Developing patient derived tumour organoids to replace mouse models in understanding and improving anti-tumour T cell responses.

CD8+ ‘killer’ T-cells (T-cells) are fundamental in immune surveillance for recognition and destruction of tumour cells, by detecting tumour-specific proteins (antigens) displayed at the cell surface on Major Histocompatibility Complex class I (MHC-I). Effective T-cell targeting of tumours relies on a tightly regulated and effective antigen processing and presentation (APP) pathway, a system present in all mammals however is highly complex in humans due to the variation in MHC-I expressed in individuals. Therefore, mouse models are unlikely to fully recapitulate human APP and may not be effective in understanding the mechanism and effect of this complex system. During tumour evolution, several mechanisms are adopted to escape detection by T-cells, including changes to the function and expression of APP components resulting in a reduction/loss of MHC-I at the cell surface, a common feature observed in many cancers. The loss of MHC-I influences levels of infiltrating T-cells and response to checkpoint inhibitor immunotherapy. Whilst studies have investigated the functionality of T-cells in resistance to immunotherapy, few have characterised the role of APP on T-cell responses and treatment success/failure. This project aims to establish a patient-derived tumour organoid (PDO) T-cell co-culture system from HPV+ oropharyngeal squamous cell carcinoma to replace the use of mice in characterising the impact of APP on anti-tumour T-cell responses. Our objectives are to 1) establish a robust methodology for the PDO co-culture system and functional assessment of T-cell responses, 2) characterise APP mechanism in each PDO by determining the expression and mutation profile of key components, the cell surface expression of MHC-I and anti-tumour T-cell function, 3) modulation of APP with specific inhibitors/activators, and how this impacts on T-cell responses and immunotherapy efficacy. This model will be essential for replacing the current use of mice and provide a more relevant/better understanding of the contribution of APP alterations on effective T-cell responses in cancer. It will provide key knowledge on how to improve MHC-I antigen presentation in a patient-specific manner, how this influences the response to immunotherapy, as well as the potential to identify patients who are likely to benefit from immunotherapy with the addition of APP modulation. Furthermore, once established, this model system will provide a key tool for researchers investigating specific APP components in disease (cancer, viral infection and autoimmunity), as well as being adopted for other cancer systems, giving rise to patient specific understanding on how antigen processing and presentation influences T-cell responses in these systems.