Why is High-Throughput Discovery Important? An overview of the impact of HT on drug discovery.
Legend. High-throughput discovery uses advancements in miniaturization, automation and robotics to screen thousands of genes, conditions and/or compounds. Because of high-throughput screening, scientists have been able to screen 10,000-100,000 compounds per day. This has allowed for a quicker and more efficient method of drug discovery and proves the importance of this technology. High-throughput discovery has revolutionized the world of science and has resulted in multiple discoveries of new drugs and novel developmental phenotypes (1).
Introduction
High-throughput screening (HTS) is the ability to screen 10,000-100,000 compounds per day. This amplitude of automation allows for scientists to create vast libraries of compounds, which can be used in pharmaceutical and biotechnology settings. These high-throughput approaches have enabled drug discovery. High-throughput discovery uses fully automated robotic systems to test large numbers of compounds daily, in search of hits or leads. Hits are compounds with desirable effects. Lead-like properties of compounds include size, shape and solubility that make these compounds ideal starting points or precursors to drugs (1). High-throughput discovery has allowed scientists to accelerate drug discovery through technology such as liquid handling devices, robotics, data processing and control software. Some examples of equipment used in high-throughput discovery include Opentrons OT-2, Biotek plate readers, epMotion 5075 TC, and 96-well plates (1). However, it is important to understand that drug development does not happen solely from HTS. The primary role of HTS is to identify leads and a starting point for further steps in drug discovery. Examples of other steps that must also happen are evaluation of toxicity and bioavailability (2).
High-throughput screening originated from the company called Pfizer, which used HTS to screen natural products in 1986. Pfizer did this by substituting fermentation broths with dimethyl sulphoxide solutions of synthetic compounds and then using 96-well plates with reduced assay volumes of 50-100 μl. The concept of HTS was initiated by the Molecular Genetics Group project that wanted to exploit R DNA to create novel antibiotics or improve antibiotic production (3). Their original approach proved too slow and not able to maintain routine discovery support so they decided to take a different approach that would increase screening capacity and efficiency. Thus, HTS was implemented.
Advantages and Disadvantages
Some of the advantages to high-throughput discovery is that it is able to quickly develop pharmaceutical drugs. This is due to the ability to screen libraries of thousands of compounds through HTS. Compared to other methods, HTS is able to more efficiently screen compounds and locate targets and leads. Traditional screening allowed for 20-50 compounds a week while high-throughput screening allowed for 10,000-100,000 compounds per day.
Disadvantages of high-throughput discovery include the screening expense, cost of machines, false negatives, false positives and need for a broad interdisciplinary knowledgebase. There are many costs that go into high-throughput discovery. Costs, such as assay reagents, microplates, pipette tip boxes, robots, laboratory space and infrastructure investments, are reasons smaller labs and companies are not able to use high-throughput methods. An assay to completely screen a large compound library may amount to over $300,000 (4). In addition to this, HTS approaches suffer from errors such as false positives and false negatives. False positives are compounds identified as hits but are not actually active. False negatives are mistakes of not identifying true active compounds as through statistical processes. To successfully perform high-throughput methods, a broad interdisciplinary knowledgebase is needed. It often requires collaboration between many disciplines such as chemical engineers, chemists, biologists, medicinal chemists, and biomanufacturers (1).
Low-throughput Screening vs. High-throughput Screening
Low-throughput screening is also referred to traditional screening. This way of screening often uses just human power instead of robotics. It uses a single tube with a large assay volume of about 1 ml. The assay components are added one at a time which makes the assays slow and laborious. This method is able to screen 20-50 compounds per week (3). The disadvantages of low-throughput screening are it is only able to screen a limited number of compounds and it is laborious. However, it is cost efficient and readily available to smaller companies or labs.
High-throughput screening is able to use human power, such as multi-channel pipettes but mostly focuses on automated robots. This method of screening uses 96-well assays with a small assay volume of 50-100 μl. The assay components are added simultaneously through automated machinery such as liquid handlers. The mechanical action is 1 to 96 ratios instead of the 1 to 1 ratio from low-throughput screening (3). HTS automation and miniaturization allows for assays to be fast and efficient, and scientists are able to screen 10,000-100,000 compounds daily (1). However, this high-throughput method costs a lot to run and maintain. In addition, the machinery is expensive to purchase. A great amount of knowledge is needed to operate the machinery and perform HTS methods. This method would not be ideal for start up labs or smaller companies due to the complexity and cost.
Impact of High-throughput Discovery on Drug Discovery
High-throughput discovery has had a major impact on drug development and discovery. As discussed in this overview, high-throughput discovery uses high-throughput methods, such as HTS, that are characterized by miniaturization, automation, replication, and validation. With these methods, several libraries composed of thousands of compounds can be screened efficiently for targets and leads. Because of this, these methods allow for fast and efficient drug discovery and development. Although it is not the only step of drug discovery, it serves an important part.
Even with all the disadvantages of high-throughput technologies, it has been very impactful on modern pharmaceutical research and development. In an analysis of 58 drugs that were approved between 1991 and 2008, 19 of those drugs were attributed to HTS. Some examples of approved drugs with origins in HTS hits include Gefitinib, Erlotinib, Sorafenib, Tipranavir, Maraviroc, Etravirine, and Eltrombopag (5). These drugs were made possible through HTS screening of libraries comprised of thousands of compounds and the location of at least one hit. From there, scientists can use the hit as a starting point for more screening.
In recent times, high-throughput technologies are being used for COVID-19 diagnosis and vaccine evaluation. The gold standard for determining antibody efficacy has been virus neutralization. High-throughput assays are being used to measure SARS-CoV-2 neutralizing antibodies. This is needed for serodiagnosis, convalescent plasma therapy and vaccine development (6). A fluorescence-based high-throughput neutralization assay is used specifically to measure COVID-19 neutralizing antibodies without cross reacting with patient specimens with other viral, bacterial or parasitic infections (6).
Without high-throughput methods, scientists would not have been able to successfully produce such pharmaceutical drugs in such timely manner. The pharmaceutical and biotechnological fields would not have revolutionized. High-throughput discovery has made it possible for rapid drug discovery and efficient drug development.
References
- NCSU Biotechnology Program. (Spring 2021). Module 1: What is high-throughput discovery science? BIT 479/579 High-throughput Discovery. 1 May 2021.
- Pusterla, T. (2019). High-throughput screening (HTS). BMG Labtech. https://www.bmglabtech.com/high-throughput-screening/
- Pereira, D. A. & Williams, J. A. Origin and evolution of high throughput screening. Br J Pharmacol 152, 53-61 (2007).
- Martis, E. A., Radhakrishnan, R., & Badve, R. R. High-Throughput Screening: The Hits and Leads of Drug Discovery- An Overview. Journal of Applied Pharmaceutical Science 1, 2-10 (2011).
- Macarron, R., Banks, M., Bojanic, D. et al. Impact of high-throughput screening in biomedical research. Nat Rev Drug Discov 10, 188–195 (2011).
- Muruato, A.E., Fontes-Garfias, C.R., Ren, P. et al.A high-throughput neutralizing antibody assay for COVID-19 diagnosis and vaccine evaluation. Nat Commun 11, 4059 (2020).
- Bartlett, M. High-throughput screening robots. Photograph.
- World of Chemicals. High-throughput screening assays. Photograph.