Share on PinterestScientists are trying to use viruses to fight cancerous tumors. DBenitostock/StocksyThe notion of using viruses to treat cancer is an old one. However, the use of genetically modified viruses to treat cancer began to be further investigated in the 1990s. Different viruses have different properties and the researchers are investigating the effect of different transgenes in this search.In a small trial that has not yet been published, a small number of patients with advanced cancers have seen their cancer progression stop or even be cured by a genetically modified version of the herpes virus.
Genetically engineering viruses to create an injection that can treat cancer is currently being pursued by several laboratories around the world.
Known as oncolytic viruses, these viruses replicate in cancer cells, rather than healthy cells, and then kill them by bursting them. When the cells burst, they release tumor antigens and proteins that the body recognizes as foreign, which then activates the immune system to attack the tumor cells.
Not only does this kill cancer cells, but it can also help reduce cancer recurrence, as the immune system now recognizes these antigens and protein biomarkers and knows how to attack the cells that contain them.
Oncolytic viruses have natural anticancer properties and additional properties thanks to genetic engineering to include genes that have an immune effect. Viruses that have been used as oncolytic viruses include herpes simplex virus, adenovirus, smallpox virus, and Coxsackie virus, with genetic modification used to introduce transgenes to improve their ability to kill cancer cells.
The first oncolytic virus therapy, T-VEC, which is based on the herpes simplex virus, was approved by the FDA in 2015 after a phase III trial showed it was effective against melanoma.
Scientists are also exploring other oncolytic viruses such as Vaxinia, a genetically modified smallpox vaccine virus designed for use with any type of cancer, which entered a Phase 1 clinical trial following promising results in animal models in June. 2022.
More recently, researchers from the Institute of Cancer Research announced the results of the first part of a phase 1 trial of an injection based on a genetically modified herpes virus, known as RP2, at the Congress of the European Society for Medical Oncology ( ESMO) 2022., London, and the Royal Marsden NHS Foundation Trust.
The test had been financed by the company that produces RP2.
Dr. Grant McFadden, director of the Biodesign Center for Immunotherapy, Vaccines and Virotherapy at Arizona State University, who is currently working on a cancer treatment using the myxoma virus, explained to Medical News Today that the information provided by this Human testing was useful, as it was difficult to obtain information on the effect of the body’s immune response from animal models.
“There are really two phases with oncolytic virotherapy. The first phase is the virus that infects and kills cancer cells. But that is only the first phase. If that’s the only thing that happens, you’ll never be able to kill the cancer cells and they’ll always come back,” he said.
“The second phase is the immune system that responds to the virus infection of the tumor cells. And the goal is for the immune system to see not only the virus, but also what we call tumor antigens that have been exposed by the replication of the virus in the tumor cell. But when both things happen, there is a chance of long-term regression of the cancer even after the immune response has cleared the virus. So it is that this second immune phase is very critical for long-term tumor aggression”, he further explained.
“And that phase is unique to people in the human immune system systems. This is why we rely on human clinical data to assess how well the virus will work in the long term,” she added.
In this early-stage study, scientists monitored the effects of an injection injected directly into the tumor in 39 patients.
In addition to destroying cancer cells, genes have been inserted into the virus used in the treatment so that it produces molecules called GM-CSF (similar to T-Vec), as well as GALV-GP-R, which have been shown to have antitumor properties. properties and a molecule similar to an anti-CTLA-4 antibody, which helps to “slow down” the immune system.
The results showed that of the nine patients who received the viral injection alone, one experienced his tumor completely disappear and remained cancer-free 15 months later. Two other patients with esophageal cancer and uveal melanoma experienced shrinkage of their tumors. Eighteen and 15 months later, respectively, their cancers had not progressed.
Another 30 patients received the injection along with the cancer immunotherapy drug nivolumab, which works by activating immune cells that attack cancer cells.
Of these patients, seven saw their cancer growth stop or slow, and six of these patients experienced no cancer progression 14 months after treatment.
All of the patients who participated in the trial had very advanced cancers that had no longer responded to other treatments or were ineligible for existing treatments. The biopsies showed more immune cells around the tumors and increased expression of genes that could help kill cancer cells.
The team hopes to identify patients in whom the therapy should be tested in phase II trials, said study leader Professor Kevin Harrington, professor of biological cancer therapies at the Institute of Cancer Research London and an oncologist. Consultant at The Royal Marsden NHS Foundation Trust.
Prof. Harrington told Medical News Today in an interview that the herpes virus really offered the “full package” as a candidate for genetic modification to create such treatments.
“There is no doubt that, in my opinion, the virus strain that has the strongest credentials for use in epithelial tumors is the herpes virus platform. The virus infects epithelial tissues extremely effectively, it is easily genetically manipulated. It has a relatively large capacity to carry genes that you want to put into the virus, so it’s a good vector vehicle for those genes,” he said.
He explained that there were also approved drugs available that could treat a herpes infection if the virus ended up replicating in places where it shouldn’t, although that hadn’t happened in tests.
“Many of the other viral platforms are limited in the range of cells they infect, have relatively small gene packaging capabilities and, in fact, are not genetically manipulable at all, with simple means,” he added.
Dr. McFaddent said that one limitation of using herpes viruses as the basis for these treatments was that they had to be injected directly into the tumor, while it was hoped that treatments based on smallpox viruses could be administered intravenously. .
“No one really knows at this point, what is the ideal platform for intratumoral injection or intravenous injection? So this will only be determined by future clinical trials. And like I said, the current data is a step in the right direction,” he added.
Source: news.google.com