Drug Discovery


References 1 Kinch, MS et al. DDT, 2014 Aug;19(8):1033-9. 2 Fleming, A. Br Med Bulletin, 1944 Jan; 2(1): 4-5. 3 Brimblecombe, RW et al. Br J Pharmacol., 1975 Mar; 53(3): 435-436. 4 Harrisson, R . Nature Reviews, 2016 Dec; 15: 817-818. 5 Schuhmacher, et al. J Trans Med. 2016 Apr 14:105. 6 Lipinski, C. DDT, 2004 Dec; 4:337-341. 7 Bohacek, RS et al. Med. Res. Rev., 1996; 16:3-50. 8 Singh, et al. J Biomol Screen. 2014 Jun;19(5):640-50. 9 Kümmel, A et al. J Biomol Screen. 2012 Jul;17(6):843-9. 10 Smith, K and Horvath, P. J Biomol Screen. 2014 Jun;19(5):685-95. 11 Blom, H and Brismar, H. J Intern Med. 2014 Dec;276(6):560-78. 12 Chéreau, R et al. Methods. 2015 Oct 15;88:57-66. 13 Kazi et al. The SAGE Encyclopedia of Stem Cell Research, 2nd Edition, 2015 Jul; SAGE Publications, Inc, Eric E. Bouhassira Editor. 14 Jones et al. Methods Mol Biol. 2012; 814:341-52. 15 Ravi et al. J Cell Physiol. 2015 Jan;230(1):16-26. 16 Miranda et al. Bioengineering 2018 Jun; 5, 49. 17Yuan et al. Bioengineering 2018 Jul; 5(3), 57. 18 Grundmann, M. Curr Protoc Pharmacol. 2017 Jun; 77:9(24)1-9. 19 Schulz et al.Curr Opin Biotechnol. 2018 Aug; 25(55):51-59. 20Winter et al. SLAS Discov. 2018 Jul; 23(6):561-573. 21 Hart et al. Cell. 2015 Dec 3;163(6):1515-2. 22 Karlgren et al. Drug Metab Dispos. 2018 Aug 20. 23 Legut et al. Blood, 2018 Jan; 131(3): 311-322.


technologies are well-suited to measure holistic cell responses in an unbiased and pathway-specific manner. DMR biosensors are composed of a resonant


waveguide grating surface capable of reflecting an incoming white light source at different wave- lengths. Magnitude of the reflected light wave- length recorded in DMR is proportional to the amount of matter (eg cytoskeleton elements, pro- teins) brought into proximity of the biosensor. When cells spread or grow on the biosensor after drug treatment, there is a positive shift of the reflected wavelength since additional cytoskeleton elements are brought to proximity to the sensor. The opposite phenomenon is observed when cells contract or die. Further to measuring cellular mor- phological changes through the modulation of cell surface receptors (eg GPCR and RTKs) or intracel- lular enzyme (eg kinase, phosphatase, etc), DMR can also measure several types of interactions involving purified molecules such as small ligand binding to proteins and protein-protein interac- tions. It is worth mentioning that, contrasting with CDS, DMR can measure phenotypic changes occur- ring with cells used at various confluency states. CDS biosensors consist of electrode arrays


where confluent cells form an ‘isolating interface’ generating impedance. When voltage is applied on biosensors, electrodes produce electrical currents flowing around and between cells (eg extracellular current) and through cells (eg transcellular cur- rent). When cells contract or die after drug treat- ment, gaps between cells appear attenuating the isolating interface and a decrease in impedance is recorded. Conversely, an increase in impedance is recorded when cells spread or grow. Contrasting with DMR, CDS requires cell confluency and can- not be applied to measure molecular binding events involving purified components. On a different note, mass spectrometry is now


growing in popularity as a label-free biomarker detection method in bioscience research. Matrix- assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI TOF MS) was shown to have great potential for imaging on tissue sec- tions19. When coupled to liquid handling to man- age compounds and liquid chromatography to desalt samples prior to injection, MALDI TOF MS can perform HTS with speed, sensitivity and accu- racy comparable to label-based technologies20.


The rise of gene-editing technologies Gene-editing technologies are undoubtedly among the most impactful scientific breakthroughs of the last century. These technologies allow scientists to


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add, delete or modify genetic material at specific loci in the genome. The CRISPR-Cas9 method has a lot of popularity in the scientific community since it was shown to be more accurate and efficient than other gene editing systems, while being fast and cheap to execute. Gene editing technologies are used all along the drug discovery workflow from target identification to the generation of new mod- els and therapies. High resolution CRISPR screens of gRNA libraries allow identification and valida- tion of new disease targets, namely in oncology21. CRISPR was further applied in studies of drug absorption, distribution, metabolism and excretion (ADME) and for ADME model generation22. One of the most spectacular use of CRISPR-Cas9 is in immuno-oncology where researchers engineer T- cells to treat either hematological or solid tumours23. The engineered T-cells can be thus (re)injected to cancer patients during autologous or allogenic grafting. Under co-ordinated translational oncology efforts, an increasing number of clinical investigations involving CRISPR-Cas9 engineered T-cells are under way while specialised organisa- tions started offering T-cell engineering and grafting services to cancer patients.


Summary Today’s drug discovery scientists are increasingly facing challenges inherent to the complexity of dis- eases and the need to bring safer drugs to patients faster and at a lower cost. The drug discovery workflow, developed a few decades ago for HTS, is evolving under the guidance of multidisciplinary teams, including clinicians. Researchers benefit from new powerful technologies allowing for a better identification and validation of new disease targets. Technological advances also allow scien- tists to set more biologically-relevant disease mod- els and develop unbiased assays to find more effi- cient and safer therapies based on either small or large molecules.


DDW


Dr Roger Bossé is a Global Product Line Leader, Life Sciences & Technologies, at PerkinElmer, Inc. Dr Bossé holds a PhD in Pharmacology from the University of Sherbrooke (Quebec, Canada). He completed his Post-Doctoral


training in


Neuroendocrinology in Marc Caron’s lab (Cell Biology, Duke University, NC).


Drug Discovery World Fall 2018


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