We tend to think of viruses as disease harbingers. Oncology researchers have found however that some viruses can be modified in the laboratory to infect and kill Cancer tumour cells while not harming healthy cells.
A small but growing number of patients are benefiting from this new-targeted but presently exceedingly expensive viral treatment approach.
After a decade of research, the US Food and Drug Administration, (FDA), and the European Medicines Agency approved T-VEC in 2015. This is an oncolytic virus modification based on the herpes virus and approval followed successful phase III multi-centre clinical trials on patients suffering from metastasic skin cancer. It was later given the green light by the NHS in UK for use on patients with inoperable malignant melanoma. Skin cancer that is now the fifth most common cancer in UK, with more than 14,500 diagnosed each year.
Oncolytic viruses, (OVs), used in virotherapy can not only kill cancer cells, but also trigger an immune response in the body against cancer. When a virus infects a tumour cell, the virus makes copies of itself until the cell bursts. The dying cancer cell releases toxic tumour antigens. These alert the body’s immune system and stimulate it to respond to the danger, not only from nearby cancer cells in the primary cancer site but of those that have migrated to other parts of the body in a secondary malignant metastatic growth.
These are still early days in oncolytic viral research and immunotherapy. But many more studies and clinical trials are underway across the world. They will provide insights into oncolytic virus use in combination therapies that not only kill cancer cells, but also enhance the body’s immune response to promote antitumour immunity.
Human Gene Therapy
Photo Credit: National Cancer Institute