Could a Virus treatment designed by Boston researchers be the key to treating the aggressive brain cancer glioblastoma?

Brigham and Women’s Hospital scientists report that they have created a cancer-attacking virus that can effectively target glioblastoma. The oncolytic virus treatment extended survival for patients with recurrent glioblastoma, especially among patients with pre-existing viral antibodies.

The virus can infect cancer cells and stimulate an anti-tumor Immune Response, according to the researchers.

“Almost no immunotherapies for GBM have been able to increase immune infiltration to these tumors, but the virus studied here provoked a very reactive immune response with infiltration of tumor-killing T-cells,” said corresponding author E. Antonio Chiocca, chair of the BWH Department of Neurosurgery.

“That’s hard to do with GBM, so our findings are exciting and give us hope for our next steps,” Chiocca added.

This Phase I, first-in-human trial looked at the safety of an oncolytic herpes simplex virus called CAN-3110. The cancer-attacking virus is the same type of virus used in a therapy for the treatment of metastatic melanoma.

Overall, the trial showed the safety of CAN-3110 in 41 patients with high-grade gliomas, including 32 with recurrent GBM. The most serious adverse events were seizures in two patients.

Notably, GBM patients who had pre-existing antibodies to the HSV1 virus (66% of the patients) had a median overall survival of 14.2 months.

The researchers believe that the presence of HSV1 antibodies sparked a rapid immune response to the virus — which brought more immune cells to the tumor and increased the levels of inflammation in the tumor microenvironment.

“GBM has an aggressive effect in part because of a milieu of immunosuppressive factors surrounding the tumor, which enable the tumor’s growth by preventing the immune system from entering and attacking it,” Chiocca said. “This study showed that with a virus we designed, we can reshape this ‘immune desert’ into a pro-inflammatory environment.”

Moving forward, the researchers plan to complete prospective studies to further investigate the effectiveness of the oncolytic virus in patients who do and do not have antibodies to HSV1.

After showing the safety of one viral injection, the scientists will be testing the safety and efficacy of up to six injections over four months — which, like multiple rounds of vaccination, may increase the effectiveness of the therapy.