Applications of tumour specific T-cells in adoptive immunotherapy of cancer

Abstract

The underlying concept of cancer immunotherapy is the modulation of immune mechanisms to drive effective anti-tumour responses. Adoptive cell transfer (ACT) is a form of cancer immunotherapy based on the generation and expansion of tumour-reactive lymphocytes and their administration to a lymphodepleted patient in combination with interleukin-2 (IL-2). To date, ACT has achieved encouraging results in cancer patients in non-randomised clinical trials and much effort is being directed to further increase the clinical success rate of this modality of treatment. This study sought to investigate some of the key aspects of the biology of tumour-directed T-cells in order to understand how the protocols of ACT may be further improved. To do so, two approaches for the generation of tumour-specific T-cells were studied. First, tumour infiltrating lymphocytes (TILs) were generated from melanoma tumours. TILs were successfully cultured from almost 90% of the patients from which tumour samples were collected. These cells comprised predominantly CD8+ cytotoxic T-cells of a late-differentiated phenotype. Only TILs cultured from 3 patients showed some anti-tumour reactivity with autologous tumour cells; plus, histological analysis of tumour samples revealed the presence of some negative regulators of T-cell function in situ. The second approach consisted in the generation of tumour reactive T-cells by gene transfer to peripheral blood lymphocytes of a highly avid melanoma specific (MART-1 antigen specific) T-cell receptor (TCR) restricted to HLA-A2 recognition. These genetically modified T-cells recognised and killed tumour cells in vitro and in vivo using mouse models of adoptive cell transfer. Moreover, a novel dynamics of T-cell proliferation was observed after introducing this highly avid TCR into T-cells. In addition, functionally early-differentiated anti-tumour T-cells were generated by culturing genetically modified T-cells in the presence of the common-γc cytokines IL-7 and IL-15. These cytokines also had a significant positive effect on the proliferation and viability of T-cells as compared to the extensively used IL-2. Likewise, IL-21, IL-6 and IL-12 were found to generate potent anti-tumour T-cells, although compromised cell viability may be an issue. Furthermore, the functional and phenotypic properties of engineered anti-tumour T-cells derived from different subsets of memory T-cells were also investigated. In vitro, genetically modified T-cells derived from naïve and central memory T-cells based on CCR7, but not CD62L expression, performed as an early differentiated population of T-cells and preserved to a greater extent the expression of markers of 'young' T-cells compared to anti-tumour lymphocytes derived from late differentiated T-cells including effector memory and purely effector T-cells. In summary, this thesis highlights some of the most important aspects of T-cell biology related to the successful application of T-cell-based immunotherapy and suggests future avenues for improved forms of cancer treatment

Date of Award	1 Aug 2011
Original language	English
Awarding Institution	The University of Manchester
Supervisor	David Gilham (Supervisor)