Hit Identification
Hit identification represents one of the crucial early stages in the process of small molecule drug discovery, setting the groundwork for subsequent development efforts and significantly influencing the trajectory of a drug candidate’s journey towards clinical application. The gradually increasing investments required to drive candidate compounds along the “R&D value chain” and the fact that large-scale discovery experiments in most cases are performed only once emphasize the relevance of this early project step.
Building a strong hit identification process not only prevents investing into the wrong compounds, but speeds up the progress by early selection of the right hits with the desired properties to deliver quality drug candidates.
Hit identification is not a commodity. On the contrary: “starting your discovery project right” constitutes the best strategy to safeguard your investment.
Quality and flexibility are the main drivers of hit discovery programs at Axxam:
- Clients can access our assay development services, select one of our ready-to-use assays or transfer their own assays to us.
- We carry out hit discovery programs using either compound collections available at Axxam or our clients’ preferred libraries, which are handled securely at our facility.
- State-of-the-art laboratory automation platforms allow us performing High-Throughput Screening (HTS) using either 384-well (40 μl) or 1536-well (5-10 μl) microplates. The integration of multi-modality plate readers, liquid handling devices and robotic plate handling enable the realization of a large spectrum of diverse assay formats.
Besides small molecules, we also offer screenings on chemical mixtures, natural product extracts, oligonucleotides, and antibodies.
Identify qualified hits
In small molecule drug discovery, chance is one driver of hit identification in High-Throughput Screening. However, it is wrong to reduce the process to chance only. Louis Pasteur’s famous “chance favors the prepared mind” most appropriately captures the notion that the purposeful design of all elements of the HTS experiment has equal weight: a suitable screening assay, combining sensitivity and robustness; a well thought through screening cascade to discriminate specific hits from unwanted by-catch; and a compound collection assembled based on a multitude of medicinal chemistry quality criteria and a smart coverage of chemical space.
Assays for primary screening need to comply to the highest quality criteria, combining sensitivity towards the desired mode-of-action with a low-noise signal and high reproducibility. “HTS-grade” assays perform robustly most importantly within the fully-automated setup. At Axxam, we use internal controls and consequent tracking of assay signal statistics to ensure and document test performance from early assay development throughout the entire HTS and follow-up process.
Compound management is crucial to supply test compounds in microplate format to be processed in automated HTS or subsequent follow up experiments. Our compound management unit consists of dedicated specialists responsible for secure long-term compound storage, and suitable logistics for picking, plating and processing (replication, dilutions, etc.). Our systems operate using either microliter tip-based or nanoliter acoustic dispensing (ECHO) technology. Consequent barcode and process tracking finally generates a seamless record of each plate and corresponding compounds in our screening database.
Microplate-based data are generally processed and analyzed using GeneData Screener software. Assay performance related to signal-to-noise and integrated experimental controls is rigorously assessed and documented in our central database. All experiments need to comply with predefined quality criteria. Data analysis is handled by a specialized team of data scientists tailoring analysis and reporting to the individual project needs and providing an instance of peer review in our workflow. The group also integrates chemoinformatic expertise applied at multiple steps in our hit identification process to minimize the risk of ‘false negatives’, to capture features of emerging structure-activity relationships, and/or to extend and enrich screening results also into the space of commercially available analogues.
Following the elimination of false positives, i.e. statistical events originating from random biological noise and/or technical errors, through simple re-testing, screening hit lists still contain large numbers of compounds acting through off-target or otherwise undesired mechanisms. To discriminate desired from unwanted hit compounds, we typically tested them in a set of secondary assays to probe for target specificity, selectivity and mode-of-action (MoA). The design of these secondary assays (or screening cascade) is dictated by the target, the assay technology used for primary screening and the desired MoA.
At Axxam, the structural integrity of hit compounds is generally tested by LC/MS. Upon request, some basic physico-chemical properties, like lipophilicity or solubility, and selected baseline ADME characteristics, e.g. plasma and hepatocyte stability or membrane permeability, can be measured to facilitate hit prioritization in the downstream process.
The selection of optimal hits holds immense importance in drug discovery, exerting a profound influence on the downstream program success. Our HTSPLUS package includes a thorough hit qualification from both the biological and chemistry perspectives, aiming to equip our clients with comprehensive insights into their hits supporting their further decision-making process.
By increasing the likelihood of identifying the best-suited hit compound, minimizing time and cost, mitigating the future risk of failure and enhancing the prospects of developing a successful drug candidate, this critical process shapes the trajectory of drug development.
The key to hit qualification within the HTSPLUS is the quick expansion of the knowledge around the most promising hit compounds delivered by HTS. Activities to further qualify hits will include the resynthesis of hit compounds, analoging via catalogue and/or synthesis of ‘strategic analogues’, together with the quantitive assessment of basic compound properties related to their physicochemical and most basic ADME properties. It also includes the rigorous testing of specificity, selectivity (potentially including orthologues) and mode-of-action (MoA) of all newly generated compounds. Results will confirm the structural identity of the hit compounds, further consolidate the target specificity and desired MoA, and provide initial insights into emerging features of the underlying structure-activity relationship and compound property profiles. An initial check of the small molecule intellectual property landscape around hit compounds completes the package. All data together will allow a well-informed hit selection process to ensure placing downstream investments on the right candidates emerging from the qualification process.
At Axxam, we utilize CDD Vault, a powerful cloud-based informatics platform by Collaborative Drug Discovery, to streamline the management and analysis of data. This tool allows us to securely store and manage research data with seamless efficiency and flexibility as well as sharing them with our clients.
Key features and benefits:
- Secure data management: secure and centralized data storage with an intuitive web interface.
- Flexible architecture: highly customizable to the unique needs of each research project. Whether it's chemical data management or bioassay analysis, CDD Vault offers the flexibility to cater to diverse research demands.
- Integrated data analysis: supports the management and the analysis of bioassay data integrated with chemical information, empowering our scientists to perform Structure-Activity Relationship (SAR) studies and cross-disciplinary analysis.
- Enhanced collaboration: By providing a centralized platform, it enhances collaboration within all players of a research project. with seamless data integration and sharing.
By utilizing CDD Vault, Axxam is able to offer clients with not only advanced scientific expertise but also a cutting-edge platform that simplifies complex data management and enhances collaboration, precision and security.
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From gene to validated and qualified hits high-throughput screening