Charles Eric Mowbray

Pyrazole NNRTIs 4: Selection of UK-453,061 (lersivirine) as a Development Candidate

We prepared three discreet cohorts of potent non-nucleoside HIV reverse transcriptase inhibitors (NNRTIs) based on the recently reported 3-cyanophenoxypyrazole lead 3. Several of these compounds displayed very promising anti-HIV activity in vitro, safety, pharmacokinetic and pharmaceutical profiles. We describe our analysis and conclusions leading to the selection of alcohol 5 (UK-453,061, lersivirine) for clinical development.

Lersivirine, a nonnucleoside reverse transcriptase inhibitor with activity against drug-resistant human immunodeficiency virus type 1.

ABSTRACT The nonnucleoside reverse transcriptase inhibitors (NNRTIs) are key components of highly active antiretroviral therapy (HAART) for the treatment of human immunodeficiency virus type 1 (HIV-1). A major problem with the first approved NNRTIs was the emergence of mutations in the HIV-1 reverse transcriptase (RT), in particular K103N and Y181C, which led to resistance to the entire class. We adopted an iterative strategy to synthesize and test small molecule inhibitors from a chemical series of pyrazoles against wild-type (wt) RT and the most prevalent NNRTI-resistant mutants. The emerging candidate, lersivirine (UK-453,061), binds the RT enzyme in a novel way (resulting in a unique resistance profile), inhibits over 60% of viruses bearing key RT mutations, with 50% effective concentrations (EC50s) within 10-fold of those for wt viruses, and has excellent selectivity against a range of human targets. Altogether lersivirine is a highly potent and selective NNRTI, with excellent efficacy against NNRTI-resistant viruses.

Novel Indazole Non-Nucleoside Reverse Transcriptase Inhibitors Using Molecular Hybridization Based on Crystallographic Overlays

A major problem associated with non-nucleoside reverse transcriptase inhibitors (NNRTIs) for the treatment of HIV is their lack of resilience to mutations in the reverse transcriptase (RT) enzyme. Using structural overlays of the known inhibitors efavirenz and capravirine complexed in RT as a starting point, and structure-based drug design techniques, we have created a novel series of indazole NNRTIs that possess excellent metabolic stability and mutant resilience.

Challenges of drug discovery in novel target space. The Discovery and Evaluation of PF-3893787: A Novel Histamine H4 Receptor Antagonist

We describe the development of novel benzimidazoles as small molecule histamine H4 receptor (H4R) antagonists and their profiling in rat early toxicity studies. The discovery and optimisation of a second series of pyrimidine based antagonists is then described culminating in the identification of the clinical development candidate 13 (PF-3893787). The pre-clinical profile of 13 (PF-3893787) is presented including the development of a translatable biomarker. Our pragmatic approach to target selection, safety assessment, and testing for efficacy faced numerous challenges and we share a number of lessons which the team learned and which will assist us and others in future drug discovery projects.

Pyrazole NNRTIs 1: design and initial optimisation of a novel template.

The design and synthesis of a novel series of non-nucleoside HIV reverse transcriptase inhibitors (NNRTIs) based on a pyrazole template is described. These compounds are active against wild type reverse transcriptase (RT) and retain activity against clinically important mutants.

Pyrazole NNRTIs 3: Optimisation of physicochemical properties

Our efforts to reduce overall lipophilicity and increase ligand-lipophilicity efficiency (LLE) by modification of the 3- and 5-substituents of pyrazole 1, a novel non-nucleoside HIV reverse transcriptase inhibitor (NNRTI) prototype were unsuccessful. In contrast replacement of the substituted benzyl group with corresponding phenylthio or phenoxy groups resulted in marked improvements in potency, ligand efficiency (LE) and LLE.

Novel Amino-pyrazole Ureas with Potent In Vitro and In Vivo Antileishmanial Activity.

Visceral leishmaniasis is a severe parasitic disease that is one of the most neglected tropical diseases. Treatment options are limited, and there is an urgent need for new therapeutic agents. Following an HTS campaign and hit optimization, a novel series of amino-pyrazole ureas has been identified with potent in vitro antileishmanial activity. Furthermore, compound 26 shows high levels of in vivo efficacy (>90%) against Leishmania infantum, thus demonstrating proof of concept for this series.

Small, non-peptide C5a receptor antagonists: Part 1

Starting from 2, several highly potent C5a receptor antagonists were synthesised through alpha-amide substitution. Attempts to increase the polarity of these compounds through the introduction of basic centres or incorporation into weakly basic heterocycles is described.

Synthesis of novel histamine H4 receptor antagonists.

This letter describes the discovery and synthesis of a series of octahydropyrrolo[3,4-c]pyrrole based selective histamine hH4 receptor antagonists. The amidine compound 20 was found to be a potent and selective histamine H4 receptor antagonist with moderate clearance and a high volume of distribution.

Comparison of the Non‐Nucleoside Reverse Transcriptase Inhibitor Lersivirine with its Pyrazole and Imidazole Isomers

Lersivirine is a potent non‐nucleoside reverse transcriptase inhibitor with exceptional mutant resilience. Here, we compare the pharmacological and pharmacokinetic profile of lersivirine with its pyrazole and imidazole isomers and briefly explore the profile of these series. This work establishes lersivirine as the outstanding molecule in this set.