Enhanced Dendritic Cell Immunology for Glioblastoma

Glioblastoma Multiforme(GBM) is a highly malignant brain tumour with many patients surviving less that a year. Even with maximum surgery, chemotherapy and radiotherapy less than half of patients will survive 2 years and only 6% will be alive at 5 years. Therefore there is an urgent need for new treatments. Boosting the immune system's natural ability to fight cancer using dendritic cells has shown promise in some patients. Dendritic cells (DC) are particular white cells which mobilise other immune cells (killer T-cells) to recognise and kill cancer cells. DC can be made in a laboratory using a patient's own white cells (monocyte derived DC, moDC) and then stimulated with the patient's own cancer removed at surgery. These DCs are injected back into the patients to boost the immune system (DC Vaccination). Phase I/II trials have shown this approach is very useful in some patients, allowing patients to live significantly longer than predicted, but for many the effect is limited. More research is needed to make these promising treatments more effective in more patients.
Our proposal aims is to increase the effectiveness of current DC vaccines, to test potentially even more effective DC approaches and examine combinations with other treatments that boost the immune system. We will do this this by:

1. Enhancing the function of DC by blocking specific signalling pathways:
Cancer is able to suppress the immune system, and in particular can suppress the important functions of DCs. We and other have found specific signalling pathways within the DC by which cancer can do this and have shown that specific drugs can block these and restore DC function. We will apply this knowledge to improve current DC therapy against GBM. Using DC from healthy donors and GBM patients and using GBM cell lines and tumour removed at operation, we will test how well the pathway blocking drugs enhance DC function.

2. Compare circulating DC populations with the current laboratory generated moDC and test feasibility for use in vaccines:
DCs circulating naturally in the blood have favourable characteristics compared to moDC, generated in the laboratory, and are potentially more potent as DC vaccines. I will test this in relation to GBM and will test whether these can be enhanced in the same way as moDC. In preliminary experiments I have shown that circulating DC are reduced in GBM patients compared to healthy people, however modern techniques allow isolation of small numbers of cells for use as vaccines. In this proposal I will test whether one can actually prepare a vaccine from circulating DCs in GBM. This is very important because, in addition to potentially being better vaccines, these DC do not need culture in a specialised laboratory and so treatments may be more accessible to more patients.

3. Combine DC therapy and Checkpoint blockade:
A new class of anti cancer drugs, that 'release the brakes' on the immune system (checkpoint blockade) have shown very promising results in a range of cancers. Using experimental systems already established in our laboratories, we will combine our enhanced DCs, which 'turn on' T cells and checkpoint blockade drugs which 'take the brakes off' the T cell, and test if we can produce even more effective anti-cancer T-cells.

If our experiments are successful, we expect these finding to be incorporated very quickly into the next generation of clinical trials and so potentially giving patient benefit over the next five years. This will be facilitated by our collaborators who have on going DC vaccine clinical programmes. Our aim being a treatment which prolongs survival, with little toxicity and improved quality of life for GBM patients. The ability to target DC function and so modify immnue responses has implications for other areas of immunology such as autoimmunity and infectious diseases. We also envisage that our finding can be extrapolated to other cancers with similar benefits.

BACKGROUND: Glioblastoma (GBM) survival is poor with a median of 14.6 months despite maximum radical therapy. Dendritic cell vaccination in GBM using adoptive transfer of monocyte derived DC (moDC) loaded with autologous tumour lysate, is an safe treatment strategy in early phase trials but with modest efficacy.
AIMS:

(1) Enhance DC function by inhibiting specific intracellular signalling pathways
(2) Establish feasibility of adoptive transfer of circulating DC for clinical
(3) Combine DC immunotherapy with immunological checkpoint blockade.

METHOD: In-vitro created moDC and freshly-isolated CD1c+ mDC1 will be isolated from patients and healthy controls then pulsed with tumour lysate from GBM cell lines or autologous tumour. DC function will be assessed by cytokine profile, phenotype, chemotaxis and T-cell assays. The capacity of small molecule inhibitors (e.g. BIRB0796 for p38 MAPK, AG10 for STAT3) to enhance DC function will then be determined. Lastly the effect of combining enhanced DC with checkpoint blockade will be investigated using ELIspot and cytotoxicity assays.

OPPORTUNITIES: This project will unveil opportunities to understand and restore DC and T-cell function in patients with GBM by understanding and targeting disrupted intracellular signalling pathways. Importantly, the combination of enhanced DC vaccines with checkpoint blockade will reveal potentially novel therapeutic avenues. The expansion of our international collaborations are key to achieving these goals and will pave the way for the applications of these approaches to the management of other malignancies. This study has clear implications for the understanding of autoimmune and infectious disease pathology.

Brain tumours are the biggest cancer killer of children and adults under 40. Glioblastoma Multiforme(GBM) has a median survival of less than 15 months even with maximum therapy. For such poor survival the high risk surgery and toxicity from prolonged chemotherapy and radiotherapy offer little hope for patients. Unfortunately GBM has two peak incidences in the 0-8 years and 50-70 years age group. The location of the tumour results in neurological deficit and disability. The economic burden of life years lost in children, young adults and older adults to the UK economy is huge. Likewise the care costs and damaging economic cost on the surrounding family with either the loss of the main earner and/or family member becoming a carer are substantial.

The main beneficiaries of our research if successful will be patients and carers. Enhanced DC vaccination offers real potential for increasing survival and also reducing morbidity. Furthermore toxicity associated with treatment is likely to be reduced. Recent developments in immunotherapy in other cancers with checkpoint blockade has given real hope of long term disease control. We envisage our research will contribute to such development in Glioblastoma. The results of our research could be in clinic trials within 3 years, as several of the small molecule inhibitors of signal transduction are already in clinical uses. In addition the network of collaborators have a programme and infrastructure that would facilitate the incorporation of our findings into clinical protocols.

This project will provide direct benefit with technology transfer between ourselves and the collaborating centres. We will share our expertise in measuring rare circulating DC populations, signal transduction inhibition and use of checkpoint inhibitors in the clinic enhancing their research. In return we will acquire expertise in clinical DC vaccination preparation. The mixed skill set of both adult and paediatric oncologists will also mean our work and clinical network approach benefits all age groups. Currently in the UK there are very few centres that can offer DC immunotherapy and we hope to open a center in Nottingham for preparing DC vaccines.

The use of DCs has also been investigated in other cancers. Our findings will potentially be applicable to other cancers. Indeed the results of checkpoint blockade with other vaccine approaches is already being investigated in other cancer types.

As DC vaccines and checkpoint inhibitors are already in clinical use in other cancers, our findings could be incorporated into clinical studies relatively rapidly.

The suppression of DC, resulting in similar signalling pathway disturbance is also seen in infectious disease and the principles applied in our approach could be investigated in infectious disease models.
The ability to modify T cell subsets by manipulating intracellular signalling in DCs has potential therapeutic use in autoimmune diseases such as Rheumatoid arthritis, Inflammatory bowel disease and Multiple sclerosis, where T cell differentiation may be perturbed. By delineating the relative importance of the intracellular signalling pathways on DC cytokine secretion we would hope to inform immunologists in these fields as to potential targets that may give immune suppressive effects.
The identification of new targets has potential for drug development, which will be of interest for both academic communities but also the biotechnology industry. By way of trying to estimate this commercial potential, ipilimimab, the first immunotherapy licenced in the last 20 years in the relative rare indication of metatstaic melanoma, had sales of $706 million in 2012.