SMYD3 (Set and Mynd Domain containing 3) is a lysine methyltransferase overexpressed in several cancer types including breast, prostrate, pancreatic, and lung, and this overexpression is associated with poor clinical prognosis. Genetic knockdown of SMYD3 by shRNA has been shown to decrease proliferation in a range of cancer cell lines suggesting that inhibition of SMYD3 may have therapeutic utility.

In this presentation we describe the discovery and optimization of a novel series of oxindole sulfonamides and sulfamides with SMYD3 inhibitory activity. One of these compounds, EPZ030456, has a SMYD3 biochemical IC50 of 4 nM and is active in cells with an IC50 of 48 nM in a trimethyl MAP3K2 (MEKK2) in-cell western (ICW) assay. The crystal structure of this compound was solved with SMYD3 and the nucleotide substrate, S-adenosylmethionine and shows the oxindole portion of the molecule extends into the SMYD3 lysine binding channel. EPZ030456 shows < 30% inhibition at a 10 uM screening concentration against 17 histone methyltransferase targets tested, including SMYD2.

Further optimization within the series resulted in EPZ031686 which has similar potency to EPZ030456 with a biochemical IC50 of 3 nM and an ICW IC50 of 36 nM and in addition exhibits good bioavailability following oral dosing in mice. Hence, EPZ031686 is a suitable tool to study the role of SMYD3 in cancer and other therapeutic areas, using both in vitro and in vivo models.

Citation Format: Lorna H. Mitchell, Paula A. Boriack-Sjodin, Sherri Smith, Michael Thomenius, Nathalie Rioux, Michael Munchhof, James E. Mills, Christine Klaus, Jennifer Totman, Thomas V. Riera, Alejandra Raimondi, Suzanne L. Jacques, Megan Foley, Nigel J. Waters, Kevin W. Kuntz, Tim J. Wigle, Margaret Porter Scott, Robert A. Copeland, Jesse J. Smith, Richard Chesworth. Identification of a novel potent selective SMYD3 inhibitor with oral bioavailability. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C85.