In a cancer research lab. (Drawing). – SEBASTIEN ORTOLA
- In recent years, oncologists have been treating patients with advanced cancer with immunotherapy.
- However, this treatment does not work for all patients.
- The absence of a molecule, CD 226, would be an explanation for this resistance to immunotherapy.
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It is an innovative treatment method for cancers, which in recent years has been used to treat those at an advanced stage.
Immunotherapy, which stimulates the patient’s immune system to defend itself – when chemotherapy attacks tumor cells – in 25% of cases where it was adopted, it offered a “lasting response”. This rate was only 11% when using other treatments.
Something to give serious hope. But it doesn’t work on everyone. An international team of researchers, headed by Toulousains, put his finger on a molecule that could well explain this resistance to this treatment. Or rather the absence of that called CD226, would be one of the keys to understanding resistance to immunotherapy.
[Publication CRCT] Cancer: a key mechanism of resistance to immunotherapy identified @crctoncopole @UT3PaulSabatier @IUCTOncopoleICR @FondationARC @INCa_veillePro @ToulouseCancer #Cancer https://t.co/W39FsKcGvF
– CRCT-Oncopole (@crctoncopole) December 7, 2020
This molecule is naturally expressed on T lymphocytes (like Killers) which have the function of defending the organism. Scientists had already demonstrated its important role for natural killer cells, lymphocytes of the innate immune system capable of killing tumor cells and infected cells.
Bad diagnosis in case of absence
“I continued to be interested in it and found that it disappeared on the surface of these natural killer cells in mice. In humans, it was absent from killer lymphocytes. In a context, the cell no longer expresses it ”, explains the doctor. Ludovic Martinet from the Toulouse Cancer Research Center, to the CD226 research department, the results of which have just been published in the
revue Immunity.
However, this molecule allows killer lymphocytes to recognize cancer cells. In their absence, they were no longer able to react. Looking at the diagnoses of 177 cancer patients, the researchers realized that this absence was mainly the signal of a bad diagnosis for patients with cancer, whether breast, lung or melanoma. .
And if this molecule is deactivated, it is then a self-defense mechanism of the T lymphocyte which is stimulated, and therefore in overactivation. “He tries to protect himself because overactivation is his death, this can lead for example to cytokine shocks, so he must manage to regulate himself. The CD226 molecule is not completely lost, but we must understand how to reactivate it and identify the mechanisms that allow it, ”continues Ludovic Martinet. Without this triggering other effects, because for the team of researchers, it is above all a question of keeping the benefit-risk for the patients.
In the longer term, knowing whether the molecule is present or not, and thus determining upstream whether the immunotherapy will be effective, is a real plus for orienting the treatment and carrying out an à la carte therapy. “Research is progressing, treatments too, but we have to give people real hope. Immunotherapy is one of them, it has made it possible to treat people who were convicted five years ago, ”concludes Ludovic Martinet.
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