Translational development of oncolytic Newcastle Disease Virus for treatment of colorectal cancer

Cancer remains an important cause of morbidity and mortality despite the refinement of techniques used to manage the disease. Interventions like chemotherapy, radiotherapy and radical surgery can take patients to the limits of tolerable side effects in order to provide a modest survival advantage, particularity in advanced carcinomas. Immunotherapy is a different approach that aims to widen the margin between efficacy and tolerability of drugs and in some patients induce a full and lasting remission. Oncolytic viruses are an interesting emerging class of therapies that utilise vaccine-like viruses to replicate selectively within and destroy cancer cells whilst simultaneously stimulating the immune system. Cancer often evades the body's own attempt to reject disease tissue, by masking the immune system from recognising any evidence of abnormal cells and processes. However, when a cancer-selective virus begins to replicate in tumour cells and destroys them through a process called lysis, the resulting pro-inflammatory environment attracts the attention of the immune system the reality of the diseased tissue can be recognised.

The first example of a successful oncolytic virus cancer vaccine was approved recently for the treatment of metastatic melanoma, where the immune system, influenced by the virus was able to clear the disease in several of the patients who showed durable (and often ongoing) responses. The current proposal aims to build on this early development, using a powerful oncolytic virus vaccine (based on Newcastle Disease Virus, NDV) that should be even more capable of directing the immune system towards identifying and destroying cancer cells. Our approach will involve expressing cytokines, the messaging signals of the immune system, from the NDV oncolytic cancer vaccine in order to encourage a more robust immune response. In this way we hope to achieve efficacy in cancer indications that have have thus far been refractory to immunotherapy such as colorectal cancer. Although this project will address only the initial proof of concept stage, it will be conducted in a way that will enable future development and clinical trials.
We have structured the proposal as a strong and dynamic collaboration between established research groups in Malaysia and the UK. The Malaysian partner has world class expertise, and many years practical experience, in developing oncolytic viruses based upon NDV. The UK team has already developed an oncolytic virus based on adenovirus, successfully through preclinical studies to a series of clinical trials. The partnership proposed here will combine the key expertise form both centres in fostering rapid and ethical development of oncolytic NDV through basic scientific study, through preclinical development and will position it ready to enter clinical trial for colorectal cancer. In this way we aim to use the academic and translational strengths in both centres in creating a new therapeutic for potential treatment of this devastating disease.

The purpose of this project is to develop a new target-selective anticancer agent based on a tumour selective variant of the virulent Malaysian NDV AF2240 strain of Newcastle Disease Virus, and to position it ready for clinical trial in treatment of colorectal cancer. AF2240 was shown to have more potent tumour lysis characteristic relative to alternative isolates and vaccine strains currently available. The strain will be rendered inactive in avian cells by mutating the cleavage site of the fusion protein and .replacing the haemagglutination and neuraminidase (HN) gene of the virulent strain with a non-virulent strains. These virus will be assessed for lytic potency on a panel of human colorectal carcinoma cells and selectivity will be assessed by passaging 10 times in 9-to-11-day old SPF chicken embryonated eggs. These constructs will then be modified to express IL-12 and IL-15 in order to stimulate both adaptive and innate immune responses. Functional expression cytokines will be determined by activation of PBMCs in co-culture with NDV infected tumour cells in vivo and in colorectal xenografts in vivo. We will also establish activity in tumour associated stroma cells (such as activated fibroblasts) in 3D organotypic models. Finally, infection selectivity and immune cell stimulation will be characterised in fresh human tumour biopsies maintained in ex vivo culture. These studies will involve surgically removed waste tumour samples, together with normal margin tissue, maintained ex-vivo in the laboratory under local ethical approval. After exposure of tumour explants to NDV, cells will be disaggregated and evaluated by flow cytometry for evidence of virus mediated lysis (staining for viral coat protein, markers of apoptosis) and immune stimulation of resident leukocytes. Together these data should provide sufficient evidence of safety and efficacy for future development towards a clinical trial.

Who will benefit from this research?
Patients with advanced cancer: We intend that the main beneficiaries from this research will be cancer patients without effective treatment. We aim to develop the armed NDV to treat colorectal cancer (including both localised and metastatic forms) but expect it will be effective also against other types of cancer such as lung cancer. Virotherapy is characterised by two desirable features - very high selectivity for killing cancer cells (minimising systemic toxicities) and stimulation of the immune system to prevent cancer recurrence. Hence, if we are successful, we will develop a superior treatment for disseminated cancer that is both well tolerated and gives a high level of durable responses to a range of common cancers. This should have a major effect on quality of life for patients.

Healthcare services in the UK and in Malaysia: Some 37,000 new cases of cancer are diagnosed in Malaysia each year, and there are 22,000 cancer deaths. Total health expenditure for Malaysia in 2010 was 4.39 percent of GDP at RM 33.7 billion, lower than the average 6.1 percent expenditure for upper middle-income countries. Hence, the issue of affordability for cancer treatments is of major concern. This project will produce an armed Malaysian strain of NDV, providing a strategy for reduced cost cancer treatment. According to Prajuna Financial Advisors, Malaysia (2011), current cost of treatment for colorectal cancer is between RM 240,000 to RM 1.5 million per patient. In contrast, therapy with intravenous NDV (MTH-68/H strain) based on case reports on glioma patients at the Institute for Tumortherapy in Duderstadt, Germany, would cost 4200 Euros per shot (Nesselhut et al., 2011). This would translate to RM 18,126 per shot for a total of RM 362,520 over 5 years. In an earlier report, the Csatary Center for Virus therapy in Budapest, Hungary, treated patients with advanced cancers by inhalation of the live virus and the cost for a 2-3 week treatment ranges from USD 5000 to 6000 (RM 15,900 to 19,080) (Nelson, 1999).

Societal benefits worldwide: Cancer has a severe impact not only to individuals but also communities, significantly impacting family finances. In 2008, the top three cancers that caused the most economic impact globally were lung cancer (USD 188 billion), colon/rectum cancer (USD 99 billion) and breast cancer (USD 88 billion) (American Cancer Society, 2010). A summary of computations called a DALY (disability-adjusted life year) allows for an estimate on the burden of cancer. In 2008, estimated DALYs lost (millions USD) in the top three cancer sites were 14,833.7 (trachea/bronchus/lung), 854.8 (colon/rectum) and 846.1 (breast).

Scientists working in cancer immunotherapy and virotherapy: This field is developing quickly following granting of the first US product licence to Amgen. The work proposed here will be published in open access journals and also disseminated at scientific conferences by the investigators. In this way we aim to share our insights, following protection of any important intellectual property, and to maximise scientific insight and knowledge gain.

Potential corporate licensees and the local economy: There is currently a great deal of interest in commercialising novel immunotherapies based on oncolytic viruses. Our combination of expertise - Malaysian experts in oncolytic NDV and UK experts in translational development - provides a world class platform to develop and establish a new NDV-based clinical candidate technology. In Malaysia we have already had positive discussions with a range of potential licensees companies, including the Malaysian Biotech Corp and Malaysian Vaccine Pharmaceuticals (MVP). Many pharmaceutical companies worldwide are likely to be interested in this field, for example Medimmune have a particularly strong interest in oncolytic NDV vaccines, and we would be sure to keep them briefed of developments.