Abstract 4065: Modulation of cancer metabolism with novel PKM2 activators exerts anti-tumor activity
Authors: Behar Vered , Bohana-Kashtan Osnat , Shitrit Alina , Sherman Daniel , Schutz Nili C. , Yakovan Avihai , Becker Oren M. 
Published: August 2014

Abstract
Cancer cells adapt altered metabolism to enable efficient conversion of glucose into biomass needed for massive cell growth and proliferation. The metabolic switch takes place even when oxygen is abundant, a phenomenon known as the Warburg effect. A key mediator of this effect is pyruvate kinase type M2 (PKM2), a rate-limiting enzyme, which catalyzes the last step in glycolysis, converting PEP and ADP to pyruvate and ATP. PKM2 switches between a highly active tetrameric form and low activity monomeric or dimeric forms, following binding to its natural allosteric activator FBP (an upstream glycolytic intermediate). Our goal was to identify novel small molecule PKM2 activators that can be used as potential anti-cancer therapeutics.
Using our proprietary structure-based screening tools, we identified several novel, potent, allosteric PKM2 activators, with AC50s as low as 50nM and 150% activation levels, similar to the natural activator FBP (AC50=116nM, 150% activation). Kinetics studies showed that these compounds significantly improve the rate and efficiency of the enzymatic reaction to the same level as FBP (a 4-fold decrease in KM, and a 2-fold increase in VMAX). Furthermore, a greater increase in VMAX (3-fold) is observed when combining these compounds with FBP. These small-molecule activators induce the formation of the (active) tetrameric form of PKM2, increasing the PKM2 tetramer:monomer ratio by more than 10-fold, quantitatively similar to the action of FBP. In cellular assays, these compounds show significant reduction in the proliferation rate of cancer cell lines, including colorectal, lung and hepatic carcinomas, in a dose- and time-dependent manner (up to 80% proliferation inhibition). In line with the ability of these novel compounds to re-direct cellular metabolism from aerobic glycolysis to oxidative phosphorylation, we found that inhibition of oxidative phosphorylation with oligomycin extends the anti proliferative effect of our compounds. When used in combination with commonly used chemotherapeutic agents, such as 5FU in colorectal cancer cells, they show an additive effect and yielded close to 100% inhibition of cell growth. Our compounds demonstrate excellent in vitro and in vivo DMPK profiles, including metabolic stability, excellent permeability with no efflux (CaCO-2 PApp=20.5 106/cm·s-1), and in vivo mouse pharmacokinetics with 20% oral bioavailability, good half life PO and volume of distribution. Several animal efficacy studies, as mono-therapy and in combination with chemotherapy or specific kinase inhibitors, are ongoing.
Taken together, we present a new class of potent PKM2 activators that modulate the metabolism within cancer cells and show a promising anti cancer therapeutics potential. The favorable DMPK profile of these compounds suggests that they can be further developed either as mono-therapy or in combination with targeted therapeutics or chemo-therapy.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4065. doi:10.1158/1538-7445.AM2011-4065