The blood-brain barrier keeps foreign substances from entering the brain. That’s good when it comes to toxins and germs, but it makes treating tumors in the brain trickier. By shielding the brain from things that would harm it, the blood-brain barrier also blocks the chemotherapy that would help it.

William Walker—a researcher with the West Virginia University School of Medicine—is investigating whether the blood-brain barrier is more likely to admit chemotherapy drugs at different times of day. 

His study—funded by the National Institutes of Health—shows that the blood-brain barrier is dynamic rather than static and suggests that properly timed chemotherapy treatments could better reach the tumors they’re targeting. 

Dark-phase chemotherapy treatments

The researchers found that the chemotherapy they administered during the dark phase killed more brain tumor cells than the ones given in the light phase.

Dark-phase chemotherapy treatments also did a better job of delaying neur ...