Category: Chemical Biology
X-Chem, in collaboration with AstraZeneca, is interested in identifying inhibitors of a tyrosine receptor kinase implicated in diseases such as gastrointestinal stromal tumors (GISTs). X-Chem previously identified selective kinase inhibitors by simultaneously interrogating >100 billion library members in multiplexed selection conditions. In this approach all library members are evaluated in parallel for binding to a range of target isoforms including under varied solution conditions. Retained library members are amplified and encoded chemical information is extracted using deep-sequencing technology via hundreds of millions of independent sequence reads. Our proprietary informatics platform identifies enriched clusters of structurally related building block combinations and determines their enrichment profile across all selection conditions. Exemplar compounds with desirable profiles and physiochemical properties are then synthesized and assessed for activity and selectivity. DNA-Encoded Library Screening and Informatics Platform (DEXTM Technology) project success is highly driven by the quality of reagents, and this is especially important when comparing isoforms. Proteins in selection need to be a single form to effectively drive binding interactions, and quality is assessed by size-exclusion chromatography, dynamic light scattering, and thermal melt. Additionally, proteins in selection are confirmed to maintain biochemical activity while immobilized in the course of selection. Because the proteins are assessed for quality and small molecule accessibility, we are able to more accurately analyze DNA tag sequencing data for statistically-relevant binding interactions. These high quality selection data enables identification of small molecule binders with desired mode of action. In this study, X-Chem evaluated wild-type kinase, different mutants, and closely related kinases for quality, and then in selection to identify selective kinase inhibitors. The project successfully in-licensed multiple novel chemical series with desired selectivity profiles at AstraZeneca.
Diana Gikunju– Senior Research Scientist, X-Chem Inc, Waltham, MA
Senior Research Scientist
Diana is originally from Kenya and received her BA in Biochemistry from Clark University and her MS in Biology from Brown University. At Pfizer, she developed screening technologies across a broad spectrum of disease areas in high throughput screening. She later transitioned to focus on developing new assays and implemented new technologies with a focus on protein and lipid kinases to support drug discovery programs and address key causes of drug candidate attrition. She also developed a cell-based dual luciferase switch-on platform to access efficacy of oligonucleotides for gene knockdown in specific tissue types. Since joining X-Chem in 2011, she has supported and led collaborative projects resulting in discovery of multiple lead compounds to a variety of therapeutic targets. She also has applied both in vitro and biophysical assays to determine binding moiety of compounds with an aim of enabling programs in collaborative efforts.