CHEMOTHERAPY’S EFFECTIVENESS MAY VARY WITH TIME OF DAY
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 neurological symptoms, like strange walking patterns and loss of muscle control.
They also increased the median survival rate by about 20%.
The findings appeared in "Frontiers in Oncology"
In all our projects, we try to ask, ‘If we see an effect molecularly, does that translate? Is there a functional relevance to it? To an extent, it might be pointless if we increase the amount of chemotherapy within the brain tumor at a certain time, but we don’t see any functional difference, we don’t improve survival, or we don’t improve changes in neurological deficit. So, these results were great to see"q commented William Walker.
Questions remain. Does the human blood-brain barrier fluctuate, too? If it does, is it more receptive to chemotherapy in the day or at night? Do the fluctuations reflect the fact that humans are diurnal creatures (more active during the day), or are they an effect of light exposure itself?