Identification and Optimization of Novel Small c-Abl Kinase Activators Using Fragment and HTS Methodologies.

Abelson kinase (c-Abl) is a ubiquitously expressed, nonreceptor tyrosine kinase which plays a key role in cell differentiation and survival. It was hypothesized that transient activation of c-Abl kinase via displacement of the N-terminal autoinhibitory "myristoyl latch", may lead to an increased hematopoietic stem cell differentiation. This would increase the numbers of circulating neutrophils and so be an effective treatment for chemotherapy-induced neutropenia. This paper describes the discovery and optimization of a thiazole series of novel small molecule c-Abl activators, initially identified by a high throughput screening. Subsequently, a scaffold-hop, which exploited the improved physicochemical properties of a dihydropyrazole analogue, identified through fragment screening, delivered potent, soluble, cell-active c-Abl activators, which demonstrated the intracellular activation of c-Abl in vivo.

Practical purification of hydrophilic fragments and lead/drug-like molecules by reverse phase flash chromatography: tips, tricks and contemporary developments.

Practical purifications of hydrophilic fragments and lead/drug-like molecules are reviewed, focussing particularly on the rational use of C-18 reverse phase flash chromatography by exploiting the relationship between retention time and distribution coefficients. Logical process changes have been implemented to suit the particular physical properties of individual molecules, notably, various combinations of dry loading, methanol-buffer gradients, pH control and columns designed for 100% aqueous elution. These have been used to great effect; facilitating effective, predictable and scalable purifications of fragments and lead/drug-like molecules, for which other techniques sometimes fail.