By Bill Berkrot
March 20 (Reuters) - An experimental drug from Biogen Idec became the first Alzheimer's treatment to significantly slow cognitive decline and reduce what is believed to be brain-destroying plaque in patients with early and mild forms of the disease, according to a small study likely to reignite hopes of a treatment.
Alzheimer's is expected to strike as many as 75 million people worldwide by 2030 without effective treatments, likely costing billions of dollars year in care. A successful treatment would pay some of the richest rewards in medicine.
Biogen is entering a field littered with expensive failures from such players as Pfizer Inc and Eli Lilly and Co.
The 166-patient trial of the Biogen drug, aducanumab, tested four groups who each received a different dose against a fifth group who received a placebo.
The treatment led to reductions in brain amyloid, a type of plaque believed to play a key role in the development of Alzheimer's symptoms, according to interim data presented at a medical meeting in Nice, France, on Friday. The plaque reduction was more pronounced as the dose of the drug increased and over time.
It marks the first time an experimental drug demonstrated both a statistically significant reduction in amyloid plaque and a slowing of clinical impairment in patients with mild disease, said Alfred Sandrock, Biogen's chief medical officer.
"It's a bigger treatment effect than we had hoped for," Sandrock said.
Biogen will begin enrolling patients later this year for a large Phase III trial that could be used to seek approval of its drug.
Biogen said it increased its chances of success by carefully screening patients to exclude those with other forms of dementia misdiagnosed as Alzheimer's, and by testing only those early in the disease.
"We imaged every patient coming into study, so we knew that every patient had Alzheimer's disease and plaque," Biogen Chief Executive George Scangos said in an interview. "It's hard to think of a reason why these data are not representative of the actual activity of the drug."
HIGHER DOSES SHOW GREATER EFFECT
Safety and tolerability was considered acceptable, the company said. There was a big jump in the incidence of amyloid-related imaging abnormalities-edema (ARIA-E), or water surrounding brain tissue, at the two higher doses among patients with a gene associated with the highest risk for developing Alzheimer's. These highest-risk patients also dropped out of the trial at a higher rate. Most of the ARIA-E was asymptomatic or mild and resolved over time, Sandrock said.