New Alzheimer's Drug May Be Safer Than Thought
Drug-Related Brain Swelling May Resolve Over Time, Research Suggests
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Brain Swelling Often Symptomless
In one study, researchers reviewed more than 2,500 MRI brain scans from 262 patients who had participated in bapineuzumab studies and identified 15 cases of brain swelling that had been missed the first time around. But none caused any symptoms, says Reisa Sperling, MD, director of clinical research of the memory-disorders unit at Brigham and Women's Hospital in Boston.
The researchers also confirmed the 21 cases of brain swelling detected in earlier studies. Eight of these patients experienced symptoms, including headache and confusion, she tells WebMD.
The study also showed that people with the ApoE4 gene variant that has been linked to an increased risk of Alzheimer's and those who took higher doses of bapineuzumab appeared to be at increased risk for brain swelling.
Patients taking the highest dose in the early studies were switched to a lower dose after the first reports of brain swelling emerged.
Swelling Wanes Over Time
In the other study, Salloway and colleagues examined scans from 194 patients for signs of brain swelling.
The risk of brain swelling dropped from 7% after the first three doses to 3% for the fourth through 10th doses, he tells WebMD.
The patients took bapineuzumab, which is given by infusion every 13 weeks, for an average of about two-and-one-half years.
Brain swelling was the most common side effect of treatment, occurring in 9% of patients. Overall, about one in four participants experienced some effect that was thought to be related to bapineuzumab; 85% of them were mild to moderate.
Salloway says no conclusions about the drug's effectiveness can be drawn from these studies. Effectiveness data, from the phase III studies, should become available next year.
Ironically, brain swelling appears to be a sign the drug is doing what it is supposed to do in the early stages of treatment, Salloway says.
"Bapineuzumab mobilizes amyloid from the brain and it goes to the blood vessels. In people with a lot of amyloid, it might [clog] the blood vessels early on, causing some leakage of fluid [that can lead to edema]. Then, as the drug clears more amyloid away, there is not much leakage," he says.