Academic and industry experts said on Tuesday they have convinced U.S. regulators to ease safety restrictions imposed on clinical trials of Alzheimer's drugs, a move that could improve the chances that a drug being developed jointly by Pfizer and Johnson & Johnson might succeed.
A 2008 study of 240 patients testing that drug, known as bapineuzumab, found a dozen cases of a brain swelling condition called vasogenic edema, shaking confidence in the safety of agents that reduce levels of a protein called beta amyloid that accumulates in the brains of Alzheimer's patients.
That study prompted the U.S. Food and Drug Administration to issue stricter safety guidelines for clinical trials of drugs that alter amyloid in the brain, Maria Carrillo of the Alzheimer's Association said in a telephone interview.
The guidelines restricted patients in the trials to having no more than two incidents of cerebral microhemmorhages, or tiny leaks of blood in the brain, before they enter a study. They also called for frequent MRI scans to check for brain swelling or other problems that might be caused by the study drugs, Carrillo said.
Under new guidelines ironed out through the Alzheimer's Association's Research Roundtable — which included both industry and academic researchers — the FDA has now eased those guidelines, Carrillo said in a telephone interview.
Many companies, including Pfizer and J&J and Eli Lilly, are working to develop drugs that reduce levels of this protein.
Carrillo said the new guidelines — based on the latest research — recognize that many patients with Alzheimer's disease have had these types of brain events, and excluding so many people from clinical trials would make it more difficult to find effective drugs.
"We were able to bring together all of the literature involved in the discussion of MRI abnormalities that could occur when you are aging with Alzheimer's disease and when you are participating in clinical trials with an amyloid-modifying agent."
Carrillo said the group of industry experts and researchers submitted their report to the FDA, which has adopted the new recommendations. The report was published on Tuesday in the journal Alzheimer's and Dementia.
The new guidelines allow some patients who develop brain swelling to stay in clinical trials, she said.
"We don't want to compromise safety, but we also want to make sure as many people as possible can participate in Alzheimer's clinical trials," Carrillo said.
In January, Eli Lilly said one patient in ongoing trials of the company's drug solanezumab temporarily developed brain swelling, although it was not clear whether the patient was taking the Lilly drug or a placebo. The problem was not seen in a follow-up brain scan and the patient resumed treatment.
Rachel Schindler, an Alzheimer's disease expert at Pfizer who worked on the study and wrote an editorial in the journal, said, "broadening the restrictions would allow a better understanding of the potential risks and benefits of amyloid-lowering treatment."
In May, J&J said it plans to seek U.S. regulatory approval for bapineuzumab in 2012 or 2013, but analysts have said more studies may be needed because of issues with brain swelling.
Currently, there are no drugs that alter the course of Alzheimer's, which affects 26 million people globally and costs more than $600 billion a year to treat.