SHP2 is a nonreceptor protein tyrosine phosphatase encoded by the PTPN11 gene and is involved in cell growth and differentiation via the MAPK signaling pathway. SHP2 also plays an important role in the programed cell death pathway (PD-1/PD-L1). As an oncoprotein as well as a potential immunomodulator, controlling SHP2 activity is of high therapeutic interest. As part of our comprehensive program targeting SHP2, we identified multiple allosteric binding modes of inhibition and optimized numerous chemical scaffolds in parallel. In this drug annotation report, we detail the identification and optimization of the pyrazine class of allosteric SHP2 inhibitors. Structure and property based drug design enabled the identification of protein–ligand interactions, potent cellular inhibition, control of physicochemical, pharmaceutical and selectivity properties, and potent in vivo antitumor activity. These studies culminated in the discovery of TNO155, (3S,4S)-8-(6-amino-5-((2-amino-3-chloropyridin-4-yl)­thio)­pyrazin-2-yl)-3-methyl-2-oxa-8-azaspiro­[4.5]­decan-4-amine (1), a highly potent, selective, orally efficacious, and first-in-class SHP2 inhibitor currently in clinical trials for cancer.

SHP2 is a nonreceptor protein tyrosine phosphatase within the mitogen-activated protein kinase (MAPK) pathway controlling cell growth, differentiation, and oncogenic transformation. SHP2 also participates in the programed cell death pathway (PD-1/PD-L1) governing immune surveillance. Small-molecule inhibition of SHP2 has been widely investigated, including in our previous reports describing SHP099 (2), which binds to a tunnel-like allosteric binding site. To broaden our approach to allosteric inhibition of SHP2, we conducted additional hit finding, evaluation, and structure-based scaffold morphing. These studies, reported here in the first of two papers, led to the identification of multiple 5,6-fused bicyclic scaffolds that bind to the same allosteric tunnel as 2. We demonstrate the structural diversity permitted by the tunnel pharmacophore and culminated in the identification of pyrazolopyrimidinones (e.g., SHP389, 1) that modulate MAPK signaling in vivo. These studies also served as the basis for further scaffold morphing and optimization, detailed in the following manuscript.

The physiological effects of nitroglycerin as a potent vasodilator have long been documented. However, the molecular mechanisms by which nitroglycerin exerts its biological functions are still a matter of intense debate. Enzymatic pathways converting nitroglycerin to vasoactive compounds have been identified, but none of them seems to fully account for the reported clinical observations. Here, we demonstrate that nitroglycerin triggers constitutive nitric oxide synthase (NOS) activation, which is a major source of NO responsible for low-dose (1-10 nM) nitroglycerin-induced vasorelaxation. Our studies in cell cultures, isolated vessels, and whole animals identified endothelial NOS activation as a fundamental requirement for nitroglycerin action at pharmacologically relevant concentrations in WT animals.endothelial NOS ͉ neuronal NOS ͉ blood pressure I t has been Ͼ150 years since the effect of nitroglycerin as a potent vasodilator was first reported (1). Since then, intense research has led to extensive and well documented literature regarding nitroglycerin's physiological effects (2-4) and the identity of its derived metabolites in cells, tissues, laboratory animals, and humans (5, 6). Although much of nitroglycerin's pharmacology is known, the mechanisms through which nitroglycerin acts on the endothelium and the heart as well as the enzymatic pathways leading to its bioactivation are still controversial and under intense investigation. A number of hypotheses for nitroglycerin bioconversion in vivo have been formulated, implicating a multitude of enzymes such as GST (6, 7), oxidoreductases (8), and mitochondrial aldehyde dehydrogenase (9, 10) in the bioconversion of nitroglycerin to NO and/or other vasoactive compounds. For example, GST has been shown to catalyze the transnitration of lower thiols in the presence of nitroglycerin (6, 7). Xanthine oxidase and mitochondrial aldehyde dehydrogenase (which are closely related oxidoreductases) have been found to mediate nitroglycerin reduction to nitrite (11) and NO itself (8, 10). Several intermediate compounds, such as partially nitrated glycerin, nitrite (11), and nitrosothiols (6, 7), have been indicated as precursors of nitroglycerin-derived NO, which is ultimately responsible for the observed effects on the vasculature. Collectively, these studies contributed to establishing nitroglycerin as a metabolismdependent NO donor. Although some pathways have received more attention than others, none of the above-mentioned mechanisms seems to satisfactorily delineate nitroglycerin's peculiar kinetic and pharmacological behavior, which is distinct from that of other well characterized NO donors such as sodium nitroprusside (12). For instance, the nitrate groups of nitroglycerin are chemically resistant to rapid reduction because they are esters of nitrate. Also, minute doses of nitroglycerin [maximum plasma concentration Ϸ6 nM for 0.5 mg of nitroglycerin administered sublingually (13)], which are comparable to the basal levels of free NO [Ϸ5 nM as free NO (14)], result in...

Overexpression of the antiapoptotic members of the Bcl-2 family of proteins is commonly associated with cancer cell survival and resistance to chemotherapeutics. Here, we describe the structure-based optimization of a series of N-heteroaryl sulfonamides that demonstrate potent mechanism-based cell death. The role of the acidic nature of the sulfonamide moiety as it relates to potency, solubility, and clearance is examined. This has led to the discovery of novel heterocyclic replacements for the acylsulfonamide core of ABT-737 and ABT-263.