Biomedical subjects

Mario Varasi

Publications and source records attributed to Mario Varasi.

6 recordsLinked to original sources

PubMed2005

3-Aminopyrazole inhibitors of CDK2/cyclin A as antitumor agents. 2. Lead optimization.

Inhibitors of cyclin-dependent kinases (CDK) such as CDK2/cyclin A-E are currently undergoing clinical trials to verify their potential as new anticancer agents. In a previous article we described the lead discovery process of a 3-aminopyrazole class of CDK2/cyclin A-E inhibitors. The endpoint of this process was PNU-292137, a compound endowed with in vivo antitumor activity in a mouse tumor xenograft model. We optimized this lead compound to improve some physicochemical properties, notably solubility and plasma protein binding. This lead optimization process brought us to the discovery of (2S)-N-(5-cyclopropyl-1H-pyrazol-3-yl)-2-[4-(2-oxo-1-pyrrolidinyl)phenyl]propanamide (PHA-533533, 13), a compound with a balanced activity vs druglike profile. Compound 13 inhibited CDK2/cyclin A with a K(i) of 31 nM, counteracting tumor cell proliferation of different cell lines with an IC(50) in the submicromolar range. Solubility was improved more than 10 times over the starting lead, while plasma protein binding was decreased from 99% to 74%. With exploitation of this globally enhanced in vitro profile, 13 was more active than PNU-292137 in vivo in the A2780 xenograft model showing a tumor growth inhibition of 70%. Proof of mechanism of action was obtained in vivo by immunohistochemical analysis of tumor slices of 13-treated vs untreated animals.

Animals↗

PubMed2005

Potent and selective Aurora inhibitors identified by the expansion of a novel scaffold for protein kinase inhibition.

Potent and selective Aurora kinase inhibitors were identified from the combinatorial expansion of the 1,4,5,6-tetrahydropyrrolo[3,4-c]pyrazole bi-cycle, a novel and versatile scaffold designed to target the ATP pocket of protein kinases. The most potent compound reported in this study had an IC(50) of 0.027 microM in the enzymatic assay for Aur-A inhibition and IC(50)s between 0.05 microM and 0.5 microM for the inhibition of proliferation of different tumor cell lines.

Adenosine Triphosphate↗

PubMed2004

3-Aminopyrazole inhibitors of CDK2/cyclin A as antitumor agents. 1. Lead finding.

Abnormal proliferation mediated by disruption of the normal cell cycle mechanisms is a hallmark of virtually all cancer cells. Compounds targeting complexes between cyclin-dependent kinases (CDK) and cyclins, such as CDK2/cyclin A and CDK2/cyclin E, and inhibiting their kinase activity are regarded as promising antitumor agents to complement the existing therapies. From a high-throughput screening effort, we identified a new class of CDK2/cyclin A/E inhibitors. The hit-to-lead expansion of this class is described. X-ray crystallographic data of early compounds in this series, as well as in vitro testing funneled for rapidly achieving in vivo efficacy, led to a nanomolar inhibitor of CDK2/cyclin A (N-(5-cyclopropyl-1H-pyrazol-3-yl)-2-(2-naphthyl)acetamide (41), PNU-292137, IC50 = 37 nM) with in vivo antitumor activity (TGI > 50%) in a mouse xenograft model at a dose devoid of toxic effects.

Acetamides↗

PubMed2004

Solid-phase synthesis of a small library of 3-phenylthio-3-nicotinyl propionic acid derivatives acting as antagonists of the integrin alphaVbeta3.

We describe the synthesis of a series of low molecular weight inhibitors of the alphavbeta3 integrin obtained by modifying a high-throughput screening hit with micromolar activity. A solid phase synthesis to prepare 3-phenylthio-3-nicotinyl propionic acid derivatives, exemplified by 13c, was set up. Compounds with nanomolar activity in the biochemical assay and able to efficiently inhibit cell adhesion mediated by vitronectin have been obtained.

Cell Adhesion↗

PubMed2003

Modulation of the kynurine pathway of tryptophan metabolism in search for neuroprotective agents. Focus on kynurenine-3-hydroxylase.

A novel potent and selective kynurenine-3-hydroxylase inhibitor is descibed along a preliminary evaluation in a in vivo gerbil model of its ability to increase the kynurenine and kynurenic acid concentration in both plasma and brain. These data support the notion that kynurenine-3-hydroxylase inhibitors may have a sustained therapeutic potential in those diseases characterized by unbalance in the QUIN/KYNA branches of the kynurenine pathway.

Animals↗

PubMed2002

High-throughput NMR-based screening with competition binding experiments.

The Achilles heel of ligand-based NMR screening methods is their failure to detect high-affinity ligands and molecules that bind covalently to the receptor. We have developed a novel approach for performing high-throughput screening with NMR spectroscopy that overcomes this limitation. The method also permits detection of potential high-affinity molecules that are only marginally soluble, thus significantly enlarging the diversity of compounds amenable to NMR screening. The techniques developed utilize transverse and/or selective longitudinal relaxation parameters in combination with competition binding experiments. Mathematical expressions are derived for proper setup of the NMR experiments and for extracting an approximate value of the binding constant for the identified ligand from a single-point measurement. With this approach it is possible to screen thousands of compounds in a short period of time against protein or DNA and RNA fragments. The methodology can also be applied for screening plant and fungi extracts.

Binding, Competitive↗