Medical Biology - Theses
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ItemNo Preview AvailableEngineering Chimeric Antigen Receptor T Cell Therapy for GlioblastomaAbbott, Rebecca Caitlyn ( 2022)Glioblastoma is a highly aggressive form of brain malignancy which primarily affects adults, but cases do also arise in children. The current standard of care for glioblastoma; the Stupp protocol, consists of debulking surgery, chemotherapy and radiotherapy. However, the treatment is highly unlikely to be curative and tumours commonly relapse. The current lack of effective treatments for glioblastoma highlights the need for the development of precision therapies. The immune system possesses a natural capability to protect the body and the anti-tumour functionality of T cells has been harnessed in the development of novel treatments. Chimeric Antigen Receptor (CAR) T cells express a synthetic cell surface receptor specific for a tumour-expressed antigen. These cells can then exert cytotoxic and cytokine-producing functions directed towards tumour cells. In a subset of glioblastoma patients, the Epidermal Growth Factor Receptor (EGFR) protein is truncated, generating an exquisitely tumour-specific mutation (EGFRvIII) to target with precision-based medicines. In this thesis, a novel CAR targeting this protein; GCT02, was characterised in primary murine and human T cells. The prediction of the binding epitope indicated GCT02 to bind to amino acids in a shared region between the EGFR and EGFRvIII proteins. Despite this, the CAR demonstrated functional specificity to cells expressing EGFRvIII in both the murine and human systems in vitro. In vivo, a single infusion of the GCT02 CAR T cells mediated the clearance of implanted orthotopic glioblastoma tumours within one month post T cell infusion. The CAR T cells were unreactive to primary human EGFR+ keratinocytes and astrocytes, suggesting a favourable safety profile. Unfortunately, the clinical evaluation of EGFRvIII specific CAR T cells has led to disappointing anti-tumour efficacy. Consequently, this thesis also investigated the re-utilisation of the GCT02 binding domain into a synthetic Notch receptor, employing logic gating technology. The system is designed to restrict the induced secretion of anti-tumour factors to within the tumour site, limiting systemic toxicity. Unfortunately, whilst the constructs could be generated and highly expressed in the Jurkat human T cell line, the circuit failed to activate in the presence of an EGFRvIII stimulus. The work in this thesis has directly contributed to the establishment of the CAR T cell development pipeline in the Jenkins Laboratory whilst characterising a novel, high affinity antigen binding domain which shows efficacy in a CAR format and may also have further clinical applications given the favourable safety profile.