3D micro-cancers reduce animal use in drug development

Dr Louis Chesler from The Insitutue of Cancer Research was awarded an NC3Rs project grant in 2010. He has used the funding to develop a 3D in vitro assay for early preclinical cancer studies along with co-investigator Professor Sue Eccles.

Research details

Principal Investigator: Dr Louis Chesler
Co-Investigator: Sue Eccles, Professor of Experimental Cancer Therapeutics
Organisation: The Institute of Cancer Research
Award: £291,388, in 2010, over 24 months
Title: Replacement of animals in cancer drug developement by using 3D in vitro functional assays for increased predictive power.

Read more about Dr Chesler's research 

Case study

There is a need to improve the cancer drug development pathway

Paediatric solid tumours (such as glioblastoma and neuroblastoma) remain among the most deadly and difficult to treat of all childhood cancers. Disease relapse is frequently characterised by metastasis and resistance to conventional treatments. There is a major clinical need to develop new drugs for these and other types of cancers, including those found in adults. Drug attrition rates for cancer are higher than for many other therapeutic areas and a number of factors contribute to this.

One key reason is the failure of preclinical strategies to accurately select appropriate targets and evaluate novel therapeutics. Another problem in paediatric cancer, and especially in solid tumours, is the difficulty in obtaining tumour tissue to study in order to increase understanding about drug responses.

Preclinical testing typically involves applying compounds to simple 2D tumour cell culture systems to assess for inhibition of proliferation before selecting the best candidates for evaluation in animal tumour models. The 2D assays fail to reflect the complexity of tumours within the body and particularly the limited drug access to solid tumours that is observed in patients.

Attention has therefore focused on developing 3D cultures which more closely mimic the in vitro tumour microenvironment, including hypoxic regions and necrotic cores. The true value of such models is dependent on the ability to generate reproducible tumour spheroids (micro-cancers), combined with tools that allow automated analysis. In 2010, Dr Louis Chesler and Professor Suzanne Eccles at The Institute of Cancer Research (ICR) were awarded NC3Rs funding to develop such a system.

Micro-cancers to study tumour growth, invasion and angiogenesis

Initial experiments using 40 different cancer cell lines demonstrated the ability of the cells to form spheroids or micro-cancers spontaneously in culture. Micro-cancers from cell lines representing hard to treat diseases (glioblastoma, oral squamous cell carcinoma and triple negative breast carcinoma) were subsequently selected for development of functional assays for target validation and drug evaluation.

The micro-cancers show the key cancer hallmarks of cell migration, invasion and angiogenesis. By growing them singly in 96-well, round-bottomed microplates and utilising advanced high content imaging, the system provides for the first time a high throughput and quantitative screening tool for the development of novel cancer drugs.

Clinically important discoveries using the micro-cancers

The micro-cancers have been used to test a range of compounds, identifying those with enhanced potency against cell migration and invasion compared with proliferation, suggesting a particular use for invasive and/or metastatic cancers. In addition, using genetic knockdown, it has been possible to identify key roles of signalling molecules (such as the protein kinase, MAP4K4) in tumour cell motility and invasion, not detectable in standard 2D assays.

Micro-cancers have also been generated for prostate, colon and lung cancer and particularly those in which local invasion is a major clinical problem, such as glioblastoma and head and neck squamous cell carcinoma (HNSCC). The 3D assays revealed in vitro phenotypes in HNSCC not evident in standard 2D assays (such as enhanced growth and invasion, mimicking their behaviour in vitro) and these are being exploited to streamline the discovery of novel biomarkers and therapies to overcome drug resistance.

Reducing animal use by more effective selection of compounds

Use of the micro-cancers in drug discovery projects has enabled researchers at the ICR to select only those compounds which are predicted to have optimal efficacy in vitro. As a result, in one project in particular, approximately 30% of compounds that previously would have progressed to in vitro tumour testing have not advanced into animal studies.

Promoting the uptake of micro-cancers

A methodology article published in BMC Biology achieved status of ‘highly accessed’ - in the top ten in just its first year with over 16,000 readers to date.

Ten collaborations have been formed with ICR colleagues, national and international institutions and a pharmaceutical company to exploit the new assays. Dr Chesler and Professor Eccles are also collaborating with companies to further miniaturise the assay and to refine and extend the software. This will enable the assays to be used to quantify additional features of malignancy and to increase throughput such that screening for inhibitors of tumour cell proliferation, invasion and also angiogenic potential in 3D is a practical reality.

This case study was published in a review of our research portfolio in November 2013.