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The use of genetically engineered viruses as an anti-cancer weapon, an approach that is attracting more and more attention in recent years, has yielded promising preliminary results for a type of tumor that typically affects the retina of young children.
animal tests and two 2-year-old girls no longer responding to any other treatment, the viruses were able to destroy at least part of the tumor and prevent metastasis, that is, the progression of cancer to other organs [19659002] The approach needs further refinement with more clinical trials (in humans). But this represents a hope because in many cases the only retinoblastoma treatment option, as this type of tumor is known, is the removal of the affected eye. In some cases, both eyeballs are compromised and must be removed.
It is estimated that 8,000 new cases of retinoblastoma occur each year. Among tumors diagnosed in children up to the age of one year, the disease accounts for 11% of cancer cases.
Unlike other cancers, the changes in DNA that trigger retinoblastoma are well known and affect the RB1 gene. The gene is not by chance a tumor suppressor, that is, it contains the recipe for the production of a molecule that helps control the proliferation of cells and prevents them from losing control. which usually triggers the formation of the tumor). 19659002] It is precisely by taking into account the key role of the RB1 gene that those responsible for the new weapon against retinoblastoma developed their work. The team, coordinated by Ángel Montero Carcaboso, from the Sant Joan de Deu Research Institute in Barcelona, worked with an oncolytic adenovirus, that is, a virus ready to cause lysis (rupture) of (19659002 The oncolytic virus has been modified so that it can only be propagated in cells whose copies of the RB1 gene no longer function (in the case of those belonging to retinoblastoma). ). In addition, the receptor, or chemical latch, used by the parasite to enter cells, is usually present only on the surface of tumors. To further strengthen the antitumor action, the virus has received instructions in its genetic material that allow it to destroy the matrix of molecules existing between the cancer cells, thus facilitating their spread.
Similar approaches have been tested in different types of cancer since the last decade. In the United States, in 2015, the FDA approved the commercial use of the first oncolytic virus, a modified version of the cause of herpes used to treat melanoma.
In addition to the direct action of the virus against the tumor. This approach is considered interesting because it can stimulate the attacks of the body's defense system against the disease if the viral particles carry genes that stimulate it. The safety against a generalized infection is guaranteed, in theory, by the fact that the virus preferentially invades the cancerous cells and by the local administration of the treatment, by means of injections for example.
To reach the experimental treatment with the two girls, the researchers first exposed to the virus cell cultures developed in the laboratory from tumors of 12 patients, which proved that the parasite was able to do so. infect and kill the tumor cells.
Later, during experiments on mice and rabbits, scientists showed that the viruses remained essentially limited to the region where they were injected, without affecting other organs, and protected the eyes from the eyes. Animal for months, while it would be necessary to eliminate them. and avoid metastasis.
Both girls had retinoblastoma that was no longer responding to chemotherapy. With them, the results were more complicated. At first, viruses produced an inflammatory process that prevented researchers from continuing to visualize the evolution of the tumor, ultimately leading to surgical removal of the eye.
In the case of the second patient, the inflammation was controlled and controlled. Viral application destroyed some of the tumor cells. The removal of the affected eye was therefore avoided. Now, it will be necessary to refine the strategy and make new tests in search of a higher success rate.
The study is in the latest issue of the journal Science Translational Medicine
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