An experimental treatment using a modified bird virus may hold promise for people with advanced malignant mesothelioma.
Fowlpox is a viral infection that primarily affects chickens and turkeys. It is caused by an avipoxvirus from the Poxviridae family. Recently, some of the world’s top mesothelioma researchers at the John A. Burns School of Medicine at the University of Hawaii used an altered form of the Fowlpox virus to successfully stimulate an anti-tumor immune response in mice with mesothelioma cancer.
The treatment focused on a protein called survivin which is overexpressed by most human cancers, including mesothelioma, but rarely found in healthy tissues. In an effort to jump-start the immune systems of lab mice into targeting and attacking survivin-producing mesothelioma cells, the scientists altered the Fowlpox virus so that it would encode for survivin. The mice were then vaccinated with the Fowlpox-based survivin vaccine. The results were what the research team had been hoping for.
“Vaccination generated significant immune responses in both models, leading to delayed tumor growth and improved animal survival,” wrote the authors in the summary of their findings in the International Journal of Cancer. The Fowlpox-based survivin vaccine triggered a significant increase in the number of cancer-fighting CD8(+) T cells, particularly those that were survivin-specific. Analyses of the mouse tumors showed that the T cells had infiltrated the tumors, effectively ‘waking up’ the cell-signaling proteins responsible for stimulating immune responses. The vaccination had no negative impact on fertility in the mice and did not inadvertently cause their immune systems to attack healthy tissues.
Mesothelioma is a cancer of the membranes surrounding the lungs or lining the abdomen for which there is currently no standard cure. It is caused almost exclusively by exposure to asbestos, a mineral once widely used in insulation, construction and manufacturing. Although asbestos use is now regulated in the U.S., the National Institute for Occupational Safety and Health (NIOSH) estimates that more than a million people are still working in job environments that put them at risk for mesothelioma.
Bertino, P, “Fowlpox-based survivin vaccination for malignant mesothelioma therapy”, January 21, 2012, International Journal of Cancer, Epub ahead of print.