According to researchers, genetically altered poliovirus strains could help some patients of brain cancer. A team of researchers used modified poliovirus strains in small groups of patients who had glioblastoma – a particularly deadly form of brain cancer. In these patients, standard treatments have failed to say the researchers and this novel therapy could help. The results of the study were published in the New England Journal of Medicine.
Dr. Darell Bigner, the director emeritus of The Preston Robert Tisch Brain Tumor Center at the Duke Cancer Institute says that he has been working on this for the last five decades and the results have been unique.
The research, however, is still rudimentary says Annick Desjardins, a neuro-oncologist, who was part of the study, and may take further studies and detailed understanding to be accepted as part of standard therapy. As of now treatment with these modified polioviruses resulted in prolonged survival in 21% of the study population.
Desjardins said that there have been long-term survivors and this is something that has not been seen among patients with glioblastoma. Glioblastoma remains one of the most common and aggressive forms of brain cancers in adults.
For this study, the team of researchers used the polio virus as it has the capacity to infect the nerve cells of the body. The poliovirus can cause lifelong paralysis when it infects children, but the version that the researchers used was a genetically modified one.
The modification involved removal of one of the genes of the virus that prevented it from causing polio. This gene was replaced by another harmless one derived from rhinovirus that causes the common cold.
This modified virus now was infused into the tumors of the patient’s brains directly with the help of a tube inserted into the skull. The virus not only killed the tumor cells in the patients’ brains but also stimulates the patients’ immune system that could attack the tumors. They involved 61 patients between 2012 and 2017 in whom different doses of the modified viruses were given.
Benefits of the virus on the tumors
Despite the benefits of the virus on the tumors and survival, it was not free of side effects and risks. There were cases of swelling in the brain that led to seizures and complications in the patients.
One of the patients also developed a blood clot within the brain that necessitated surgery. However, the overall medial survival was 12.5 months among those given polioviruses compared to 11.3 months in the past who had not been treated with any such therapy.
After 24 months from therapy, 21% of the virus-treated group survived when compared to 14% who had not been treated with any such therapy. This control group not treated with virus therapy was obtained from historical reports.
At 36 months after the treatment, 21% of the virus treated patients remained compared to only 4% in the control group. Two of the patients survived for over six years and one survived for over five years said Bigner. He said that this is something that has not been seen before.
Desjardins said that just like other immunotherapies this viral therapy does not work on all patients. However, if a patient responds, he or she is likely to be a long term survivor, Desjardins said.
As a next step says Bigner, the team wants to try the viral therapy on children with brain cancer as well as other cancers such as breast cancer and melanomas. At present Desjardins and some of the researchers hold patents for the treatment that the Duke licensed to Istari Oncology, a start up company. A phase 2 study is to start soon.