Is your screening campaign stuck? 3 signs that it’s time to look for an alternative biophysical technology
Most labs dedicated to drug discovery — in big pharma, biopharma, or CROs — make it a priority to have an adequate lineup of instruments for their screening campaigns. They decide on what technologies to procure based on several considerations, like how well established the method is, its ability to handle the screening of diverse molecules, and whether it offers sufficient or scalable throughput.
If you work in a drug discovery lab, at some point, you too may realize that the technologies at hand are limiting your ability to tackle all your screening projects. Here are 3 signs that it’s time to start looking for a new technology for your screening campaigns.
1. Challenging screenings are slowing down your progress
If an orthogonal method is not right for your research, you may need a method that can manage a challenging screening, especially if your current method has failed or requires too much assay development and optimization to work properly.
Here are a few examples of challenging screenings and some advice on how to overcome their difficulties
Molecular interactions with slow kinetic rate constants
These interactions are difficult to study with methods that require immobilization and that use fluidics (SPR). Slow kinetic rates typically require long measurement times — a guaranteed bottleneck if you need to screen hundreds or thousands of analytes. Measuring equilibrium dissociation constants in solution is definitely something to consider if you experience this issue.
Difficult to control binary and ternary complexes
The equilibrium conditions needed for binary and ternary interactions to take place — like the ones formed by PROTACs, E3 ligases, and the protein of interest — are difficult to control and can affect the calculation of the cooperativity value. In this instance, you may find success with a method that measures binary and ternary interactions in solution, with easily and carefully controlled equilibrium conditions and a flexible assay design.
Screens with multimeric targets
Large protein complexes and membrane proteins are hard to express in the amounts needed for their characterization. They also often need lipids as stabilizing agents. Ensuring the integrity of these proteins is crucial for successful assay development — and difficult to accomplish when your assay calls for immobilization. Consider a method with low sample consumption that works in solution, where the interaction of protein complex subunits can be carefully controlled
Small molecules or fragment libraries
Here you want to look for a method that measures binding affinities independently of a significant change in mass when binding occurs, like MST or TRIC.
2. You need to validate your results with an orthogonal technology
Thorough characterization of molecular interactions can be challenging due to the complexity of the molecules involved. To provide independent confirmation of the interaction properties, orthogonal biophysical methods — different methods intended to measure similar attributes — are used. In addition, orthogonal methods can extend your understanding of the molecular interactions because they can unlock characteristics that were hidden or not accessible before.
It’s not unusual to discover more binders or find discrepancies in the results obtained from different orthogonal methods. If that’s the case, it’s better to keep hits that weren’t found by all methods because molecules with inconsistent binding data can still be valid hits.
3. Your instruments can’t keep up with your increasing throughput demands
Ideally, you want to work with instruments that accommodate a broad range of throughput. This approach is appealing because you can start working with a few samples during assay development and optimization, and then ramp up the throughput once you are ready to screen a larger number of samples. Some technologies provide neither flexible throughput nor a path to upgrade for higher throughput (ITC comes to mind).
If you are contemplating automation — a common approach to managing higher throughput — consider whether the instrument can be easily integrated into the automated liquid handling solution you have in your lab. The automation specialist in your team will not only appreciate but advocate for such an instrument.
If you find yourself in any of these situations, don’t get frustrated, get Dianthus: whether you need an orthogonal technology, you have to get your challenging screening project back on track, or you want an instrument that will integrate into your existing automation solution.