DNA-Encoded Library and Drug Discovery

Methods like high-throughput screening (HTS), fragment-based drug discovery, and computer-assisted drug discovery are often used in early drug hit identification. The molecular diversity and quality of the screening collection can be crucial to the discovery of compounds that have desirable pharmacological properties. However, due to its costs, a practical upper limit on the number of compounds was set during screening, and therefore the molecular diversity that can be screened is also limited. In such case, biological selection methods related to the expression and screening of peptides and proteins, such as DNA-encoded library, could be a very good choice.

On December 9, 2016, Robert A. and other researchers published a paper titled "DNA-encoded chemistry: enabling the deeper sampling of chemical space" in Nature Reviews Drug Discovery, which has led to extensive attention worldwide on the R&D of new drugs.

In the article, the author elaborates on the convenience and advantages of the DNA-encoding compound library (DEL) for the faster and broader extension of the chemical space of drug-like molecules beyond traditional small molecule synthesis chemistry. Because most of the drug molecules currently have the characteristics of organic compounds, the chemical space and related models mentioned in this paper all refer to the chemical space of organic small molecules.

Introduction to various chemical space databases

In fact, as early as 1875, Cayley had begun to notice the concept of chemical space and made many attempts to describe the chemical space. With the development of science and technology and the vigorous development of drug research in recent decades, many domestic and foreign scientists have done very important work in expanding chemical space and increasing the diversity of drug molecules. Martin D. Burke and other researchers are advocates of "Diversity-Oriented Synthesis", which is clearly stated in the article "A Planning Strategy for Diversity-Oriented Synthesis", and the method of diversity-directed synthesis can be elaborated to more deeply expand the drug-like molecules more efficiently. Covering more chemical space will bring more possibilities for drug-forming molecules. However, how to rapidly synthesize more types of small molecule compounds and screen for drug activity will become a greater challenge.

Then DNA coding compound library comes to rescue, which can help solve the above problems well. In 1992, Brenner, S. and Lerner, R. A., two scientists propose the concept of DNA coded library  for the first time in the "Encoded combinatorial chemistry", as well as other elements like the theoretical basis and experimental methods from the establishment of DNA coded library to the final compound screening.

At present, DNA-encoded libraries have been widely used in the synthesis and screening of seed compounds in the field of new drug research and development, and have played a very important role. The DNA-encoding compound library is capable of simultaneously synthesizing small organic compounds and performing drugs in a split-pool manner based on a variety of DNA-compatible chemical reactions (DEC) and a large building block reagent library, as well as a special compound encoding-decoding method. The activity screening not only increases the synthesis flux by the difference of the order of magnitude compared with the traditional synthesis method, but also greatly shortens the synthesis cycle, which is also more efficient for further expanding and covering the chemical space of drug-like molecules. It can be more specifically referred to as activity-based libraries. This has made it possible to increase the number of new drugs, significantly shorten the drug development cycle, and reduce R&D costs.

According to the data presented by Robert A. in the article, drug discovery companies and other research institutions at home and abroad, have screened a large number of active target compounds based on DNA-encoded compound libraries, covering small molecule active compounds and macrocyclic active compounds. IC50 has a minimum of 0.3nmol. For example, GSK, X-Chem, Ensemble, etc. have received wide attention from the industry for their DNA-encoded library.