'T cell versus T cell': A Study of the Cellular Immune Response in Cutaneous T cell Lymphoma (CTCL)

Cutaneous T cell lymphomas (CTCL) are a group of malignant disorders derived from T lymphocytes, a type of white cell within our immune system. These malignant T cells settle mainly within the skin and cause severe complications. The rate at which the disease progresses within individual patients is variable but no genetic or phenotypic abnormalities of the tumour cell have been identified which determine disease progression. An alternative suggestion is that it is the patients' immune response to the tumour which regulates the aggressiveness of the disease.
There is currently a great deal of interest in how our immune system may act to prevent or control cancer. Indeed, many patients with diseases such as lung cancer are now achieving long term remission after injection of molecules called antibodies that boost the strength of the immune system. Interestingly, these drugs are believed to act by increasing the activity of T cells - the very cell that is the cause of cancer in patients with CTCL.
Evidence shows there is a cancer-specific immune response in patients with CTCL and in this fellowship we propose to investigate this in detail, in order to guide the introduction of new immune-based therapies. One fascinating aspect of the proposal is that we will examine how normal T cells are potentially able to control growth of malignant T cells. This will provide very novel information about the potential role of immune-modulatory therapy in patients with CTCL, which will be applicable to the treatment of cancer in general.
In order to carry out this work we will recruit patients from one of the largest CTCL clinical units in Europe, and blood and skin biopsies will be taken at different stages of disease. Malignant and reactive T cells will be isolated and examined by multi-parameter flow cytometry, including a complete analysis of co-stimulatory molecule expression. We will use antibody probes to determine the pattern of expression, on both malignant and normal T cells, of the molecules that can suppress normal immune function. One exciting aspect here is that we will have access to a new technology, CtTOF, which will allow us to determine the presence of up to 34 proteins on the surface of cells at the same time. We will also try to find molecules within the malignant T cells that act as the targets for the immune response. We will focus on cancer testis antigens (CTAg), a remarkable family of proteins that normally only expressed in germ cells such as testis or ovary, but which are also expressed in many cancers. Using reagents called tetramers we will investigate the presence of CTAg-reactive T cells and assess why they are not effective in patients with progressive disease. Finally we will culture healthy T cells isolated from within CTCL biopsies with the CTCL cancer cells themselves, to see if they can recognise and kill the tumour cells. We will then use investigate how we can block inhibitory signalling molecules to investigate how we can strengthen killing of the cancer.
We believe that we are strongly placed to perform this work as we bring together one of the largest and most academically active CTCL clinical units within the UK together with a very strong research team within tumour immunology. We anticipate that the results will contribute to a substantial increase in understanding of the mechanisms of immune evasion by CTCL.
This research programme will have direct relevance to the study of tumour immunology both within CTCL and in relation to other forms of cancer. The beneficiaries of the work will therefore include academics working within tumour immunology and a wide range of cancer physicians. Most importantly, we believe that it can be used to guide the introduction of immune-stimulatory antibody therapy through a personalised approach in patients with CTCL.

The clinical progression of cutaneous T cell lymphomas (CTCL) is heterogeneous but the disorder remains largely incurable. One factor that may determine outcome is the nature of the tumour-specific immune response. Several observations indicate that a CTCL-specific immune response can develop but is likely to be suppressed by several mechanisms of tumour evasion. Antibodies such as anti-PD1 or PDL1, which reverse T cell suppression by inhibitory co-stimulatory molecules, are effective in solid tumours and may be introduced in the management of CTCL. However CTCL represent a novel situation in that the tumour cells, being of haemopoietic origin, also express PD ligands.
In this fellowship I will undertake a detailed analysis of the reactive T cell infiltrate in patients with CTCL. The aims of the fellowship are to:-
- characterise the number, phenotype and functional properties of T cells within the tumour infiltrate of CTCL
- define the pattern of expression of co-stimulatory molecules such as PD1 and Tim3 on tumour infiltrating lymphocytes
- determine the antigenic specificity of the T cell infiltrate with particular focus on cancer-testis antigens (CTAg) and primary tumour cells
- correlate the functional activity of the reactive T cell infiltrate with clinical outcome.
Patients will be recruited from the supra-regional CTCL service and blood and skin biopsies taken at different stages of disease. Malignant and reactive T cells will be isolated and examined by multi-parameter flow cytometry, including a complete analysis of co-stimulatory molecule expression. HLA-peptide tetramers will determine the presence of T cells specific for CTAg, and co-cultures used to investigate recognition of tumour cells by the tumour infiltrate.
These results will lead to a substantial increase in understanding mechanisms of immune evasion by CTCL and can be used to guide the introduction of a stratified approach to immune-stimulatory antibody therapy.

In the UK, cancer is now the leading cause of death, accounting for 29% of deaths in 2013. Lymphoma is the most common form of haematological malignancy and cutaneous T cell lymphomas (CTCLs) are an incurable form which have a highly variable course. The disease can behave relatively indolently, responding well to cutaneous therapies, or it can be more aggressive causing significant morbidity and mortality. Differentiating between these forms of disease has proven difficult, and so far molecular research has not determined the pathological basis of this heterogeneity. The aims of this research are to understand how T cells interact with this form of cancer, and if variation in these interactions correlates with differences in clinical course. This could help with prognostic information for the disease, and could lead on to novel therapeutic strategies as is currently being trialled in other areas of oncology.

This research should be of great benefit to scientists working in the field of non-Hodgkin lymphoma. The object of our research is to characterise the immune response in CTCL, and demonstrate an important part of the 'hallmarks of cancer'. Our results should have implications, not just within CTCL, but also to other non-Hodgkin lymphoma, and haemato-oncology in general, improving our collective understanding of the pathological basis of disease in malignancy.

Such research could significantly benefit patients diagnosed with CTCL in the future. We are hoping to find indicators in the microenvironment of the tumour that would allow us to provide prognostic information on the disease. Prognostic information is one of the most important factors in determining the therapeutic approach to treatment, as well as being of psychological importance to the patient. At present it can be difficult to predict the phenotype of the disease, which is distressing for patients, and can mean that treatment decisions are made retrospectively based on the behaviour of the disease. Being able to differentiate between the phenotypes of disease may pave the way for patient-specific approaches using novel inhibitors of regulatory T cell antigens, and in this way provide benefit to both the informed patient and the clinician offering treatments.

Inhibitors of regulatory T cell antigens have been reported in the press as heralding a new breed of drugs in cancer treatment. Many pharmaceutical companies have developed PD-1 inhibition treatment, including Bristol-Myers, Merck, Roche, and the British-Swedish company AstraZeneca. As the immune response is thought to be crucial in cancer biology, the potential range of diseases these drugs could target is wide. Our research will help to determine if there is a scientific basis to pursuing PD-1 inhibition in this area, as well as demonstrating methods useful to investigating other haematological malignancies in similar ways.

In less direct terms, our research should play an international role in the scientific understanding of cancer. This will help raise the profile of scientific research in the UK, benefiting the image of the UK in science, and nurturing scientific and pharmaceutical research. We hope that our results will play a role in our understanding of cancer, and benefit the society as a whole by improving the health of our population, and contributing to the reasons the UK is a desirable place to live and work.