Attempts to use genetically modified viruses to destroy malignant tumors are increasingly encouraging. Jason Chesney of the University of Louisville says that in some patients they caused the advanced melanoma to regress.
This was reported at the 51st Congress of the American Society of Clinical Oncology (ASCO), which ended in Chicago on Tuesday. A publication on this subject also appeared in the latest issue of the Journal of Clinical Oncology.
Jason Chesney, together with Robert Coffin, has been researching the use of a modified herpes virus called T-VEC, which does not cause infection, but can penetrate and destroy melanoma and skin cancer cells. They presented the first reports of this at the two previous ASCO conferences (in 2013 and 2014).
The latest publication shows that the research has so far covered 436 people with advanced melanoma in 64 centers around the world, mainly in the USA. Patients were injected with a dose of modified viruses every two weeks. Not all responded to treatment, but 16 percent. patients obtained 50 percent. disease remission which lasted for at least six months.
The best results were obtained in people with slightly less advanced melanoma and in those who had not been treated with other methods before. The average survival time in this group was 20 months longer than in patients who were not treated with the anti-cancer vaccine. Thanks to the new method, patients lived on average 41 months, while those who were treated with traditional methods only 21,5 months.
Coffin, who developed the anti-cancer vaccine T-VEC, says that some patients achieved significantly longer remissions of the disease despite the advancement of the disease. Some of them have been living for over 3 years. One of these patients is Shari Wells Ashland, 56, in the US, who entered clinical trials in 2010 when her melanoma was in her fourth stage of development. When she checked into the Graham Brown Center at Louisville University Hospital, she was only given six months to live.
Dr Chesney explains that the herpes T-VEC viruses fight melanoma in two ways: they penetrate the cancer cells and literally burst them from the inside while stimulating the immune system.
Viruses enter cells to reproduce in them, and when a new army of these germs is formed, the infected cell is destroyed. New generations of viruses penetrate new cells, in this case cancerous cells, leading to their destruction. They do it by destroying them directly, causing them to rupture, or by causing the so-called apoptosis, i.e. cell suicide.
When the infected cancer cells break down, they release antigens that have been smuggled into the herpes virus, which in turn triggers an immune response. They are intercepted by dendritic cells, then they are shown to T-lymphocytes, which better recognize the cancer cells hiding in the patient’s body. By the way, NK lymphocytes are activated, which can destroy them.
Modified viruses that cause these reactions are called oncolytic viruses. They are being used to treat several other malignancies, such as head and neck cancer and liver cancer. In addition to the herpes virus, these studies use, inter alia, vesicular stomatitis microbes.
This new method of immunotherapy is expected to be approved for use by the U.S. Food and Drug Administration (FDA) within a few years. Coffin says it can be combined with other immunotherapy treatments that have recently been approved in the US and Europe.