The transcription factor FOXM1 is up-regulated and overexpressed in aggressive, therapy-resistant forms of hormone receptor-positive and triple negative breast cancers, and is associated with less good patient survival. FOXM1 signaling is also a key driver in many other cancers. Here, we identify a new class of compounds effective in suppressing FOXM1 activity in breast cancers, and displaying good potency for antitumor efficacy. The compounds bind directly to FOXM1 and alter its proteolytic sensitivity, reduce the cellular level of FOXM1 protein by a proteasome-dependent process, and suppress breast cancer cell proliferation and cell cycle progression and increase apoptosis. RNA-seq and gene set enrichment analyses indicate that the compounds decrease expression of FOXM1-regulated genes and suppress gene ontologies under FOXM1 regulation. Several compounds have favorable pharmacokinetic properties and show good tumor suppression in preclinical breast tumor models. These compounds may be suitable for further clinical evaluation in targeting aggressive breast cancers driven by FOXM1.

(Supported by Breast Cancer Research Foundation grant (BCRF-083 to BSK), The Julius and Mary Landfield Cancer Research Fund (to BSK), NIH grant R01 DK015556 (to JAK), NIH T32 GM070421 Fellowship (to VSG), Bankhead-Coley Foundation grant 09BW04 (to DEA), USDA award ILLU-698-909 and National Center for Supercomputing Applications Faculty Fellowship (to ZME), and UIUC Environmental Toxicology Scholarship (to BPS)).

Citation Format: Benita S. Katzenellenbogen, Yvonne Ziegler, Mary J Laws, Valeria S. Guillen, SungHoon Kim, Parama Dey, Brandi P. Smith, Ping Gong, Noah Bindman, Yuechao Zhao, Kathryn Carlson, Mayuri A. Yasuda, Divya Singh, Zhong Li, Dorraya El-Ashry, Zeynep Madak-Erdogan, John A. Katzenellenbogen. Suppression of FOXM1 activities and breast cancer growth in vitro and in vivo by a new class of compounds [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-05-05.