Discovering a new medicine that improves a patient’s quality of life can be one of the most exciting aspects of drug discovery. Bioassays are fundamental in early drug discovery, as they provide essential evidence about the activity and/or potency of a compound against a biological target involved in the disease pathway.
In our previous blog, we offered some key tips on how best to approach bioassay design. Here we provide you with the key components for building the best bioassay for your needs. So, as you search for the next breakthrough drug, following these practical guidelines could help ensure you are at the top of the game.
Considerations for target-based and phenotype-based drug discovery
When building a bioassay, you will have already chosen to go down one of two routes: target-based or phenotype-based drug discovery. But what considerations do you need to make when developing bioassays for each of these approaches?
- Target-based drug discovery (TDD): you need to identify not only the type of target activity you want to measure, but also how your bioassay will measure this. It’s also worth thinking about whether to measure the activity at the end of the experiment (end-point) or throughout the experiment (kinetic readouts throughout).
- Phenotype-based drug discovery (PDD): you need to assess whether the biological readout is directly related to the engagement of the compound with the target, or if it is reporting on a component of the pathway instead. Will you need additional bioassays to increase confidence in the outcomes?
To find out more about these different approaches and how to determine which one best suits your drug development research, why not take a look at our free eBook?
Essential factors for building effective bioassays
When developing the best bioassay for your needs, many practical aspects need to be examined to ensure you are using the right approach for successful drug discovery. Below we outline seven key considerations for building great bioassays.
- Plate format: Choosing the best plate format depends on how many compounds you need to test and the cost of your reagents. Using plates with a higher number of wells will allow you to use smaller volumes of reagents, decreasing the cost and increasing throughput.
- Plate type: Assay plates can be black, white or transparent and each is better for different assay types, depending on the readout methods. For example, white plates are great for luminescence assays, whilst black plates work well for fluorescence assays.
- Final assay volume: Several things need to be considered in relation to assay volume, but essentially this comes down to the availability of your reagents and the final desired concentration of both these and the compound in each well of the plate.
- Assay homogeneity: Homogeneous assays involve fewer steps, are faster to execute and are more reproducible, making them great for high-throughput screening and automation.
- Reagent addition and combination: The volume and concentration of each reagent required in the final assay, along with the order you should add them to the plate, and the dispensing method are all important aspects to be aware of.
- Reagent stability: Factors that might affect reagent stability include temperature, light sources and environmental components such as plastics used throughout the bioassay.
- Compound addition: Compounds are generally dissolved in dimethyl sulfoxide (DMSO) but consider optimum concentrations required for your assay. If this is too concentrated, you may observe solubility issues with the compound.
You can find out more details about these key recommendations here, including different plate formats and types best suited to your bioassay.
Next steps for developing first-rate bioassays
By following these steps, you can build great bioassays that meet your drug discovery needs. Not only will they help you make informed decisions about the best candidates to take through to the next stages of the process, it will increase the chance of your compound successfully becoming a new medicine for patients!
But, remember your bioassay must deliver statistically valid and reproducible data. So, it’s crucial to assess whether your bioassay is fit-for-purpose, otherwise your data will not reliably support your decisions. In our next blog, we look at how you can ensure the reproducibility of your assay using quality controls and assay validation procedures. Download our eBook for your guide to addressing this crucial part of the drug discovery process.