Development and clinical translation of virus-specific T cell therapies for treatment of life-threatening viral diseases

Cooper, Rachel (2025) Development and clinical translation of virus-specific T cell therapies for treatment of life-threatening viral diseases. PhD thesis, University of Glasgow.

Abstract

Adoptive immunotherapy with virus-specific T cells (VST) has demonstrated clinical efficacy in restoring antiviral immunity in immunocompromised patients.

Epstein-Barr virus (EBV) is an extremely common herpesvirus (90% prevalence worldwide), that infects the majority of individuals during childhood or adolescence and thereafter establishes a lifelong latency in the host. In immunocompromised individuals, EBV can drive a malignant transformation of B cells due to the absence of circulating memory EBV-specific T cell surveillance. Transplant patients are particularly at risk of developing an aggressive EBV-induced lymphoma, and despite first line treatments the mortality rate remains high.

The Scottish National Blood Transfusion Service has been involved in adoptive EBV VST therapy of EBV-associated lymphomas for over 20 years. Initial EBV VST products were manufactured from healthy donor leukapheresis using repeated stimulations with EBV-infected lymphoblastoid cell lines to induce expansion of EBVspecific T cell clones. These therapies have treated over 200 patients with excellent safety and efficacy in tumour regression (>60% complete response rates). More recently, we developed a new manufacturing process by stimulating donor leukapheresis with EBV peptide pools, followed by isolation of responding memory EBV VST using cytokine capture selection, with further culture expansion. This study aimed to comprehensively compare EBV VST therapies manufactured from the two processes, with characterisation assays developed to assess quality, phenotype, functionality, migratory capacity and clonal repertoire of T cell products. Peptidederived VST demonstrated enhanced degranulation and cytokine production to a broad range of EBV latent antigens, as well as a dominant central memory phenotype, which may improve persistence and targeted tumour clearance in patients. Moreover, the peptide process had clear benefits in terms of process biosafety, reduced culture duration and massively higher yield of patient doses.

Furthermore, the emergent severe acute respiratory syndrome coronavirus-2 (SARSCoV-2) outbreak at the beginning of this study allowed us to investigate SARS-CoV-2 immune responses in individuals following natural resolution of primary infection. Natural killer cell frequency within peripheral blood mononuclear cells was significantly increased in individuals within 1-3 months convalescence compared to unexposed individuals. Convalescent donors had detectable CD4 and CD8 memory T cells populations to SARS-CoV-2 spike, nucleocapsid and membrane peptides whereas unexposed individuals showed no lymphocyte responses to the SARS-CoV-2 antigens. Interestingly, the frequency of SARS-CoV-2-specific T cells within the total T cell compartment decreased over time from symptoms resolution, indicating memory T cell responses of unvaccinated individuals after primary infection decline without antigen re-exposure. With detectable memory T cell populations, we were able to isolate SARS-CoV-2-specific T cells from donor blood using cytokine capture or T cell activation-induced marker selection. We further developed a culture protocol to rapidly expand a purified SARS-CoV-2 VST population with desirable central memory phenotype and broad SARS-CoV-2 antigen effector functionality. Given that disease severity has been associated with a reduced or dysfunctional T cell response, adoptive transfer of healthy donor SARS-CoV-2 VST may provide a potential treatment strategy. To this end, the peptide-mediated process developed for EBV was rapidly translated to manufacture an allogeneic bank of SARS-CoV-2 VST, with clinical products tested in a first-in-human trial for high-risk hospitalised patients.

The development and clinical manufacture of two T cell therapies targeting very different viral diseases required comprehensive analytical testing to understand the potential functional mechanisms of these cell products. The extensive suite of characterisation assays developed was used to build a profile for antigen-specific T cell therapies, in order to evaluate the optimal characteristics for clinical efficacy.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QR Microbiology > QR180 Immunology; Q Science > QR Microbiology > QR355 Virology
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Infection & Immunity
• Supervisor's Name: Fraser, Dr. Alasdair and Gerard, Professor Graham
• Date of Award: 2025
• Depositing User: Theses Team
• Unique ID: glathesis:2025-85627
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 06 Jan 2026 16:38
• Last Modified: 06 Jan 2026 16:46
• Thesis DOI: 10.5525/gla.thesis.85627
• URI: https://theses.gla.ac.uk/id/eprint/85627

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