(Reuters) - Gradually increasing the dose of Biogen Inc's experimental Alzheimer's disease drug appeared to reduce the risk of brain swelling compared to higher fixed doses, interim 12-month results from a small study released on Thursday showed.
The closely watched drug, aducanumab, led to significant reductions in amyloid plaques in the brain compared with a placebo among the 31 early-stage Alzheimer's patients given titrated, or gradually increased dosing, according to data from the Phase I study.
"These data appear solid to us, and if anything provide additional confidence in the program and viability of the titration regimen," Evercore ISI analyst John Scotti said in a research note late on Thursday.
Any successful Alzheimer's drug is expected to reap multibillion-dollar annual sales.
In the group of trial patients given titrated dosing, 35 percent experienced a side effect involving a fluid shift in the brain, compared with 55 percent given a high fixed dose, Biogen said.
Biogen last year began enrollment in two Phase III trials of aducanumab using titrated dosing, but those results are still several years away, said Samantha Budd Haeberlein, the company's vice president, clinical development.
The amyloid reduction and slowing of mental decline seen in patients in the titration portion of the Phase I study after 12 months of treatment were similar to what was reported earlier this year for patients who received fixed doses of aducanumab.
Full details of the study were being presented at an Alzheimer's meeting in San Diego on Friday.
Patients in the study had either mild or prodromal, meaning early pre-symptomatic, Alzheimer's disease, researchers said.
Aducanumab works by removing brain plaques largely made from a protein called beta amyloid. Other companies have also tried to develop drugs that block beta amyloid, but all failed to significantly slow cognitive declines, and some were also associated with brain swelling.
The most spectacular recent failure was Eli Lilly and Co's experimental solanezumab, designed to soak up beta amyloid from the bloodstream.
Lilly last month said its infused drug failed to slow mental decline, compared with placebo, among patients with mild Alzheimer's. That largely dashed hopes for the drug and cast further doubt on whether beta amyloid is the right target for attacking the memory-robbing disease that affects millions of people.
Some Alzheimer's experts have suggested the approach might work very early in the course of the disease. They said once brain plaques can be observed it may already be too late for the drugs to provide significant benefit.
Biogen shares rose 1.45 percent to close at $289.54.
Reporting by Bill Berkrot, Ransdell Pierson and Deena Beasley; Editing by David Gregorio and Will Dunham