3D bioprinted microtissues to develop patient-specific non-animal technologies (NAT) in cancer drug development

Why did we fund this project?

This award aims to replace mice in preclinical testing of leukaemia therapeutics using bone marrow stem cells in a 3D bioprinted organoid platform.

Improving preclinical models to increase translatability and reduce drug attrition in clinical trials is a priority in cancer research. Cell lines used in in vitro studies do not possess all the biological characteristics of cancer cells in patients. Patient samples are often available but commonly fail to grow in ex vivo culture. This creates a reliance on patient-derived xenograft (PDX) models, where tissue taken from patients is transplanted directly into immunocompromised mice and maintained by passaging from mouse to mouse. These experiments are classified as moderate severity under the UK’s Animals (Scientific Procedures) Act 1986 due to the level of suffering caused by the growth of the tumour. In her NC3Rs-funded Training Fellowship, Dr Deepali Pal optimised an in vitro culture method for supporting patient-derived leukaemia samples using bone marrow stem cells produced through induced pluripotent stem cell technology. Using this approach, she replaced mice in the use of 67 drug tests in a year at Newcastle University, replacing 73% of 3600 (2680) mice locally.

The student will use bioprinting in combination with Deepali’s in vitro method to enable patient-derived leukaemia samples to be cultured in 3D to better represent the in vivo environment. As part of their training, the student will collaborate with Alcyomics Ltd, who specialise in developing in vitro assays for drug safety and efficacy testing. They will work to ensure all protocols developed are scaleable and compliant with good laboratory practice safety study requirements, enabling easier uptake of the model in the drug discovery pipeline. The student will develop skills in tissue engineering, 3D cell culture and differentiation protocols.

Impacts

• Further funding: Assessment of an in vitro acute lymphoblastic leukaemia model for high-throughput arrayed CRISPR screening, Technologies to Tools grant, £42,268.
• Patient and public involvement opportunity: Finding safer and kinder ways to treat to treat children's leukaemia (Cancer Research UK).

The 3Rs aim of this project is to replace animals in preclinical testing of anti-cancer medicines. Our scientific aim is to develop a scalable patient-specific organoid/microtissue (organoids are spheroid structures that act as miniature tissues) platform and to apply this model following validation to identify new treatments for blood cancers. We will work with our commercial partner Alcyomics Ltd and academic collaborators, throughout the project lifespan to ensure we meet  requirements for optimal uptake of our platform by industry and academia. Improved strategies to reduce side effects and avoid treatment failure are urgently needed in leukaemia treatment. Cancer drug development has the highest “drug attrition” rates, meaning that very few newly developed medicines are successful in clinical trials despite being deemed suitable in preceding preclinical studies. Hence we need preclinical models with improved clinical translatability. Cell line models do not retain cancer cell biological properties characteristic of the patient. Patient derived leukaemia cells from clinical samples are ideal; however, these cells fail to grow outside the patient’s body possibly due to lack of surrounding BM (bone marrow) cells. Hence the mouse BM is commonly used as an external “home” for culturing patient derived leukaemia cells. Leukaemia research by our group at Newcastle requires 3600 animal procedures every year. These animal experiments are classified as “moderate severity”; meaning they cause significant pain, suffering and distress and clearly detectable disruptions to the animal’s normal state.

We developed synthetic BM cells from human stem cells which supported the growth of patient-leukaemia cells whilst retaining chief cancer cell properties so they behaved similarly to how they would have behaved in the patient’s body. Local metrics confirmed that using this pilot approach we replaced mice in 67 drug tests last year. Given minimum of 40 animals are needed per drug test we replaced 2680 animals (out of 3600) which constituted a minimum 73% local animal replacement. Besides requiring detailed validation to ensure these proof-of-concept metrics are reproducible key limitations of our existing preliminary approach are that our model applies to only a select range of leukaemia samples and furthermore incorporates labour-intensive techniques lacking scalability which hinders its uptake by the wider scientific community. To overcome these obstacles in this project we propose to use our synthetic human BM cells to develop an automated 3D BM-organoid approach to culture and study patient derived leukaemia cells. Through pilot experiments we have shown that preliminary 3D BM microtissues provide superior support to leukaemia cell proliferation than preceding 2D approaches and hence we anticipate that the proposed new 3D approach will allow us to grow additional leukaemia samples consequently replacing even larger number of animals. Furthermore, following validation steps proposed in this project we will generate standardised protocols to facilitate wider endorsement of our synthetic BM-organoids through existing and new collaborations. Developing an automation-based approach will allow us to test new medicines at a larger scale and generation of standardised protocols will ensure that we overcome current barriers to the uptake of our platform.

Home Office returns and annual expenditure reports from major UK cancer research funders indicate that 9,000 animal procedures are used in leukaemia research annually. Following wider endorsement during this project lifespan, our local 73% reduction in animal numbers replicated nationally would mean a minimum target reduction of 6500 animal experiments per year in leukaemia research. Furthermore, our platform will provide proof-of-concept preclinical models for application to other solid tumours to replace even larger number of animals in cancer research.