This article is based on a poster originally authored by Benjamin Bader, Volker Badock, Katrin Nowak-Reppel, Roman C. Hillig, Martin Lange, Jörg Weiske, and Holger Steuber, which was presented at ELRIG Drug Discovery 2024 in affiliation with NUVISAN ICB GmbH.
This poster is being hosted on this website in its raw form, without modifications. It has not undergone peer review but has been reviewed to meet AZoNetwork's editorial quality standards. The information contained is for informational purposes only and should not be considered validated by independent peer assessment.
Successful drug discovery relies on advanced technology platforms and comprehensive expertise across all disciplines in the value chain. As indicated by increasing attrition rates in drug discovery over the recent decades, various risks contribute to the success or failure of a drug discovery campaign.
Potential liabilities could be linked to the validation of the target and disease hypothesis, low druggability, unsuitable assay systems, false hit selection, missing target engagement, toxicology and safety issues, or lacking efficacy. This study examines the essentials based on experience from a biochemical and a cell-based HTS project.
Target significance
RAS-SOS1
Figure 1. Target introduction. Image Credit: Benjamin Bader et al., in partnership with ELRIG (UK) Ltd.
- 3 RAS isoforms (H-, N-, K-RAS) act as molecular switches, oscillating between GDP- and GTP-state
- 30 % of human cancers feature RAS mutations (mainly positions 12 and 61) → render RAS constitutively active
- GxP binds with picomolar affinities, with millimolar concentrations in the cell → “undruggable target”
Hippo pathway (YAP1/TAZ)
- Physiological functions: Regulation of organ growth and size, cell proliferation and differentiation, embryogenesis, and tissue regeneration/wound healing
- Integration of upstream signaling, e.g., Wnt, GPCR, and RHO
- YAP1/TAZ are overexpressed in human cancers, interact with TEAD transcription factors, and activate target genes:
- Increased cell proliferation
- Resistance to apoptosis
- Induction of cell migration
- Therapeutic strategies that target dysregulated Hippo components could be promising approaches for the treatment of a wide spectrum of diseases
Image Credit: Adapted from Piccolo S et al., Clin Cancer Res, 2013
Induction of liver cancer by Yap1 overexpression in mouse. Image Credit: Liu-Chittenden Y et al., Genes Dev, 2012
Hit identification
Parallel hit finding: HTS and fragment screening
Image Credit: Benjamin Bader et al., in partnership with ELRIG (UK) Ltd.
Pathway screen with reporter cell line
Image Credit: Benjamin Bader et al., in partnership with ELRIG (UK) Ltd.
Hit characterization & derisking
Target engagement & mode-of-action
Surface-Plasmon-Resonance (SPR): Compound 1 is disrupting, but fragment 1 is stabilizing the KRAS-SOS1 interaction. Image Credit: Benjamin Bader et al., in partnership with ELRIG (UK) Ltd.
Thermal Shift Assay, Isothermal Titration calorimetry and native MS: Compound 1 identified as a SOS1 binder. Image Credit: Benjamin Bader et al., in partnership with ELRIG (UK) Ltd.
X-Ray: Fragment 1 and Compound 1 bind into same surface pocket of SOS1. Image Credit: Benjamin Bader et al., in partnership with ELRIG (UK) Ltd.
Target deconvolution: What is the direct target of BAY-856?
Image Credit: Benjamin Bader et al., in partnership with ELRIG (UK) Ltd.
Lessons
Success factors for biochemical screens:
- Employ multiple hit-finding approaches for targets with low druggability.
- Establish robust secondary and orthogonal assays for reliable hit validation.
- Confirm target engagement through biophysical methods.
- Integrate X-ray structural support early in the project.
Success factors for cell-based phenotypic/pathway screens:
- Include toxicity controls during primary and secondary HTS stages.
- Use well-established secondary and orthogonal assays for effective hit validation.
- Implement target deconvolution methods, such as CRISPR-KO, in silico models, and CETSA.
- Confirm target interaction with biochemical, biophysical, and X-ray techniques.
References
- Hillig, R.C., et al. (2019). Discovery of potent SOS1 inhibitors that block RAS activation via disruption of the RAS–SOS1 interaction. Proceedings of the National Academy of Sciences, 116(7), pp.2551–2560. https://doi.org/10.1073/pnas.1812963116.
- Graham, Keith, et al. (2024). Discovery of YAP1/TAZ Pathway Inhibitors through Phenotypic Screening with Potent Anti-Tumor Activity via Blockade of Rho-GTPase Signaling. Cell Chemical Biology, March. https://doi.org/10.1016/j.chembiol.2024.02.013.
About NUVISAN GmbH
Founded in Europe, NUVISAN is a fully integrated contract research and development and manufacturing organization (CRO/CDMO) that offers unique, high-quality, and tailored integrated solutions along the drug discovery and development value chain. With four sites in Germany (Berlin, Grafing, Neu-Ulm, and Waltrop) and one in France (Sophia Antipolis), NUVISAN has a 40-year track record of partnering with our biotech startup, pharma, nonprofit, and venture capitalist clients to find solutions to their needs—from target identification to the patient.
Operating under the name NUVISAN since 2010, ALS Limited, the global leader in testing, acquired NUVISAN on April 1, 2024, forming the most advanced drug discovery and development organization providing solutions across continents. ALS has operations in more than 350 locations, across 55 countries, and on six continents.
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