Oncolytic viruses have been getting more attention in the news lately due to some recent discoveries and a number of clinical trials underway.

  • The FDA Advisory Committee’s recent recommendation for the approval of Amgen’s virus-based T-VEC drug for melanoma.
  • CBS’ 60 Minutes mentioned Oncolytics brought attention to virus-based cancer treatments in a report focused on an engineered polio virus being developed to treat glioblastoma.

What exactly is an oncolytic virus?

An oncolytic virus is a virus that can infect and selectively destroy cancer cells; onco means cancer, lytic means that cells burst open and die.

The history of oncolytic viruses

The idea behind using viruses to fight cancer came about over a century ago. In 1904 a woman in Italy was diagnosed with uterine cancer and, after being bitten by a dog and given the rabies vaccine, her tumour seemed to disappear. This phenomenon piqued the interest of her doctor, who experimented by delivering weakened forms of the rabies viruses to other cancer patients, in the hope of a cure. While some of these cancer patients also had their tumours shrink, these patients eventually saw their cancers relapse. However, a new area of scientific study was sparked: oncolytic viruses.

In the past century, a wide range of viruses have been studied as possible cancer treatments: adenovirus, reovirus, measles, herpes simplex, Newcastle disease virus and vaccinia. However, unlike today, the technology to produce these viruses did not yet exist. So, as chemotherapy and radiotherapy were making huge strides in the treatment of cancer, the idea of using viruses to fight cancer was put on the backburner in favour of these more promising alternatives.

Oncolytic viruses today

Today there are many cancers that have not seen significant standard of care improvements in over 40 years. This brings to light the need to continue to look for new ways to fight cancer, especially as we learn more about how there are many different types of cancer cells that mutate and grow in different ways.

Oncolytics has been studying the cancer treatment potential of the reovirus, which is a common virus widely found in the environment. Research by our Chief Operating Officer, Dr. Matt Coffey, explored the ability of the reovirus to infect and selectively destroy cancer cells. These discoveries lead to the creation of our product, REOLYSIN®, which is a proprietary variant of the reovirus.

When a normal cell is infected with the reovirus, an antiviral response is activated, which prevents the virus from replicating within the cell. However, inside a cancer cell with one or more mutations on a growth pathway called the Ras pathway, there is an aberrant antiviral response that is unable to prevent the virus from replicating. This abnormality allows the reovirus to multiply to an extent that is fatal to the cancer cell.

To learn more about this process, check out our REOLYSIN® mechanism of action (MOA) video.

And, follow us on Twitter for more news on the progress being made with oncolytic viruses.