CONA-HTS: Confocal Nanoscanning - Bead Picking - AIDA Technology. A Methodology for Drug Discovery with Orphan Molecular Targets and Combinatorial Chemistry on the Solid Surface

Abstract

In pharmaceutical industry high-throughput screening (HTS) has become one of the key elements of the drug discovery process. High-throughput screens have been successfully carried out for important drug targets such as receptors, enzymes, nucleic acids and others. This trend will continue since the integration of genomics- or proteomics-based drug discovery approaches will lead to an exceedingly large number of targets that have to be tested. Major challenges to meet in high-throughput (HTS) screening technology include speed, cost and mechanistic content. Parallelization and miniaturization are important concepts which are pursued nowadays to satisfy these needs. However, miniaturization in HTS involves detection and characterization of sparse quantities of bioactive molecules. In particular, novel methodologies based on ultra-sensitive detection of laser-induced fluorescence and laser spectroscopy with single molecule sensitivity allow for identification of bioactive molecules and their discrimination against a large number of inactive compounds. Another challenge is the handling of the huge numbers of compounds to be screened. In this context, screening of combinatorial libraries is attractive because these one-bead-one-compound libraries are comparatively inexpensive to produce and can be conveniently handled and stored in small volumes. The CONA-HTS (confocal nanoscanning / bead picking - AIDA-technology) was developed by Novartis and EvotecOAI as a novel high throughput - low hit-rate process which allows to detect binding between fluorescently tagged biomolecules in solution and compounds on the solid surface. The binding reaction on the solid surface in which on-bead fluorescence (ring) intensity is directly proportional to on-bead affinity can either be specific or unspecific. The binding specificity is therefore checked immediately after selecting a bead by cleavage of the compound from the solid surface and determination of a dissociation constant to the unlabeled target protein using the Novartis proprietary AIDA-dye tagging system. In parallel, the structure is decoded by mass spectrometry and after re-synthesis, on- and off-bead confirmation, the potential hit compounds are tested with and without AIDA-tag for their in-vitro and cellular activity. Current deliveries of CONA-HTS include: • new active hit structures: binders, inhibitors in-vitro / in-vivo, • structure-activity relationship of substituents of cyclic andacyclic inhibitors, • novel class of binders to known pockets, new hydrogenbonds, defined by crystal structures, • two or multiple binding site inhibitors in protein-proteininteractions, • new RNA binding structures, • suggestions and answers to scientific questions.