Hong Kong researchers may have found a way to get around one of the biggest challenges of virotherapy for mesothelioma.
Virotherapy uses a modified virus to deliver medicine or genetic information into the body. Modified viruses are useful because they can be “programmed” to seek out cancer cells.
But modified viruses do not always behave the way scientists hope they will. One problem with some virotherapy for mesothelioma is that it can block the natural immune response.
The body naturally fights malignant mesothelioma by releasing white blood cells called CTLs (T lymphocytes). But MVTT virotherapy can prevent the release of CTLs, even while it attacks the tumor.
“Although MVTT [a type of virotherapy] leads to regression of established mesothelioma dose-dependently, antitumor CTLs are rarely induced,” writes lead study author Zhiwu Tan.
Viruses Need Help, Too
When it comes to fighting asbestos cancer, even a powerful virus-based drug needs help.
Many new cancer treatments focus on stimulating the immune system to join in the battle. But instead of recruiting more help, MVTT virotherapy can turn it away.
That is why the University of Hong Kong team says the best way to deliver virotherapy for mesothelioma is to combine it with an immune-stimulating strategy.
According the authors of a new paper, the strategy “results in the induction of potent antitumor CTLs that not only eradicate established mesothelioma but also prevent the second tumor challenge.”
This means that, if doctors can destroy the main mesothelioma tumor, it is less likely that new tumors will form.
Can Virotherapy Cure Mesothelioma?
Virotherapy is not a cure for mesothelioma. But combining virotherapy for mesothelioma with other therapies may improve survival.
In 2017, biologists in Minnesota showed how a certain kind of modified virus could make immunotherapy more effective.
This approach is called viroimmunotherapy. Immunotherapy drugs like Keytruda work by stimulating the immune system. In an article in Biomedicine, the researchers showed how certain viruses can sometimes do the same thing.
They suggested that these oncolytic viruses might enhance treatment for mesothelioma with Keytruda or other immunotherapy drugs.
Tan, Z, et al, “Virotherapy-recruited PMN-MDSC infiltration of mesothelioma blocks antitumor CTL by IL-10-mediated dendritic cell suppression”, October 16, 2018, Oncoimmunology, https://doi.org/10.1080/2162402X.2018.1518672