Researchers at the Spanish National Cancer Research Centre (CNIO) propose a new treatment for brain metastases that respond poorly, or not at all, to immunotherapy , and provide a biomarker to predict in which cases it should be used. Our bodies have a mechanism to destroy anything that attacks it, be it viruses, bacteria or cancer cells: the immune system. Cancer grows when tumor cells fool this system into not attacking them.
Cancer immunotherapy uses drugs to prevent cancer cells from blocking the immune system, but immunotherapy doesn't always work. For brain metastasis -;when a tumor that started in another organ spreads to the brain-;immunotherapy has recently been tried, with mixed results. "Brain metastasis poses a serious clinical problem," explains Manuel Valiente, head of the CNIO Brain Metastasis Group and director of the study whose results are now being published.
"Patients with advanced brain metastases, that is, those who can already perceive symptoms of metastases, don't respond well to immunotherapy. But even patients who respond well to immunotherapy increasingly relapse, often because of new metastases in the brain." In other words, immunotherapy combined with blocking antibodies doesn't seem to be the optimal way to fight brain metastasis.
One possible reason is the presence of the blood-brain barrier, a kind of permeable membrane that filters blood entering the brain to protect it from toxins. But this vascular barrier also hinders the entry of antibodie.