Manipulating cholangiocarcinoma immune-phenotype in a patient derived precision-cut tumour model to improve immune checkpoint inhibition response

Why did we fund this project?

This award aims to replace the use of xenograft mouse models in some studies of cholangiocarcinoma using an ex vivo human tissue slice model.

Cholangiocarcinoma (CCA) is a rare but aggressive cancer of the bile ducts. Conventional chemotherapy has limited effects and patient prognosis is poor. An alternative therapeutic approach uses the immune system to promote a strong anti-tumour response. These immunotherapy treatments have had varied clinical success, likely due to individual differences in the tumour microenvironment. Research to understand the mechanisms of treatment response and resistance currently rely on a mouse xenograft model, which is expensive and time consuming as well as being associated with animal suffering. With funding from an NC3Rs Skills and Knowledge Transfer award, Dr Laura Randle has established an ex vivo human precision-cut tissue slice (hPCT) model derived from patient tumour samples providing a more relevant human tissue model of CCA. The student will build confidence in the use of hPCT model to encourage its wider uptake by demonstrating its utility in better understanding the contribution of the tumour immune environment to CCA progression. They will then test treatment regimens to increase the efficacy of immunotherapy against CCA.

Cholangiocarcinoma (CCA) is an aggressive malignancy with increasing incidence and persistently poor prognosis. Conventional-chemotherapy has limited efficacy prompting novel targeted approaches. Immunotherapeutic strategies such as immune-checkpoint blockade (ICB) aim to harness the host-immune system to unleash an effective, durable anti-tumour response. The TOPAZ-1 trial suggests benefit from PDL1-ICB (durvalumab) addition to conventional-chemotherapy. However, only a subset of patients (ORR 26%) will likely derive significant benefit, and a better understanding of the tumour-microenvironment (TME) is required to understand mechanisms of response/resistance.

Mouse-models of hepatobiliary cancer are costly, time-consuming and raise ethical concerns. Their ability to replicate human-disease, partially explains high-attrition rates seen upon translation into clinical-trials. Building upon our recent NCRS SKT award we have established a specimen collection network and precision-cut tissue slices (hPCTS) model in Liverpool. These patient-derived 3D-cellular structures can be cultured ex-vivo from normal and tumour tissue enabling us to utilise human-tissue to model human-disease. Here we propose their implementation to further our understanding of the CCA immune-TME further reducing our reliance on animal models, particularly the xenograft mouse model. ICB-mediated anti-tumour responses rely on cytotoxic T-cells infiltration to recognize and destroy tumour cells. Immune 'hot' tumours have increased CD8+T-cell infiltration and improved ICB therapy  responsiveness. Conversely, immune 'cold' tumours show reduced cytotoxic T-cell infiltration and high proportions of immunosuppressive tumour-associated macrophages and T-regulatory cells. The suboptimal response suggests many CCA tumours have a 'cold' phenotype, comparable to other solid tumours. Combination strategies that modulate tumour immune-phenotype from 'cold' to 'hot' could significantly increase ICB clinical-effectiveness and remains underexplored in CCA.

Our scientific goal is to augment the CCA hPCTS immune-TME and assess responses/resistance to various immunotherapeutic/chemotherapeutic regimes, which have potential to improve CCA ICB clinical-response and simultaneously further the exploration of immunotherapy response/resistance mechanisms and identification of corresponding biomarkers. This technique will replace the need to conduct animal experiments to investigate the contribution of tumour immune environment to CCA disease progression and strengthen this approach as a translational model, highlighted in the 2020 CCA consensus statement as an urgent requirement. Around 8000 mice are used each year across all areas to explore CCA. We anticipate that validation of the CCA hPCTS immune model will lead to a replacement of 816 animals per year in global labs which study immunological aspects of CCA, a reduction of 10% mice. Within our lab hPCTS has currently replaced 38 mice, with local exploration outside our immediate research group now visible. We will further promote this immune model through training workshops and symposium promoted to immunology and oncology audiences, publications and presentation to our research networks / consortia, continued engagement with patient groups and the CCA community.