps in the intestinal tract caused by the aberrant activation of Wnt/beta-catenin signaling pathway. Oral administration of E7386 significantly suppressed the number of polyposis in a dose dependent manner at the dose range from 8.5 to 50 mg/kg. In addition, E7386 significantly changed the expressions of Wnt related genes in whisker follicle of Apc Min/+ mice model. Finally, we investigated anti-tumor activity of E7386 in vitro tumor proliferation panel against 28 human tumor cell lines. E7386 showed relatively potent anti-proliferative activity against cancer cell lines harboring exclusively mutated Wnt signaling pathway molecules such as APC or beta-catenin. E7386 also showed significant antitumor activity in a dose dependent manner on human tumor cell line xenograft harboring APC mutation. Taken together, E7386 is a first in class orally active CBP/beta-catenin modulator and showed potent inhibitory activity against aberrant activation of Wnt/beta-catenin signaling pathway. Citation Format: Kazuhiko Yamada, Yusaku Hori, Atsumi Yamaguchi, Masahiro Matsuki, Shuntaro Tsukamoto, Akira Yokoi, Taro Semba, Yoichi Ozawa, Satoshi Inoue, Yuji Yamamoto, Kentaro Iso, Kazutaka Nakamoto, Hitoshi Harada, Naoki Yoneda, Atsushi Takemura, Masayuki Matsukura,, Kenji Kubara, Takenao Odagami, Masao Iwata, Akihiko Tsuruoka, Toshimitsu Uenaka, Junji Matsui, Tomohiro Matsushima, Kenich Nomoto, Hiroyuki Kouji, Takashi Owa. E7386 : First-in-class orally active CBP/beta-catenin modulator as an anticancer agent [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 5177. doi:10.1158/1538-7445.AM2017-5177