Perhaps you have already heard of immunotherapy, this treatment that has revolutionized cancer treatment for ten years? But did you understand what that meant? To sum up, immunotherapy is training your immune system to “turn” against the cancer. But how does it work exactly? A recent study published in the journal Cancer Cell, led by Inserm explains it to us concretely.
Normally, when a cancer cell threatens to grow, the immune system spots it and sends T cells (for “killers”) who will cling to it and destroy it. But this mechanism does not always work naturally, because some cancer cells express a marker on their surface – called PDL-1 – which has the ability to “paralyze” T lymphocytes. “These can attach to the cancer cell but not destroy it, as if they were caught in a straightjacket” explained to Top Santé the oncologist, Jérôme Fayette, on the occasion of a file on immunotherapy. “Immunotherapy is going to lift this paralysis, break the straitjacket, so that the immune system can do its job, remarked the specialist. Unlike chemotherapy, immunotherapy does not act directly on the cancer cell: it gives back its weapons to the immune system.
Open the door wide to let the killer lymphocytes through
Killer lymphocytes are white blood cells found naturally in the blood. Corn how do they reach tumours, what is their route? The better we understand where they go and how they act, the more we will be able to use them for more types of cancer, explains Inserm. “Scientists have discovered that HEV vessels – for High Endothelial Veinule – very special blood vessels, constitute the major entry point for lymphocytes into tumours. Using sophisticated microscopy techniques, the researchers were able to film the passage of lymphocytes from the blood to the tumor in animal models.”
It also made them realize thatincreasing the amount of these HEV blood vessels could make immunotherapy more powerful in destroying tumors. In short, this amounts to opening the door wider to allow more killer lymphocytes to pass through, an attack of greater magnitude in short. In patients with metastatic melanoma, the researchers found that the more HEV vessels there were, the better the patient responded to immunotherapy. The next step ? Develop treatments to increase the proportion of HEV vessels.
Source: Cancer treatment: identification of blood vessels that allow killer lymphocytes to access and destroy tumors, Inserm, January 3, 2022.
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