Patrick Stephen Johnson

Design of Potent and Selective Inhibitors to Overcome Clinical Anaplastic Lymphoma Kinase Mutations Resistant to Crizotinib.

Crizotinib (1), an anaplastic lymphoma kinase (ALK) receptor tyrosine kinase inhibitor approved by the U.S. Food and Drug Administration in 2011, is efficacious in ALK and ROS positive patients. Under pressure of crizotinib treatment, point mutations arise in the kinase domain of ALK, resulting in resistance and progressive disease. The successful application of both structure-based and lipophilic-efficiency-focused drug design resulted in aminopyridine 8e, which was potent across a broad panel of engineered ALK mutant cell lines and showed suitable preclinical pharmacokinetics and robust tumor growth inhibition in a crizotinib-resistant cell line (H3122-L1196M).

The development of non-steroidal dual inhibitors of both human 5α-reductase isozymes

Abstract The design, synthesis and biological properties of homochiral non-steroidal inhibitors of both isozymes of human 5α-reductase are described. The o-hydroxy aniline moiety of the initial lead (1) can be replaced by a 3-acyl indole isostere, whilst the minimum energy conformation of the benzyl ether in the potent inhibitor (3) is mimicked by the conformationally locked benzodioxolane system in the potent non-steroidal inhibitor (7). Pharmacokinetics and oral efficacy in a rat model of BPH are presented for (3) and (7).

Designing rapid onset selective serotonin re-uptake inhibitors. 2: structure-activity relationships of substituted (aryl)benzylamines.

A series of substituted benzylamines 2-48 were prepared as part of a strategy to identify structurally differentiated and synthetically more accessible selective serotonin reuptake inhibitors, relative to clinical candidate 1. In particular, 44 and 48; demonstrated low nanomolar potency and good selectivity, in a structurally simplified template and, in vivo, very low Vdu, significantly lower than l, and a more rapid T(max), consistent with our clinical objectives.

Discovery of PF-184563, a potent and selective V1a antagonist for the treatment of dysmenorrhoea. The influence of compound flexibility on microsomal stability

The V1a receptor has emerged as an attractive target for a range of indications including Raynauds disease and dysmenorrhoea. As part of an effort to discover a new class of orally active V1a antagonist, we optimised a highly lipophilic, metabolically unstable lead into a range of potent, selective and metabolically stable V1a antagonists. In this communication, we demonstrate the series-dependent effect of limiting the number of rotatable bonds in order to decrease Cytochrome P450-mediated metabolism. This effort culminated in the discovery of PF-184563, a novel, selective V1a antagonist with excellent in vitro and in vivo properties.

Optimisation of a pyrazole series of progesterone antagonists; Part 1.

The design and synthesis of a novel series of non-steroidal progesterone receptor antagonists is described. Ligand-lipophilicity efficiency (LLE) was used in the selection of a prototype agent for in vivo pharmacology studies.

Designing rapid onset selective serotonin re-uptake inhibitors. Part 3: Site-directed metabolism as a strategy to avoid active circulating metabolites: Structure–activity relationships of (thioalkyl)phenoxy benzylamines

A series of thio-alkyl containing diphenylethers were designed and evaluated, as a strategy to competitively direct metabolism away from unwanted amine N-demethylation and deliver a pharmacologically inactive S-oxide metabolite. Overall, sulfonamide 20 was found to possess the best balance of target pharmacology, pharmacokinetics and metabolism profile.

Improved Method for the Preparation of Oxadiazoles from Diacyl Hydrazines

N-methylimidazole (NMI) is used as the base in the triflic anhydride (Tf2O)–mediated formation of oxadiazoles from diacyl hydrazines. This reagent is superior to pyridine-derived bases in terms of cost and reaction profile.