Using organotypic tumour slices to optimise 5T4 CAR-T cell therapy for pancreatic ductal adenocarcinoma

Thesis

Pancreatic ductal adenocarcinoma (PDAC) has a 5-year survival rate of less than 10%. This is due to a combination of limited treatment options, late diagnosis due to subtlety of symptoms, and frequent metastatic spread. Systemic control of disease can be achieved with chemotherapy, but chemotherapeutic resistance and dose-limiting toxicities frequently lead to disease recurrence. There are currently no licenced immunotherapies for PDAC, due to the dense desmoplastic stroma and immunosuppressive microenvironment. Whilst these parameters are central to the immune ‘cold’ nature of most PDAC tumours, they are not accurately represented by preclinical models.

Chimeric antigen receptor (CAR) T cell therapy has markedly improved the prognosis of multiple forms of haematological malignancy. Despite this success, no CAR-T cell therapies are currently licensed for use in solid tumours. Lack of tumour infiltration, antigen escape, local microenvironmental suppression, and difficulties identifying tumour specific antigens all contribute to the challenge of translating CAR-T cell therapy beyond haematological cancers.

Organotypic tumour slices allow these challenges to be addressed by preserving the cellular heterogeneity, soluble signalling and stromal structure of the native tumour. This thesis aims to use PDAC tumour slices to evaluate the efficacy of a novel CAR-T cell construct targeting the oncofoetal antigen 5T4. The expression of 5T4 across pancreatic tumours and PDAC cell lines was characterised, confirming the suitability of the target. Anti-5T4 CAR-T cells displayed selective and efficient cytotoxicity against 5T4+ cell lines in vitro along with high levels of IFNγ, granzyme B and IL-2 release. Autologous patient CAR-T cells were applied to tumour slices showing co-localisation with 5T4+ cells. The lack of cytotoxicity seen ex vivo prompted analysis of tumour slice-derived suppressive soluble factors and donor-specific T cell characteristics.

I demonstrate the utility of organotypic tumour slices in evaluating novel CAR-T cell therapies in a patient-relevant model prior to clinical trial.

Authors: Evans, A

• DOI: 10.5287/ora-r1o17y1ek
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: PDAC; preclinical model; pancreatic; immunotherapy; organotypic; CAR-T; oncology
• Subjects: Immunotherapy; Oncology