Brain and nervous system tumors are some of cancer’s most lethal forms; someone diagnosed with this type of cancer has a roughly one in three chance of surviving the next five years. Certain immunotherapies that stimulate the immune system to target specific cancer markers have shown progress against several brain cancers, but in many cases (and even more frequently in the most severe forms of brain cancer, like glioblastoma), the presence of tumor-infiltrating neutrophils is the key factor that has prevented these therapies from working.

Neutrophils are a type of white blood cell that the immune system uses to attack cancer in its early stages. However, scientists have discovered that, if a tumor survives the body’s initial defenses and continues to grow, these tumor-associated neutrophils actually start to work for the tumor rather than against it by suppressing further anti-cancer interventions from the immune system.