Despite the number of methods available for dehalogenation and carbon–carbon bond formation using aryl halides, strategies that provide chemoselectivity for systems bearing multiple carbon–halogen ...bonds are still needed. Herein, we report the ability to tune the reduction potential of metal-free phenothiazine-based photoredox catalysts and demonstrate the application of these catalysts for chemoselective carbon–halogen bond activation to achieve C–C cross-coupling reactions as well as reductive dehalogenations. This procedure works both for conjugated polyhalides as well as unconjugated substrates. We further illustrate the usefulness of this protocol by intramolecular cyclization of a pyrrole substrate, an advanced building block for a family of natural products known to exhibit biological activity.
Cowchock syndrome (CMTX4) is a slowly progressive X-linked recessive disorder with axonal neuropathy, deafness, and cognitive impairment. The disease locus was previously mapped to an 11 cM region at ...chromosome X: q24-q26. Exome sequencing of an affected individual from the originally described family identified a missense change c.1478A>T (p.Glu493Val) in AIFM1, the gene encoding apoptosis-inducing factor (AIF) mitochondrion-associated 1. The change is at a highly conserved residue and cosegregated with the phenotype in the family. AIF is an FAD-dependent NADH oxidase that is imported into mitochondria. With apoptotic insults, a N-terminal transmembrane linker is cleaved off, producing a soluble fragment that is released into the cytosol and then transported into the nucleus, where it triggers caspase-independent apoptosis. Another AIFM1 mutation that predicts p.Arg201del has recently been associated with severe mitochondrial encephalomyopathy in two infants by impairing oxidative phosphorylation. The c.1478A>T (p.Glu493Val) mutation found in the family reported here alters the redox properties of the AIF protein and results in increased cell death via apoptosis, without affecting the activity of the respiratory chain complexes. Our findings expand the spectrum of AIF-related disease and provide insight into the effects of AIFM1 mutations.
The clinical benefits of pan-mTOR active-site inhibitors are limited by toxicity and relief of feedback inhibition of receptor expression. To address these limitations, we designed a series of ...compounds that selectively inhibit mTORC1 and not mTORC2. These ‘bi-steric inhibitors’ comprise a rapamycin-like core moiety covalently linked to an mTOR active-site inhibitor. Structural modification of these components modulated their affinities for their binding sites on mTOR and the selectivity of the bi-steric compound. mTORC1-selective compounds potently inhibited 4EBP1 phosphorylation and caused regressions of breast cancer xenografts. Inhibition of 4EBP1 phosphorylation was sufficient to block cancer cell growth and was necessary for maximal antitumor activity. At mTORC1-selective doses, these compounds do not alter glucose tolerance, nor do they relieve AKT-dependent feedback inhibition of HER3. Thus, in preclinical models, selective inhibitors of mTORC1 potently inhibit tumor growth while causing less toxicity and receptor reactivation as compared to pan-mTOR inhibitors.Design of a bivalent inhibitor containing an ATP-competitive moiety and rapamycin-modified FRB binding ligand that selectively inhibits mTORC1 results in potent and durable inhibition of 4EBP1 phosphorylation and cell proliferation in vitro and in vivo.
We present a one-photon visible light-responsive micellar system for efficient, on-demand delivery of small molecules. Release is mediated by a novel class of photochromic material - donor-acceptor ...Stenhouse adducts (DASAs). We demonstrate controlled delivery of small molecules such as the chemotherapeutic agent (paclitaxel) to human breast cancer cells triggered by micellar switching with low intensity, visible light.
The synthesis of sterically hindered anilines has been a significant challenge in organic chemistry. Here we report a Cu-catalyzed radical addition with in situ-generated nitroso compounds to prepare ...sterically hindered amines directly from readily available materials. The transformation is conducted at room temperature, uses abundant copper salts, and is tolerant of a range of functional groups.
Hyperactivation of mTOR kinase by mutations in the PI3K/mTOR pathway or by crosstalk with other mutant cancer drivers, such as RAS, is a feature of many tumors. Multiple allosteric inhibitors of ...mTORC1 and orthosteric dual inhibitors of mTORC1 and mTORC2 have been developed as anticancer drugs, but their clinical utility has been limited. To address these limitations, we have developed a novel class of “bi-steric inhibitors” that interact with both the orthosteric and the allosteric binding sites in order to deepen the inhibition of mTORC1 while also preserving selectivity for mTORC1 over mTORC2. In this report, we describe the discovery and preclinical profile of the development candidate RMC-5552 and the in vivo preclinical tool compound RMC-6272. We also present evidence that selective inhibition of mTORC1 in combination with covalent inhibition of KRASG12C shows increased antitumor activity in a preclinical model of KRAS G12C mutant NSCLC that exhibits resistance to KRASG12C inhibitor monotherapy.
Two cycloaddition strategies are described that lead to various chroman spiroketals from assorted exocyclic enol ethers. Unlike conventional thermodynamic ketalization strategies, the stereochemical ...outcome for this approach is determined by a kinetic cycloaddition reaction. Thus, the stereochemical outcome reflects the olefin geometry of the starting materials along with the orientation of the associated transition state. However, the initial kinetic product can also be equilibrated by acid catalysis and reconstituted into a thermodynamic stereochemical arrangement. Thus, these strategies uniquely enable synthetic access to either the thermodynamic or kinetic conformation of the spiroketal stereocenter itself. Applications of these strategies in the syntheses of berkelic acid, β-rubromycin, and paecilospirone are presented along with the use of a chroman spiroketal for the construction of heliespirones A and C.
Abstract
The PI3K/mTOR and RAS signaling pathways are hyperactivated in a wide range of human cancers. Several points of cross-talk and intersecting feedback mechanisms have been described and ...activation of mTOR signaling frequently mediates escape from RAS pathway inhibition. Revolution Medicines has developed a novel class of selective mTORC1 inhibitors, termed ‘bi-steric inhibitors', that interact with both the ATP- and FKBP12/FRB-binding sites of mTORC1. These compounds potently and selectively inhibit mTORC1 over mTORC2 and other lipid kinases. Unlike rapalogs, such as everolimus, these bi-steric inhibitors suppress 4EBP1 phosphorylation in vivo and induce growth suppression and apoptosis in various genetically-defined preclinical models of human cancer. We will describe our SAR investigations and findings for our preclinical tool compound, RMC-6272 (also known as RM-006) and for RMC-5552, our clinical candidate. We will demonstrate that mTORC1-selective bi-steric inhibitors show combinatorial activity with both KRASG12C(OFF) and KRASG12C(ON) inhibitors, in KRASG12C STK11deficient NSCLC models and can forestall resistance to KRASG12C inhibitor monotherapy. In addition, we will show single agent activity of bi-steric mTORC1 inhibitors in preclinical models of tumors bearing PI3K/mTOR pathway alterations as primary drivers, including PTEN-deficient glioblastoma multiforme, TSC1/2-deficient renal cystadenoma cancer, and hepatocellular cancers harboring mTOR-activating β-catenin mutations. RMC-5552, through reactivation of 4EBP1 and inhibition of cap-dependent translation, has the potential to benefit cancer patients with genetically-defined tumors with activating mutations in the RAS and PI3K/mTOR pathways both as a single agent or in combination with RAS inhibitors.
Citation Format: G. Leslie Burnett. Discovery of RMC-5552: A selective bi-steric inhibitor of mTORC1 that suppresses 4EBP1 phosphorylation, for the treatment of mTORC1-activated tumors including RAS pathway escape abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr ND10.
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