Research by Structural Genomics Consortium and DiscoveRx Points to New Multi-Targeting Approaches to Cancer Therapy

OXFORD, United Kingdom and FREMONT, Calif., March 5, 2014 /PRNewswire/ -- The Structural Genomics Consortium (SGC) and DiscoveRx Corporation today announced the publication of findings that suggest compelling new multi-targeting approaches for cancer therapy. In a study entitled "Dual kinase-bromodomain inhibitors for rationally designed polypharmacology," which appeared on-line in Nature Chemical Biology (http://www.nature.com/nchembio/index.html), the researchers demonstrate that several clinical kinase inhibitors also potently inhibit diverse bromodomain epigenetic reader proteins.

Kinase inhibitor-based targeted therapies have had clinical successes. However, a substantial proportion of patients fail to respond initially, and acquired resistance to these drugs remains problematic. Inhibition of multiple oncogenic proteins in the same tumor is an established strategy to address these challenges, but the discovery of inhibitors targeting multiple rationally chosen kinases is difficult, and combination therapy approaches require complex clinical investigations.

The finding that several oncology-focused clinical kinase inhibitors also potently inhibit bromodomains, including the established cancer target BRD4, demonstrates the feasibility of a "single agent, inter-family" multi-targeting approach. The structural biology data presented indeed suggest actionable dual inhibitor design strategies. Co-senior author Stefan Knapp, Principal Investigator at the SGC (based at the University of Oxford) commented, "The diversity of the kinase catalytic site and the acetyllysine binding pockets in bromodomains will allow optimization of inhibitor potency for both target classes, which will facilitate the development of therapeutic dual inhibitors."

Among the kinase inhibitors shown to have potent BRD4 activity are the JAK2-FLT3 inhibitor TG-101348 and the PLK1 inhibitors BI-2536 and volasertib. "Since FLT3 and BRD4 can be independent drivers in acute myelogenous leukemia, the TG-101348 data raise hope for the development of an optimized dual FLT3-BRD4 inhibitor, which would be anticipated to improve patient outcomes," said co-senior author Daniel Treiber, Sr. Director of Research at DiscoveRx.

Co-author Neil Shah, Leader of the Hematopoietic Malignancies Program at the UCSF Helen Diller Family Comprehensive Cancer Center, agrees that multi-targeting single agent therapies could offer significant advantages. "Attempts to clinically test therapeutic combination strategies that exploit synergistic interactions are often hampered by significant obstacles such as the potentially unacceptable cost and toxicity of combining two drugs, as well as practical difficulties inherent in working simultaneously with two pharmaceutical companies," he said. "This work excitingly demonstrates that in some cases, rational medicinal chemistry efforts can circumvent many of these issues and potentially rapidly advance medical science."

Importantly, the dual BRD4-kinase inhibitors were also shown to exhibit complex, unique polypharmacologies across a panel of human primary cell disease models (BioMAP® systems). "Our strategy of using both target-based and phenotypic screening approaches represents a paradigm shift in developing single agents that can act as ready-made combination therapies that may be more efficacious and overcome clinical obstacles," said co-first author Alison O'Mahony, Sr., Director of Research at BioSeek, a division of DiscoveRx.

About the Structural Genomics Consortium
The Structural Genomics Consortium (SGC) (http://www.thesgc.org/) is a not-for-profit, public-private partnership that conducts pre-competitive research to facilitate the discovery of new medicines.  Based at the University of Oxford and University of Toronto the SGC's work contributes to new hypotheses in understanding and treating human disease, and the subsequent identification of new targets for drug discovery. The SGC's primary objectives are to produce and characterize the 3-dimensional structures of soluble proteins and of integral membrane proteins, to generate selective chemical probes for epigenetic proteins and kinases, and to release these into the public domain. As part of its mission the SGC generates medically relevant reagents and knowledge related to human proteins and proteins from human parasites, which it shares through over 250 collaborations with researchers worldwide. Since 2004 the SGC has solved over 1400 protein structures and has generated 19 chemical probes for epigenetic proteins (http://www.thesgc.org/chemical-probes/epigenetics).

About DiscoveRx Corporation
Founded in 2000, DiscoveRx is a leading provider of next generation drug discovery screening and profiling platforms. Utilizing its three proprietary technology platforms beta-galactosidase-based enzyme fragment complementation (EFC), KINOMEscan^® and BioMAP^® (http://www.biomapsystems.com), DiscoveRx offers an industry leading portfolio of over 1000 target-based and human primary cell-based systems for oncology, metabolic disease, inflammation, autoimmunity, CNS and cardiovascular research at global pharmaceutical, biotechnology and academic institutes.  For more information, visit http://www.discoverx.com.

University of California Disclaimer
The information stated above was prepared by the Structural Genomics Consortium (SGC) and DiscoveRx Corp. and reflects solely that opinion. Nothing in this statement shall be construed to imply any support or endorsement of the SGC or DiscoveRx, or any of its products, by The Regents of the University of California, its officers, agents and employees.

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