Replacing Mouse Immunotherapy Models with Human Colorectal Cancer Organoid - T Cell Cultures

Why did we fund this project?

This award aims to replace the use of mice in some T cell immunotherapy studies by developing an organoid system for testing genetically-engineered T cells.

Patient T cells can be genetically engineered to better recognise specific proteins on cancer cell surfaces and used in immunotherapy to treat cancer. T cells can also be engineered to improve survival and migration towards cancerous cells. Modifications to T cells need to be tested for efficacy, which is typically done by genetically editing mouse-derived T cells and using these to treat a tumour in another mouse. To replace these animals, the student, with Professor Awen Gallimore, will develop an organoid system using colon tissue from patients with colorectal cancer. They will optimise this system to assess the anti-tumour effects of genetically-modified human T cells and in collaboration with Psioxus Ltd., a cancer therapeutics company, explore further applications of the organoid system for viral cancer treatments.

Cancer immunotherapy is viewed as one of the most significant scientific breakthroughs in medicine of recent years, due in part to the success of adoptive T cell therapy. Despite many notable successes, several bottlenecks exist, which prevent this type of therapy from being successful in most cancer patients. There is ample evidence that engineering T cells to modify their functions may overcome several of these bottlenecks and this is the subject of intense research in the immunooncology field.

There is a reliance on the use of mouse models to test the efficacy of modified T cells. In our own lab, we use mouse models to test methods of improving the efficacy of genetically engineered cancer specific T cells. Mice are also required to generate tumour cell lines and T cells for immunotherapy therefore the numbers of mice used for such studies is far larger than the number of mice, which act as direct testbeds for anti tumour T cell responses.

In this project, our overall aim is to develop a system, which replaces use of mice for T cell immunotherapy studies using human organoids and genetically engineered human T cells. Organoids offer the potential to replace animal use at multiple points in the T cell immuno-oncology research pathway. They can be used in experiments ranging from the testing of new ideas through to safety testing of novel therapies. Organoids can be derived from genetically diverse, patient specific tumours and can be readily  subjected to genetic modification. We estimate that, in our own studies alone, 2000 mice will be used over a 5-year period for adoptive transfer studies, which could be replaced with an optimised human organoid-T cell co-culture system. In addition, following a PubMed search for the following terms: Cancer, T cell, Mouse, Adoptive Immunotherapy we estimated the number of animals used in research published over 3 months. From October to December 2021, we found that around 2,000 animals were used for adoptive cell therapy experiments. This exercise was repeated with similar findings from April to June 2022. Whilst this approach has limitations, it is reasonable to assume that the number is an under-estimate of the total number of animals used as many animals would have been used for preliminary work or repeat experiments, not represented in the final publications.

We have already grown a bank of human organoids derived from malignant and non-malignant colon tissue from patients with colorectal cancer. We have performed characterisation of the organoids and developed computational methods for their quantification. Moreover, we have conducted preliminary live cell microscopy experiments to enable rapid and accurate measurements of T cell mediated organoid death. In this study, we will optimise the methodologies and develop a robust and reproducible assay for assessing the anti-tumour effects of modified T cells. In collaboration with an industrial partner (Psioxus Ltd), we will also use the organoids to test the cancer selectivity of novel oncolytic viruses.

These viruses have been engineered to deliver immune modulating proteins to the tumour microenvironment where they may alter the behaviour of co-cultured T cells. A human organoid, T cell co-culture system will replace the need to use immunocompromised mice for testing such viruses. For both purposes, we have access to patient matched peripheral blood mononuclear cells and have an established bank of antigen specific T cell lines and clones. Using these human materials, we aim to optimise techniques which will allow us to measure the ability of genetically modified human T cells to kill cancer cells. As well as replacing use of mice in our own lab, the legacy of this project is the implementation of our methods by labs within academia, biotech and Pharma across the globe.