Guido Bold

Inhibition of Chronic and Acute Skin Inflammation by Treatment with a Vascular Endothelial Growth Factor Receptor Tyrosine Kinase Inhibitor

Although vascular remodeling is a hallmark of many chronic inflammatory disorders, antivascular strategies to treat these conditions have received little attention to date. We investigated the effects of a newly identified vascular endothelial growth factor (VEGF) receptor tyrosine-kinase inhibitor, NVP-BAW2881, on endothelial cell function in vitro and its anti-inflammatory activity in different animal models. NVP-BAW2881 inhibited proliferation, migration, and tube formation by human umbilical vein endothelial cells and lymphatic endothelial cells in vitro. In a transgenic mouse model of psoriasis, NVP-BAW2881 reduced the number of blood and lymphatic vessels and infiltrating leukocytes in the skin, and normalized the epidermal architecture. NVP-BAW2881 also displayed strong anti-inflammatory effects in models of acute inflammation; pretreatment with topical NVP-BAW2881 significantly inhibited VEGF-A-induced vascular permeability in the skin of pigs and mice. Furthermore, topical application of NVP-BAW2881 reduced the inflammatory response elicited in pig skin by UV-B irradiation or by contact hypersensitivity reactions. These results demonstrate for the first time that VEGF receptor tyrosine-kinase inhibitors might be used to treat patients with inflammatory skin disorders such as psoriasis.

Synthesis and biological evaluation of highly potent analogues of epothilones B and D

A series of new epothilone B and D analogues incorporating fused hetero-aromatic side chains have been prepared. The synthetic strategy is based on olefin 3 as the common intermediate and allows variation of the side-chain structure in a highly convergent and stereoselective manner. Epothilone analogues 1a-d and 2a-d are more potent inhibitors of cancer cell proliferation than the corresponding parent epothilones B or D.

Identification of a new chemical class of potent angiogenesis inhibitors based on conformational considerations and database searching

The vascular endothelial growth factor (VEGF) tyrosine kinase receptors KDR and Flt-1 are targets of current interest in anticancer drug research. PTK787/ZK222584 is a potent inhibitor of these enzymes in clinical evaluation as an antiangiogenic agent. The development of a hypothesis concerning the bioactive conformation of this compound has led to the discovery of a new class of potent inhibitors of KDR and Flt-1, the anthranilamides. This could be achieved with a limited experimental effort, which only involved the testing of one archive compound and the synthesis and testing of one appropriate analogue.

CGP 53437, an orally bioavailable inhibitor of human immunodeficiency virus type 1 protease with potent antiviral activity.

CGP 53437 is a peptidomimetic inhibitor of human immunodeficiency virus type 1 (HIV-1) protease containing a hydroxyethylene isostere. The compound inhibited recombinant HIV-1 protease with a Ki of 0.2 nM. The inhibition constant versus human cathepsin D and human cathepsin E was 4 nM. Human pepsin and gastricsin were inhibited with Kis of 8 and 500 nM, respectively, and human renin was inhibited with a Ki of 190 microM. The replication of HIV-1/LAV, HIV-1/Z-84, and HIV-1/pLAI was inhibited with a 90% effective dose of 0.1 microM in acutely infected MT-2 cells. The 50% cytotoxic dose was 100 microM. Similar antiviral activity was observed when the compound was added up to 10 h after infection. At the effective concentration, processing of Gag precursor protein p55 was greatly reduced, confirming an action on the late stage of the virus life cycle, as expected. The efficacy of the inhibitor was also demonstrated by using primary human peripheral blood lymphocytes infected with the HIV-1/LAV strain, low-passage clinical isolates obtained from HIV-1-seropositive individuals (including a zidovudine-resistant strain), and HIV-2/ROD. In these cells, CGP 53437 delayed the onset of HIV replication in a dose-dependent fashion (substantial effects with concentrations of > or = 0.1 microM) as long as the inhibitor was maintained in the culture. CGP 53437 was orally bioavailable in mice. Concentrations in plasma 10-fold in excess of the in vitro antiviral 90% effective dose could be sustained for several hours after oral application of 120 mg/kg. Therefore, CGP 53437 has the potential to be a therapeutically useful anti-HIV agent for the treatment of AIDS. Images

Antileukemic effects of the novel, mutant FLT3 inhibitor NVP-AST487: effects on PKC412-sensitive and -resistant FLT3-expressing cells

