Glioblastoma, a highly aggressive form of brain cancer, poses significant challenges to effective treatment and affects many Canadians each year. The standard treatment approach involves surgery and chemotherapy, but patients often face relapse and are left with limited treatment options.
To tackle this issue, a groundbreaking clinical trial was undertaken through a collaboration between the University Health Network (UHN) and the University of Toronto, spearheaded by Dr. Gelareh Zadeh — a neurosurgeon-scientist who serves as a professor in the department of surgery at the Temerty Faculty of Medicine. The trial’s results demonstrated the efficacy of a new therapy in significantly prolonging patient survival. The findings were published in the journal Nature Medicine.
This innovative therapy combines oncolytic viruses, specifically designed to infect and destroy cancer cells, with immune checkpoint inhibition — a type of targeted immunotherapy.
Immune checkpoint inhibitors are drugs that unleash the body’s immune response against cancer cells by blocking specific molecules or receptors that suppress immune activity. By removing these inhibitory signals, these inhibitors enable the immune system to recognize and attack cancer cells more effectively, potentially improving treatment outcomes.
While immune checkpoint inhibitors have proven effective against various cancers, their impact has been limited in the case of recurrent glioblastoma. This is primarily due to the immunologically inactive nature of glioblastomas, which renders these drugs ineffective. However, integrating oncolytic viruses can help create a more favourable tumour microenvironment, enhancing the immune response against the tumour. This two-pronged treatment strategy combines the local effect of the virus in the tumour and the systemic effect of checkpoint inhibition on the body’s immune response.
The treatment protocol involved injecting an engineered oncolytic virus into the tumour, utilizing minimally invasive techniques guided by advanced imaging technology. Additionally, a commonly used immune checkpoint inhibitor was administered intravenously every three weeks following the surgical procedure.
The trial included 49 patients with recurrent glioblastoma from 15 hospitals across North America. Notably, the median survival rate reached 12.5 months, surpassing the typical 6-8 month survival rate observed with current treatment approaches. Over 50% of the participants experienced significant clinical benefit from the treatment. Strikingly, some tumours even disappeared.
This study is the first to combine oncolytic viral therapy and immune checkpoint inhibitor for any brain tumour. With continued advancements in technology and a deeper understanding of glioblastoma biology, this innovative treatment approach will continue to evolve, leading to improved outcomes and ultimately offering a ray of hope for individuals affected by this devastating disease.
