Drug May Reduce Cognitive Decline Following Radiation for Brain MetastasesA drug already approved to help improve cognition in some patients with dementia may limit declines in memory and cognitive function in patients who are undergoing whole-brain radiation therapy (WBRT) to treat cancer that has spread to the brain. Results from a clinical trial to test the drug, memantine (Namenda), in patients with brain metastases were presented October 28 at the American Society for Radiation Oncology (ASTRO) annual meeting .
More than 60 percent of patients with brain metastases who undergo WBRT experience problems with cognitive function within 4 months after completing treatment, explained the trial’s lead investigator, Dr. Nadia Laack of the Mayo Clinic Cancer Center, during a press briefing. The intent of the NCI-supported trial was to determine whether memantine could prevent memory decline in patients, rather than to test whether the drug improved progression-free or overall survival, Dr. Laack noted.
The phase III randomized trial, conducted by the Radiation Therapy Oncology Group and dubbed RTOG-0614, enrolled more than 550 patients, who received either memantine or a placebo during WBRT and for 6 months afterward. The researchers assessed participants’ memory and other cognitive functions, such as the ability to process information and make decisions, before and after treatment. Many patients in the trial died or had cancer that continued to progress, however, so after 24 weeks only 149 patients could be evaluated.
Patients whose disease progressed “often refused testing so, in effect, we were largely evaluating patients who had not progressed,” Dr. Laack explained in an e-mail message.
In patients treated with memantine, memory decline took longer to appear and was less severe, although the improvement was not statistically significant. However, the risk of cognitive decline fell 17 percent, a drop that was statistically significant.
“Although memantine was discontinued at 6 months, the effect on cognitive function was maintained for the duration of the trial, suggesting that memantine may be preventing radiation injury rather than simply treating cognitive dysfunction,” Dr. Laack said.
Based on the trial’s results, memantine will likely now be used as standard therapy for patients undergoing WBRT to treat brain metastases, she added. “We do feel that this is going to impact practice tomorrow and that, for future trials, memantine will be the standard against which other agents are tested.”
This study was funded in part by the National Institutes of Health (CA21661, CA32115 and CA37422, RTOG U10 CA21661, and CCOP U10 CA37422).