An attractive target for therapeutic intervention is constitutively activated, mutant FLT3, which is expressed in a subpopulation of patients with acute myelocyic leukemia (AML) and is generally a poor prognostic indicator in patients under the age of 65 years. PKC412 is one of several mutant FLT3 inhibitors that is undergoing clinical testing, and which is currently in late-stage clinical trials. However, the discovery of drug-resistant leukemic blast cells in PKC412-treated patients with AML has prompted the search for novel, structurally diverse FLT3 inhibitors that could be alternatively used to override drug resistance. Here, we report the potent and selective antiproliferative effects of the novel mutant FLT3 inhibitor NVP-AST487 on primary patient cells and cell lines expressing FLT3-ITD or FLT3 kinase domain point mutants. NVP-AST487, which selectively targets mutant FLT3 protein kinase activity, is also shown to override PKC412 resistance in vitro, and has significant antileukemic activity in an in vivo model of FLT3-ITD(+) leukemia. Finally, the combination of NVP-AST487 with standard chemotherapeutic agents leads to enhanced inhibition of proliferation of mutant FLT3-expressing cells. Thus, we present a novel class of FLT3 inhibitors that displays high selectivity and potency toward FLT3 as a molecular target, and which could potentially be used to override drug resistance in AML.

Tetra-substituted imidazoles as a new class of inhibitors of the p53–MDM2 interaction

Capitalizing on crystal structure information obtained from a previous effort in the search for non peptide inhibitors of the p53-MDM2 interaction, we have discovered another new class of compounds able to disrupt this protein-protein interaction, an important target in oncology drug research. The new inhibitors, based on a tetra-substituted imidazole scaffold, have been optimized to low nanomolar potency in a biochemical assay following a structure-guided approach. An appropriate strategy has allowed us to translate the high biochemical potency in significant anti-proliferative activity on a p53-dependent MDM2 amplified cell line.

A concise synthesis of aza-dipeptide isosteres

Abstract Aza-dipeptide isosteres as potent HIV-protease inhibitors containing a (hydroxyethyl)-hydrazine moiety are synthesised in >98% diastereomeric and enantiomeric purity starting from (L)-phenylalanine aldehyde.

Novel pseudosymmetric inhibitors of HIV-1 protease

Abstract Compounds containing the easily accessible Phe[CH(OH)CH2N(NH)Phe dipeptide isostere as a non-hydrolyzable replacement of the scissile amide bond in the natural substrate are potent inhibitors of HIV-1 protease. The expected symmetric binding pattern of the most potent inhibitor in this series (CGP 53280, IC50 = 9 nM) is illustrated by the X-ray analysis performed with the corresponding enzyme-inhibitor complex.

Discovery of Novel Allosteric Non-Bisphosphonate Inhibitors of Farnesyl Pyrophosphate Synthase by Integrated Lead Finding.

Farnesyl pyrophosphate synthase (FPPS) is an established target for the treatment of bone diseases, but also shows promise as an anticancer and anti‐infective drug target. Currently available anti‐FPPS drugs are active‐site‐directed bisphosphonate inhibitors, the peculiar pharmacological profile of which is inadequate for therapeutic indications beyond bone diseases. The recent discovery of an allosteric binding site has paved the way toward the development of novel non‐bisphosphonate FPPS inhibitors with broader therapeutic potential, notably as immunomodulators in oncology. Herein we report the discovery, by an integrated lead finding approach, of two new chemical classes of allosteric FPPS inhibitors that belong to the salicylic acid and quinoline chemotypes. We present their synthesis, biochemical and cellular activities, structure–activity relationships, and provide X‐ray structures of several representative FPPS complexes. These novel allosteric FPPS inhibitors are devoid of any affinity for bone mineral and could serve as leads to evaluate their potential in none‐bone diseases.

The T-cell fingerprint of MALT1 paracaspase revealed by selective inhibition

Mucosa‐associated lymphoid tissue lymphoma translocation protein 1 (MALT1) is essential for immune responses triggered by antigen receptors but the contribution of its paracaspase activity is not fully understood. Here, we studied how MALT1 proteolytic function regulates T‐cell activation and fate after engagement of the T‐cell receptor pathway. We show that MLT‐827, a potent and selective MALT1 paracaspase inhibitor, does not prevent the initial phase of T‐cell activation, in contrast to the pan‐protein kinase C inhibitor AEB071. However, MLT‐827 strongly impacted cell expansion after activation. We demonstrate this is the consequence of profound inhibition of IL‐2 production as well as reduced expression of the IL‐2 receptor alpha subunit (CD25), resulting from defective canonical NF‐κB activation and accelerated mRNA turnover mechanisms. Accordingly, MLT‐827 revealed a unique transcriptional fingerprint of MALT1 protease activity, providing evidence for broad control of T‐cell signaling pathways. Altogether, this first report with a potent and selective inhibitor elucidates how MALT1 paracaspase activity integrates several T‐cell activation pathways and indirectly controls gamma‐chain receptor dependent survival, to impact on T‐cell expansion.