Ion channel drug discovery with leading-edge facilities and a strategic approach!~Drug discovery ability to overcome challenges~

3Delivering high-quality and high-efficiency screening with professional skills and leading-edge technology

First, please tell me about manual patch clamping with regards to the electrophysiological approach.

Seki:Manual patch clamping is the gold-standard method for ion channel research, and the most common method of that is a whole-cell patch-clamp method. Homogeneous data collection is so difficult with the manual patch clamp method, and it will take roughly five years to achieve consistent measurement of various ion channels.

It requires such high skills!

Seki:Yes, learning the skills necessary for the manual patch clamp method is hard, but the electrophysiological approach is essential for screening in ion channel drug discovery. The automated patch clamp method doesn’t require such artisan skill as the manual patch clamp method, and its high-capacity throughput is attractive. However, a high level of expertise is still necessary even for the automated patch clamp method, and evaluation method construction and data interpretation also require a wealth of experience and knowhow.

You mentioned enhancing HTS with SyncroPatch 384PE, how do you characterize it?

Seki:SyncroPatch 384PE is the latest patch clamping system to be compatible with a 384-well plate and to enable screening with high-throughput. There were problems with measurements using fluorescent dyes, because controlling cell membrane potential is difficult. To find compounds with the required mode of action, electophysiological assays are required. SyncroPatch 384PE is an automated patch clamp system to bridge the gap between primary and secondary screening. It provides an optimum pulse protocol for evaluation. Also, another significant advantage is that it enables us to acquire hit compounds that are more suitable to our client’s needs. I believe that evaluation system construction and HTS can be accomplished within a year in the current service system.

Are there any other points you pay attention to in the electrophysiologic assay system?

Hirano:I handle the cells used for assays with close attention. Since an electrophysiologic assay has delicate processes, it may be referred to as the assay system largely influenced by cell conditions. That’s why, at Axcelead DDP, researchers with extensive experience of the electrophysiologic assay are also responsible for the preservation and passage of cells.

How do you characterize the libraries used for screening?

Hibino:A library is also important. The compound libraries in Axcelead are very satisfying. We can offer a library suitable for MOA supposed to be a client-requesting target by carefully selecting from over 1.5 million diverse and high-quality compounds. Furthermore, virtual screening using in silico drug discovery technology is also available in addition to random screening.

What type of data do you provide to clients?

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Hibino:In addition to hit compounds, high-value added information, which is Axcelead DDP’s strength, is provided. Specifically, past evaluation data (e.g., cellular cytotoxicity information and compound annotation information), and comments from the chemistry division and medicinal chemists about the structural features of representative clusters, will be reported too.

4Pursuing the realization of “drug discovery” by transforming the dots into lines

What challenges does the current evaluation method have?

Hirano:The challenge is that the function of target ion channels and the environment in which ion channels are actually functioning (information on localization and molecular complexity) remain unclear. In the usual screening, CHO-K1 or HEK293 cells that are forced to express ion channels are often used. However, forcing ion channel expression may be insufficient in evaluating ion channel functions accurately. In addition, although ion channels generally function as a complex of multiple proteins (subunits), screening often evaluates only for the key subunit (a-subunit) expression. However, considering necessary subunit and molecular complex varying with the types of ion channels, the current system might miss compounds. Therefore, for the future, I am thinking of using the cells obtained from a living body, or derived from iPS cells, for the construction of an evaluation method that reflects functions closer to those of physiologically expressed ion channels.

Future development seems exciting! Finally, tell me the distinctive points of AxceleadDDP’s contribution to clients’ drug discovery.

Hibino:In the case of HTS targeting ion channels, strategies in which target ion channels are simply activated or inhibited are often found to be insufficient. As I mentioned earlier, ion channels especially are targets that easily lead to critical adverse reactions. There are many points to be considered and devised in planning an HTS strategy. For example, are there any channels resulting in adverse reactions with poor selectivity? Can adverse reactions based on targets be prevented by means of differentiating activation and inhibition manner? We would like to propose a screening strategy with consideration of post-hit issues and countermeasures on the basis of our long experience of drug discovery research.

When facilitating the drug discovery targeting ion channels, evaluations other than ion channel functions are also important. Because Axcelead DDP has been conducting hundreds of HTS for a variety of drug discovery targets other than ion channels, we are capable of hit compound exploration with a screening strategy in combination with a wide variety of examinations, including structure activity relationship based on structural information and phenotype analysis.

Furthermore, we also have the functions and professionals necessary for drug discovery in the post-HTS process, including hit expansion, compound optimization, in vivo evaluation of compounds, and translational research. Therefore, by not providing a single assay, but connecting the assays and planning the best strategy, we will provide support for achieving clients’ goals in the shortest time possible.

Hibino-san, Seki-san, Hirano-san, thank you very much for your time!

Summary for today

  • Because biology and the tools and evaluation methods for drug discovery are evolving, the potential of ion channel drug discovery is expected to expand further.
  • Specialists who have been involved in actual drug discovery settings, and have been accumulating experience through a trial-and-error process, propose the best screening strategy with consideration of challenges and tricks unique to ion channel targeted drugs.
  • The latest technology, such as SyncroPatch 384PE, and evaluation methods necessary for drug discovery, other than ion channel assays, are strategically incorporated to support achievement of the client’s goal more efficiently.