Jutta Wanner

Activation of the p53 pathway by small-molecule-induced MDM2 and MDMX dimerization

Activation of p53 tumor suppressor by antagonizing its negative regulator murine double minute (MDM)2 has been considered an attractive strategy for cancer therapy and several classes of p53-MDM2 binding inhibitors have been developed. However, these compounds do not inhibit the p53-MDMX interaction, and their effectiveness can be compromised in tumors overexpressing MDMX. Here, we identify small molecules that potently block p53 binding with both MDM2 and MDMX by inhibitor-driven homo- and/or heterodimerization of MDM2 and MDMX proteins. Structural studies revealed that the inhibitors bind into and occlude the p53 pockets of MDM2 and MDMX by inducing the formation of dimeric protein complexes kept together by a dimeric small-molecule core. This mode of action effectively stabilized p53 and activated p53 signaling in cancer cells, leading to cell cycle arrest and apoptosis. Dual MDM2/MDMX antagonists restored p53 apoptotic activity in the presence of high levels of MDMX and may offer a more effective therapeutic modality for MDMX-overexpressing cancers.

Recent advances in malaria drug discovery

This digest covers some of the most relevant progress in malaria drug discovery published between 2010 and 2012. There is an urgent need to develop new antimalarial drugs. Such drugs can target the blood stage of the disease to alleviate the symptoms, the liver stage to prevent relapses, and the transmission stage to protect other humans. The pipeline for the blood stage is becoming robust, but this should not be a source of complacency, as the current therapies set a high standard. Drug discovery efforts directed towards the liver and transmission stages are in their infancy but are receiving increasing attention as targeting these stages could be instrumental in eradicating malaria.

Pyrrolopyrazines as selective spleen tyrosine kinase inhibitors.

We describe the discovery of several pyrrolopyrazines as potent and selective Syk inhibitors and the efforts that eventually led to the desired improvements in physicochemical properties and human whole blood potencies. Ultimately, our mouse model revealed unexpected toxicity that precluded us from further advancing this series.

Rational design of highly selective spleen tyrosine kinase inhibitors.

A novel approach to design selective spleen tyrosine kinase (Syk) inhibitors is described. Inhibition of spleen tyrosine kinase has attracted much attention as a mechanism for the treatment of autoimmune diseases such as asthma, rheumatoid arthritis, and SLE. Fostamatinib, a Syk inhibitor that successfully completed phase II clinical trials, also exhibits some undesirable side effects. More selective Syk inhibitors could offer safer, alternative treatments. Through a systematic evaluation of the kinome, we identified Pro455 and Asn457 in the Syk ATP binding site as a rare combination among sequence aligned kinases and hypothesized that optimizing the interaction between them and a Syk inhibitor molecule would impart high selectivity for Syk over other kinases. We report the structure-guided identification of three series of selective spleen tyrosine kinase inhibitors that support our hypothesis and offer useful guidance to other researchers in the field.

Evaluation of secondary amide replacements in a series of CCR5 antagonists as a means to increase intrinsic membrane permeability. Part 1: Optimization of gem-disubstituted azacycles

Replacement of a secondary amide with an N-acyl or N-sulfonyl gem-disubstituted azacyle in a series of CCR5 antagonists led to the identification of compounds with excellent in vitro HIV antiviral activity and increased intrinsic membrane permeability.

Small Molecule Antagonists of the Chemokine Receptor CCR5

This review will focus on the discovery and clinical development of small molecule antagonists of CCR5 for the treatment of HIV-1/AIDS, as well as for the potential treatment of inflammatory diseases. In particular, we will focus on the specific medicinal chemistry problems that were faced during the discovery of the molecules. We will also describe limited data from clinical development phases focusing on specific issues that arose during the clinical trials. Finally, we will touch on the mechanism of action of CCR5 antagonists.

Evaluation of a 3-amino-8-azabicyclo[3.2.1]octane replacement in the CCR5 antagonist maraviroc.

The bicyclic 5-amino-3-azabicyclo[3.3.0]octanes were shown to be effective replacements for the 3-amino-8-azabicyclo[3.2.1]octane found in the CCR5 antagonist maraviroc.

Novel hexahydropyrrolo[3,4-c]pyrrole CCR5 antagonists.

Starting with a high-throughput screening lead, a novel series of CCR5 antagonists was developed utilizing an information-based approach. Improvement of pharmacokinetic properties for the series was pursued by SAR exploration of the lead template. The synthesis, SAR and biological profiles of the series are described.

Evaluation of a 4-aminopiperidine replacement in several series of CCR5 antagonists.

The bicyclic 5-amino-3-azabicyclo[3.3.0]octanes were shown to be effective replacements for the conformationally restricted 4-aminopiperidine ring found in several series of CCR5 antagonists.

Evaluation of amide replacements in CCR5 antagonists as a means to increase intrinsic permeability. Part 2: SAR optimization and pharmacokinetic profile of a homologous azacyle series.

Replacement of a secondary amide with a piperidine or azetidine moiety in a series of CCR5 antagonists led to the discovery of compounds with increased intrinsic permeability. This effort led to the identification of a potent CCR5 antagonist which exhibited an improved in vivo pharmacokinetic profile.