MICA: Upregulation of innate immunity in the tumour microenvironment of oesophageal cancer using oncolytic virus therapy with immunotherapy

Oesophageal cancer is a highly aggressive cancer with five year survival rates of 15%. There are two main subtypes, squamous cell cancer and adenocarcinoma. This study is focussed on Oesophageal Adenocarcinoma as it is the commonest form in the UK. Current treatment uses chemotherapy and/or radiotherapy prior to surgery to try to cure the disease. Despite advances in these treatments there has still been no significant change in patients' outcomes. Immunotherapy opens the door to changing these results. So far, we have seen very good responses in other cancers, such as melanoma, and head and neck cancer, however results in Oesophageal cancer have been relatively disappointing. We are looking to increase our understanding of the immune reaction that occurs in Oesophageal cancer and how we can improve this to benefit patients.

Using samples collected at surgery, we will use a cutting-edge imaging technique, multispectral immunohistochemistry, to examine the tumour microenvironment of Oesophageal Adenocarcinoma, specifically looking at the number and interactions of immune cells found within the tumour. We are hopeful that the knowledge that we gain from the first part of the study will allow us to identify which immune cell types we need to increase the activity of, so that our treatment will create an improved immune response to Oesophageal cancer. Our laboratory specialises in the use of oncolytic ("cancer killing") viruses to increase the immune reaction in tumours and so our second experiment will look to selectively infect and kill the tumour using an oncolytic virus whilst not affecting the normal oesophageal tissue.

We have designed a novel combination immunotherapy strategy which is given directly into the tumour itself which will augment the action of the oncolytic virus. This "intratumoural immunotherapy" uses the cancer as a vaccine against itself, meaning the immune system is activated to destroy the tumour that it was previously unable to fight. There are other advantages to intratumoural immunotherapy in that we can give higher doses of drugs, which since they are acting locally, cause fewer side effects. Once the immune system is trained to kill the primary tumour it should then hunt down disease elsewhere in the body without the need for further treatments. Our combination therapy utilises the oncolytic Herpes Simplex virus-1 (HSV-1) with a novel immune stimulating agent (IL-15 Superagonist, N-803) and an immune checkpoint blocker (anti-Programmed Death-1, anti-PD-1). N-803 has been shown to increase the levels of natural killer cells as well as effector T Cells (which both kill the cancer) in other tumours. Immune checkpoint blockers stop the mechanism by which many tumours inhibit these immune cells from destroying them and previous work has shown that this mechanism is upregulated after oncolytic virus infection.

We have setup a new collaboration with a research team based in Germany who have created the first mouse model of Oesophageal Adenocarcinoma in the world. This will allow us to test our immunotherapy strategy in mice. We will examine the effect that HSV-1 infection has on cells of mouse Oesophageal Adenocarcinoma. Then we will use our triple combination immunotherapy of - HSV-1, N-803 and anti-PD-1 antibody to treat Oesophageal tumours in mice. As all the agents used in this study have been safely used in patients previously, this combination intratumoural immunotherapy could be translated to a human clinical trial in the future.

Oesophageal cancer, of which adenocarcinoma (OAC) is the predominant subtype in the UK, ranks sixth among all cancers for mortality, with survival rates of ~15%. This provides a strong rationale for pursuing a combination of immunotherapeutic approaches that aim to activate those cell types integral for generating an immune response within the OAC tumour microenvironment (TME).

Our hypothesis is that intra-tumoural use of oncolytic herpes simplex virus-1 (HSV-1) will increase levels of Natural Killer (NK) cells that will control the levels of stimulatory Dendritic Cells in the TME, leading to recruitment of CD8+ effector T cells. Combining this treatment with a novel IL-15 superagonist/IL-15 receptor alpha fusion complex (N-803) will enhance the number and function of both NK cells and effector T-cells leading to increased responsiveness to immune checkpoint blockade.

Using samples collected at surgery, we will evaluate the immune cell types found within the OAC TME using our expertise in state-of-the-art multispectral immunohistochemistry. The frequency of these different cell types will be correlated to other factors related to the TME by RNA immune profiling. Alongside this we will use an ex-vivo oesophageal tumour slice culture system to assess HSV-1 infectivity of the human OAC using direct immunofluorescence.

The next stage of the project will utilise a transgenic mouse model of OAC. Initially, we will examine the effect that HSV-1 infection has on a mouse tumour organoid model. Then we will use a triple combination immunotherapy of: HSV-1, N-803 and anti-PD-1 antibody to induce tumour regression in the OAC mouse model. Data analysis will focus on quantitating immune cell types in treated versus untreated tumours, defining their anatomical locations and interactions. All the agents used in this study have been safely used in patients previously and so this combination intratumoural immunotherapy could be translated to a clinical trial in the future.