The receptor tyrosine kinase AXL has emerged in recent years as an potential oncology target due to its over expression in several types of cancers coupled with its ability to promote tumor growth and metastasis. In order to identify small molecule inhibitors of AXL, we built a homology model of its catalytic domain to virtually screen and identify scaffolds displaying an affinity for AXL. Further computational and structure-based design resulted in the synthesis of a series of 2,4,5-trisubstitued pyrimidines which demonstrated potent inhibition of AXL in vitro (IC50 19 nM) and strongly inhibited the growth of several pancreatic cell lines.

The proto-oncogene proviral integration site for moloney murine leukemia virus (PIM) kinases (PIM-1, PIM-2, and PIM-3) are serine/threonine kinases that are involved in a number of signaling pathways important to cancer cells. PIM kinases act in downstream effector functions as inhibitors of apoptosis and as positive regulators of G1-S phase progression through the cell cycle. PIM kinases are upregulated in multiple cancer indications, including lymphoma, leukemia, multiple myeloma, and prostate, gastric, and head and neck cancers. Overexpression of one or more PIM family members in patient tumors frequently correlates with poor prognosis. The aim of this investigation was to evaluate PIM expression in low- and high-grade urothelial carcinoma and to assess the role PIM function in disease progression and their potential to serve as molecular targets for therapy. One hundred thirty-seven cases of urothelial carcinoma were included in this study of surgical biopsy and resection specimens. High levels of expression of all three PIM family members were observed in both noninvasive and invasive urothelial carcinomas. The second-generation PIM inhibitor, TP-3654, displays submicromolar activity in pharmacodynamic biomarker modulation, cell proliferation studies, and colony formation assays using the UM-UC-3 bladder cancer cell line. TP-3654 displays favorable human ether-à-go-go-related gene and cytochrome P450 inhibition profiles compared with the first-generation PIM inhibitor, SGI-1776, and exhibits oral bioavailability. In vivo xenograft studies using a bladder cancer cell line show that PIM kinase inhibition can reduce tumor growth, suggesting that PIM kinase inhibitors may be active in human urothelial carcinomas.

No abstract

Rather than relying on oxidative phosphorylation for the generation of ATP, human tumor cells primarily utilize aerobic glycolysis to metabolize glucose (the Warburg effect). Pyruvate kinase is a metabolic enzyme that converts phosphoenolpyruvate (PEP) to pyruvate, catalyzing the rate-limiting step of glycolysis. The M1 isoform of pyruvate kinase (PKM1) that is the principal isoform in most adult differentiated tissues, while the PKM2 splice variant is the main isoform in embryonic tissues and in all cancer cells. Unlike the M1 splice form (PKM1), which is found in its tetrameric active form in cells, PKM2 is found in cells as an inactive dimer under normal physiological conditions. Tetramerization of PKM2 requires binding of the allosteric activator fructose-1,6-bisphosphate (FBP), an upstream glycolytic intermediate, resulting in a fully active enzyme. Regulation of PKM2 activity in cancer cells may allow glycolytic intermediates to be diverted into other biosynthetic pathways necessary for biomass production. PKM2 expression enhances tumorigenicity of cells while PKM1 expression represses it. This suggests that activators of PKM2 may have anti-tumor properties by forcing PKM2 to act more like PKM1. We have a series of small molecule PKM2 activators that exhibit low nM activation activity in biochemical and cell-based assays. These compounds increase pyruvate kinase activity in cancer cells and lead to an increase in pyruvate and ATP production. Our studies show that PKM2 activators inhibit the growth of lung cancer cell lines in vitro and in vivo and can reverse the metabolic changes induced by oncogenes such as k-Ras and c-Myc in lung cancer cells. The current lead compound was tested in established subcutaneously implanted A549 lung adenocarcinoma xenografts, where we observed a statistically significant 54% decrease in tumor growth, with no observable toxicity. These data suggest that this class of PKM2 activators is effective as tumor cell metabolic regulators with anti-tumor activity for lung cancer and potentially other malignancies. Citation Format: Brigham L. Bahr, Jenny Stevens, Spencer Squire, Christopher Moreno, Lee T. Call, Bret J. Stephens, Alexis Mollard, Steven L. Warner, David J. Bearss. A novel series of metabolic activators of PKM2 alter oncogene-meditated changes in tumor cell metabolism. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1875. doi:10.1158/1538-7445.AM2013-1875