A widely used blood pressure medication may be the key to preventing brain function loss common after radiation treatment, and could offer an improved quality of life for cancer patients, according to a study published in this month's International Journal of Radiation Oncology, Biology, Physics.
Researchers at Wake Forest University Baptist Medical Center in Winston-Salem, N.C., using a rat model, drew on a hypothesis from previous studies that a compound similar to the anti-hypertensive drug losartan (Cozaar, Merck) can prevent the cognition loss that has been closely associated with radiation therapy for brain tumor treatment.
Investigators said their findings appear to validate the hypothesis in rats, and are optimistic that the same theory could be applied in a human clinical trial setting because the drug used has a long-established safety profile in patients who have taken it to treat high blood pressure.
"We need to kill cancer cells but also prevent or reduce treatment-related side effects," said Mike E. Robbins, PhD, a professor in the department of radiation oncology at the Brain Tumor Center of Excellence at Wake Forest. "One very interesting feature of this compound is that it has never shown any pro-tumor effects. If anything, it appears to have anti-tumor properties. We're very close to having a compound that will protect the normal brain from cognitive injury as a result of radiation and, at the same time, we may very well increase the likelihood of curing brain cancer patients of their tumors."
The study involved three groups of 80 rats, and each group was divided in half to either receive radiation or no treatment, according to the authors. Then, each of those halves was divided into two more groups: one that received L-158,809, the compound similar to losartan, in its drinking water, and one group that received plain drinking water. The rats that received the drug received it before, during and for different time intervals-14, 28 or 54-post-radiation. In addition, a small group of rats continued to receive the drug for only five weeks after radiation.
Researchers found that administering L-158,809 before, during and for as little as five weeks after radiation either prevents or lessens the severity of radiation-induced cognitive impairment.
"The extent of cognitive impairment experienced by patients who undergo radiation therapy varies in terms of how it is recognized," Robbins said. "Sometimes the patient realizes that their short-term memory is fading or that they've lost the ability to multi-task...They just can't keep thoughts in their brain. Sometimes it's a friend or partner that realizes the impairment, but once it is noticed, it is not going to improve. Cognitive decline resulting from radiation is not stable. It is a chronic, progressive condition."
An estimated 170,000 patients undergo radiation therapy annually to treat primary or metastatic brain tumors. At least 50 percent of adult patients who undergo the treatment and live six months or more post-therapy experience some level of cognitive decline.
In children, the effect is even greater, Robbins said. "All will have some form of cognitive impairment if they are long-term survivors and, thankfully, with today's technology, most children will survive long-term," he noted.