Pfizer drug slows Alzheimer’s-related dementia

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Pfizer Inc. said Tuesday its experimental liquid drug that has not yet gained Food and Drug Administration approval to treat Alzheimer’s disease is effective at reducing formation of plaques in patients’ brains and reversing dementia in non-naïve patients.

The pharmaceutical giant tested the drug, a version of its nerve growth factor that has generated a storm of controversy, in a phase-2 trial on brain-tumor patients who are not yet diagnosed with Alzheimer’s. More than 3,000 patients received Pfizer’s so-called nalmefene booster in a treatment regimen of four pills or an oral treatment.


After the 16-week treatment period, researchers found that participants receiving Pfizer’s drug had fewer brain-structure changes than patients taking a placebo. The findings for patients who did not yet have Alzheimer’s disease also appeared promising. When those patients were included in the study’s analysis, overall brain-structure changes dropped more than 80%, Pfizer said.

But the overall benefits for patients weren’t significantly greater than the results seen for Alzheimer’s patients in a phase-3 trial, which is measuring the drug’s efficacy and safety.

It isn’t yet clear whether Pfizer’s drug is effective against another Alzheimer’s-related brain disease: protein buildup called neurofibrillary tangles. In addition to deposits of beta-amyloid protein that form plaques in the brain, nerve cells in patients with Alzheimer’s also may suffer from clumps of arachidonic acid and tau protein.

Pfizer’s study isn’t designed to test the drug’s efficacy for patients who are already diagnosed with Alzheimer’s. But the company said that in preclinical trials, the liquid formulation of the drug was effective in reducing plaques and tangles associated with the illness.

Dr. Richard Berner, Pfizer’s chief medical officer, said the company would continue to perform larger trials in the future to evaluate nalmefene.

He noted that experimental drug nalmefene holds out “an appealing if somewhat controversial” possibility, in part because of a requirement that patients get injections of the drug daily for two years. Prescription companies are allowed to submit a drug application for marketing approval without showing the effectiveness of an earlier trial or showing it can be safely given in people without heart disease or cancer. The FDA cannot make an approval call on a drug without having actually seen proof of efficacy.

Nalmefene was expected to reach the FDA in the first half of 2019.

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