This fourth in our blog series on the progress of cell and gene therapy for cancer focuses on a treatment that has made huge strides in recent years: Viral Therapy.
What is Viral Therapy?
Using viruses to target disease is a science first contemplated over a hundred years ago, but was not possible until the technology advances we have now that enable genetic engineering. Oncolytic Viral Therapy [OV] made news last year at Duke University when a trial using a modified polio virus effectively destroyed Glioblastoma, a deadly brain cancer. Half the patients, in advanced stages, found themselves in remission. In other studies, a measles virus destroyed severe blood cancer and the maraba virus, related to rabies, reduced the size and spread of melanoma, lung and colon cancers, as well as select brain tumors.
How can a virus fight cancer?
You may be thinking: why would I purposely insert a virus into my body? Viruses are harmless once they are decoded, and there are over 3,500 known viruses with the potential to be therapeutic agents. In laboratory research, viruses proved their ability to spread curative agents rapidly in cancer cells and, at the same time, signal the immune system of a threat, so the body responds with its own army of killer T-cells.
ACGT and OV
Dr. John Bell, ACGT Scientific Advisory Council member, and Research Fellow, reported in April at the ACGT Scientific Symposium that viral therapy is a powerful 1-2 punch. “The virus attacks the tumor and the immune system comes in to finish the job.”
According to ACGT experts in the field, oncolytic viruses have an exemplary safety record. One of the greater success stories was a 49-year old patient at the end of a 10-year battle with myeloma who has been in remission for 2.5 years after the direct injection of a modified measles virus.
Dr. Bell and his colleagues at the forefront of OV describe viruses as “exquisitely selective” in targeting cancer cells and they are easily engineered to carry corrective genes to destroy or repair damaged genes.
Challenges and Potential
The great challenge ahead is to match the right virus to the cancer, as well as learn how to mass manufacture viral agents to treat large numbers of patients. Perhaps the greatest obstacle researchers face is that many tumors contain sensors that trigger an anti-viral response, to defend against the therapeutic influence of the virus. As we’ve reported before, cancer cells are tenacious in protecting themselves from interference from all types of treatment, including cell and gene therapies; however scientists are closing in on ways to destroy the cancer line of defense.
This science is moving rapidly. Researchers throughout the world are examining the intricate differences between types of cancers to ensure a virus’ ability to penetrate and replicate. At the same time, biotech and pharmaceutical firms are looking closely at the potential for this revolutionary treatment. Novartis, one of the largest drug companies in the world, is backing a therapy using an HIV virus with the hope of FDA approval within the year, and trials using Amgen’s Imlygic, an OV treatment for metastatic melanoma, used in combination with the chemotherapy drug Yervoy, improved life span. Stay tuned!
“There’s no question this field has altered the trajectory of cancer research – we’re moving towards a biologic approach and away from drug and radiation treatment.” Dr. John Bell, Ottawa Hospital Research Institute