Surgical Viral Trials

Could Change Standard of Care for Glioblastoma

Glioblastoma is the most aggressive type of brain tumour and, unfortunately, most patients have a poor prognosis. Traditional chemotherapies are not effective for brain cancers, as the blood brain barrier prevents the drug from reaching the tumour. But two new surgical viral trials at Princess Margaret Cancer Centre are showing promise that could help to change the standard of care. Dr. Gelareh Zadeh, Head of Surgical Oncology at The Princess Margaret, is heading up the trials with Dr. Farshad Nassiri, Neurosurgery Resident and PhD candidate.

The first trial, Tocagen, is for patients who are undergoing a second operation for removal of their tumour. Following surgery, a modified virus containing a special enzyme is injected directly into the cavity to selectively infect tumour cells without infecting the brain. The patient then ingests a pill containing non-harmful medication. Tumour cells that contain the special enzyme convert the medication in the pill into a strong chemotherapeutic agent. This induces a significant immune and inflammatory reaction, which attacks the cancer cells.

“My hope is that through showing benefit in [recurring tumours] we can actually move on to introducing the surgical injection of viruses into the tumour cavity early at first diagnosis. That would change the standard of care for how we manage patients with glioblastoma,” says Dr. Zadeh.

The second trial, DNATrix, is for tumours where surgery is not possible. In this trial, a modified virus that induces a significant immune and inflammatory reaction to eradicate the tumour is injected directly into the tumour using a computer-enhanced navigation system. The Princess Margaret is the leading site for recruitment in this Phase 1 trial.

“There have been a few patients who have had very good results with the trial where we inject the modified virus. We hope to induce an inflammatory reaction to be able to attack the tumour cells. We've seen some amazing results on the imaging,” says Dr. Nassiri.