Cancer-fighting virus remodels tumours and synergizes with chemo and surgery in mice

With their fast metabolism, unchecked growth and remarkable ability to evade the immune system, cancer cells can present a juicy meal for a virus. Indeed, many viruses naturally replicate better in cancer cells than in normal cells – a phenomenon that underpins the development of oncolytic, or cancer-fighting viruses. 

Now, researchers at The Ottawa Hospital and the University of Ottawa have developed an oncolytic virus that not only preferentially attacks tumours, but also remodels tumours at the same time, making them more susceptible to viruses as well as other cancer therapies. 

The novel virus is based on a strain of vaccinia that has been safely used in vaccines. Dr. Stephen Boulton, a key member of the research team led by Dr. John Bell, engineered a virus to produce a natural protein called EPAC, which regulates cellular pathways important for cell growth, survival and migration.

As outlined in the Journal for ImmunoTherapy of Cancer, this viral therapy significantly improved survival in several mouse cancer models, including colorectal cancer and metastatic melanoma. The virus also worked synergistically with chemotherapy and surgery, showing greater anti-cancer activity than what would be expected by simply adding these therapies together. 

When the researchers examined virus-treated cancer cells under the microscope, they found that in addition to destroying the cancer cells directly, the virus caused the cells to merge into long tube-like structures. Virus infection also helped to activate the immune system to attack the tumour.

Importantly, the addition of EPAC didn’t increase viral replication in normal tissues or cause other side effects. 

“Viruses continue to provide exciting possibilities for the development of new cancer therapies,” said Dr. John Bell, senior scientist at The Ottawa Hospital and professor at the University of Ottawa. “Stephen’s work brings us closer to solutions that could make a big difference for patients.”