Novel trends in high-throughput screening

Lead discovery by high-throughput screening (HTS) has evolved into a mature scientific discipline in modern drug discovery since its beginning about 10–15 years ago. Owing to the strong efforts in automation and miniaturization, even relatively large compound collections of over one million compounds or more can be screened against a large number of biological targets in relatively short time and at relatively low cost compared to the efforts of just 5 or 10 years ago. This was only possible with the concomitant development of high-quality readout technologies for highly miniaturized screening. Whereas most of the conventional drug targets can be approached via current HTS-readout technologies, the challenge goes toward the hitherto non-tractable families of drug targets. Future trends will focus strongly toward these novel target classes such as ion channels, transporters, protein–protein interactions, among many others. It will be essential to make proper readout technologies and adequate chemical libraries available for these target classes. Chemical libraries derived from natural products, but also derived from combinatorial chemistry and automated synthesis will be a key prerequisite for success in the field, as long as enough diversity and drug-like properties are included in these chemical libraries 25]. The proper readout technologies for screening of large chemical libraries have seen strong advances in recent years ^{2], 7] and 22••]}], nevertheless none of these technologies is void of artifacts, in particular artifacts derived from the inherent physical nature of chemical compounds in aqueous buffer 11^••]. We therefore propose that future lead discovery should pay more attention toward unambiguous identification of these compound related artifacts and toward efficient removal of these false-positive compounds from the HTS hit-lists. We strongly recommend the use of biophysical and enzymological studies in the HTS hit-list follow-up phase (‘hit validation’) in order to deliver information of the highest possible quality for subsequent hit-to-lead studies. Finally, the science and art of HTS has evolved in various phases from its beginning in the early 1990s toward today's state-of-the-art operation in lead discovery. During these 15 years, one can distinguish three phases (‘generations’) of HTS operations: during the first phase, HTS has been just the same as laboratory screening, albeit at much larger capacity; in the second phase (‘second generation HTS’), HTS has evolved toward more sophisticated assay development/adaptation, more toward dedicated tool production, but also more toward counter-screening and hit-list follow-up; in the current phase (‘third generation HTS’) we see much more flexibility with regards to the applied processes for lead discovery, a stronger focus on quality and validation of the obtained results and a better awareness for choosing a proper lead finding strategy in a target-by-target specific manner.Taken together, we can conclude that better flexibility and creativity, more quality and the use of project-related, tailor-made lead finding strategies in the discovery process will become the key drivers for the successful application of high-throughput screening in the Pharmaceutical, Biotech, and Academic drug discovery programs of the future.

References and recommended reading

Papers of particular interest, published within the period of review, have been highlighted as:

• of special interest

•• of outstanding interest

Acknowledgements

We are very grateful to our colleagues at NIBR (Novartis Institutes for Biomedical Research), Center of Proteomic Chemistry, Basel & Cambridge, who have contributed to the successful implementation and application of the highly miniaturized assay development and screening technologies for lead discovery research at Novartis Pharmaceuticals.