The Herpes simplex virus is a widespread virus that often causes cold sores, and most people carry it. By removing a virulence gene, i.e. a gene that makes the virus harmful to humans, the herpes virus can be repurposed as a cancer vaccine. This modification prevents the virus from harming healthy tissue while allowing it to target cancer cells, which function differently from normal cells. These findings are presented in a new doctoral thesis at Åbo Akademi University, Finland.
The new cancer vaccine includes a gene that encodes the protein decorin. Decorin is a proteoglycan—a protein with attached sugar chains—crucial for connective tissue, where it regulates wound healing and the formation of new blood vessels.
“Ample evidence shows that decorin is absent in most human cancers, even in tissues where it is normally present. Tumor angiogenesis—the formation of new blood vessels during tumor growth—leads to the development of disorganized vessels around the tumor. These disorganized blood vessels hinder drug delivery to the tumor and shield it from various therapies. They also contribute to more aggressive cancer,” says Ph.D. Fanny Frejborg, who is completing her doctoral thesis in pharmacy at Åbo Akademi University.
In the first part of her thesis, Frejborg demonstrated that decorin enhanced the vaccine’s cancer-killing effect on lung cancer cells. In the second part of the study, the research showed that these cancer vaccines can be administered intranasally to the lungs of mice.
In the third part of the study, the cancer vaccine was shown to reduce tumor angiogenesis by 40% in liver cancer in chicken embryos, with treated tumors developing normal blood vessels compared to untreated ones. This effect was observed even when tumors were treated after blood vessel formation and appeared just a few days after a single vaccine dose. The chicken embryos showed no side effects from the treatment, indicating that the vaccine’s action is specific to the tumor.
“These results could pave the way for new cancer vaccines that not only treat cancer without side effects, but also enhance the effectiveness of existing therapies, since regulating blood vessel growth around tumors can improve drug delivery,” says Frejborg.
More information:
Ph.D. Fanny Frejborg defended her doctoral thesis in pharmacy, titled “Decorin-expressing oncolytic herpes simplex virus vector for novel cancer therapy” on Friday, 19 . The thesis is available to read online: https://www.doria.fi/handle/10024/193197
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Abo Akademi University
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