Empa May 28 2026 When a tumor manages to nestle itself in the brain of a living being, it has - from the tumor's perspective - done something particularly clever. It has hidden itself behind one of the most powerful barriers with which the body protects its most important organs: the blood-brain barrier, a highly selective filter that only allows certain substances to pass through. Most drugs are not among them, though. It is therefore a major challenge for biomedical research to find an