Interview, Opinion

INTERVIEW: Kenneth Ewan – My Experience with Translational Science and Drug Discovery

Dr Kenneth Ewan

Contributed by Kenneth Ewan

“My Experience with Translational Science and Drug Discovery”

Ken’s background

My PhD and early postdoc work focussed on developmental biology ending with a productive project at the Lawrence Berkeley National Laboratory in California investigating TGF-b1’s role in mammary gland development, homeostasis and its response to ionising radiation. My experience up to this point was basic research at universities and institutes that was funded by research grants. Because the mammary gland biology/breast cancer research field had by then become quite competitive, I decided to switch to a research area that was more translational in nature.

My opportunity came with a project in Trevor Dale’s lab to screen for Wnt pathway inhibitors. Oncogenic Wnt signalling occurs in almost all colorectal carcinogenesis and is seen in many other cancer types. However, none of the core proteins are obvious molecular targets for small molecule inhibitors. Thus, the approach was to use a Wnt reporter cell line to screen for potent inhibitors first and identify the molecular targets later. The funding came from Cancer Research Technologies (CRT), the commercial arm of Cancer Research UK, which also provided the chemical library to screen. We collaborated on this project with the Institute of Cancer Research (ICR) which has very talented chemists and experts on ADME (administration, degradation, metabolism, excretion) that can drive the development of a drug from the original hit compound to one that is suitable to be used in a clinical trial. At the time I joined the project, a Wnt reporter line had already been made. The ICR also had a high-throughput screening unit to carry out the initial screen of a library of 80,000 compounds. Thus, my role was to investigate the mechanism of action of the hit compounds, which were carried out using a series of reporter and biochemical assays. The funding structure from CRT is sequential 1-2 year grants that that can allow proof-of-concept for a drug discovery programme but which can quickly terminate it as well (the “Go or No-Go” decision points). CRT only funds the initial stages of the pre-clinical stages of a drug discovery project; commercial funding is required for further progression. Nonetheless, CRT’s support allowed the collaborative team to develop an assay cascade, which allowed us to identify four chemical series that showed potential for further development. Description and analysis of three of these chemical series was published in Cancer Research in 2010.

One day at a poster

A breakthrough in prolonging the Wnt pathway drug discovery project came with the involvement of Merck Serono, a German pharmaceutical firm. By chance, a Merck Serono drug discovery scientist that previously knew Trevor Dale from his time at the ICR viewed my poster at an NCRI conference in 2006. At the time, Merck Serono was very interested in collaborating with academic research team partners. They were interested in the approach of our drug discovery project, the pathway it was targeting and one of the chemical series. This series had been shown to not have any chemical groups that would chemically interact with DNA etc and was predicted to be ‘clean’ with respect to toxicity and stability. After prolonged negotiation, Merck Serono signed a collaboration agreement with Cardiff University, the ICR and CRT to start in early 2009 (just in the nick of time for me and a colleague who was also funded from the original CRT grants). As a result, Merck Serono acquired the rights to our Wnt reporter line and the chemical series they were interested in. In return, they funded a large team for four years (renewed yearly) and screened their library of 600,000 compounds.

poster sessionMy role was initially to help with identification of the molecular target of the Wnt pathway inhibitor series that Merck Serono had just acquired rights to, using an approach involving the labelling of cells with amino acids incorporating different stable isotopes and mass-spectrometry (known as SILAC). My experiments didn’t identify the target protein but did inform further progress. The key to eventual success in this endeavour was the synthesis of highly potent, immobilizable molecular probes based on the Wnt inhibitor chemical structure and also outsourcing the work to a contract research company that specialised in the SILAC approach. This cost a lot of money but did identify the target kinases CDK8 and CDK19, which function in a large transcriptional complex of proteins called “Mediator”. These two proteins were also identified in kinase profiling screens. By this time, I was rather more successfully testing the effectiveness (efficacy) of members of the chemical series in Wnt-driven intestinal hyperplasia and mammary tumour animal models. Additionally, I also used 3D tissue culture versions of the hyperplasia and tumour animal models to test efficacy. The body of work encompassing the screening, target identification, cell line and animal model work was published at the end of last year in Nature Chemical Biology.

The project has wound down but work is still continuing to determine if the series (and the molecular target) is suitable to initiate clinical studies. The major benefit for me to be on a drug discovery project from early on to the end of the preclinical phase is to understand the process itself and carry out some of the assays needed to progress it. Another benefit is meeting more people in the field that could be useful later. The 3D tissue culture aspect of the project led to some of my present activities.

The current picture

Three dimensional cultured tissue fragments termed “organoids” are a new and evolving technique relevant to drug discovery and tissue regeneration. The success rate of cancer drug discovery programs has been hampered by the use of tumour-derived cell lines that do not closely resemble tumours in patients due to the selective pressures of adapting the cells to grow two-dimensionally on plastic. In contrast, organoids are self-renewing and contain the full range of cell types present in a tissue or tumour. Andrew Hollins and Luned Badder in the lab pioneered the culture of individual patient-derived colorectal tumour organoids to determine if drug response correlates to oncogenic genotypic changes. My contribution has been to firstly use organoids in xenograft mouse models and secondly to trial a label-free imaging technique known as CARS on organoids exposed to drug. The CARS work led to a recent multidisciplinary award from Cancer Research UK. I have been peripherally involved on a lab project in collaboration with a Bath University spin-out company called Cellesce whose aim is to bulk up organoids that can then be sold to end-users for assays. Some funding for this came from Innovate UK. This company is planning to set up in its own space soon in Cardiff. In addition, the lab still carries out organoid and mouse model assays for Merck-Serono. Unfortunately, the present work with Merck-Serono is not continuous and can only be used to ‘top up’ time on a contract. This is the downside of acting as a ‘contract research organisation’ for Big Pharma. There is much more benefit for the lab as a whole in terms of paying for expensive assays and occasional pieces of equipment.

The takeaway message

In summary, working with private companies such as start-ups and Big Pharma has the advantages of providing different opportunities for funding and looking at projects from a different angle compared to purely academic research. It also provides an avenue to transition into working for such companies (although I haven’t done this so far).

About the contributor:

Dr Kenneth Ewan

Dr Kenneth Ewan is a long-standing Research Associate based within the Molecular Biosciences division in the lab of Prof. Trevor Dale.

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