A new study from Washington University School of Medicine in St. Louis suggests a simple blood test — administered before CAR-T cell treatment is initiated — may identify which patients are predisposed to developing neurotoxic side effects after CAR-T cell therapy. Severe side effects can include seizures, brain swelling and strokes. Evidence of a stroke (red arrows) is seen on this MRI scan of the brain of a patient who developed neurotoxic side effects after CAR-T cell therapy.