A Biogen Idec Inc. drug that targets plaque buildup in the brain slowed cognitive decline in patients with early and mild forms of Alzheimer’s disease in a small, early-stage study, lifting the company’s stock to all-time highs and adding to the debate on how to treat the debilitating disease.
The treatment still requires larger and longer drug trials, and may not be suitable for all patients. However, the results excited observers because of the consistency of the drug’s effects, which increased with higher doses. Analysts also were encouraged by brain imaging scans showing plaque reductions that corresponded to clinical improvements.
“While still very early, these data are more impressive than anything we’ve seen in [Alzheimer’s disease], justifying the pre-data excitement,” Christopher Raymond, a Robert W. Baird analyst, said in a research note.
Shares of Biogen rose 9.8% to $475.98 through the close of regular trading on Friday, adding nearly $10 billion to the company’s total value. Earlier in the day, shares hit $480.18, the highest price ever for the stock, which had a closing price of $433.65 on Thursday.
Biogen, primarily known for its stable of multiple sclerosis therapies, had sales of $9.7 billion last year.
Biogen said in December that the drug, called aducanumab, had produced a statistically significant effect on cognition. But the company hadn’t yet released detailed results, which were highly anticipated by those looking to handicap the odds of success in larger studies needed for U.S. Food and Drug Administration approval.
Biogen is planning to begin a late-stage study later this year of aducanumab that will include more than 1,000 patients, Chief Medical Officer Alfred Sandrock said in an interview on Friday. Biogen’s drug, also known as “BIIB037,” is designed to help clear the brain of beta amyloid plaques, which many scientists say play a role in causing Alzheimer’s, a progressive, memory-destroying condition associated with older age.
But the so-called “amyloid hypothesis” is controversial, and other drugs targeted at amyloid plaques have failed in late-stage studies.
Biogen’s data Friday was from an early-stage trial that tracked most patients over 54 weeks and used two cognitive tests to measure aducanumab’s clinical effect on patients.
The study was designed to evaluate aducanumab’s safety, which Biogen said was “acceptable.” Patients taking the drug did experience fluid buildup around their blood vessels, a potentially serious complication, and 22% of patients experienced headaches, compared with 5% of patients receiving placebos.
The drug’s effects on cognitive function were included as “exploratory” study endpoints, the company said.
Using the Mini Mental State Examination, or MMSE, patients receiving the largest dose of aducanumab worsened on average by 0.58 points, or 2.56 points fewer than the 3.14-point decline among placebo patients, a statistically significant advantage, the company said. Baird’s Mr. Raymond had said that a difference greater than one to two points between aducanumab and the placebo would be “meaningful.”
In a separate measure, called the Clinical Dementia Rating sum of boxes, or CDR-SB, patients on the highest dose of Biogen’s drug declined by 0.59 points, or 1.45 points fewer than patients on placebo, who declined by 2.04 points.
“The reduction in the level of cognitive decline was higher than we had expected,” Bernstein analyst Geoffrey Porges said. “In short, the more drug [that] patients took, the less their cognition declined, and the longer they took it, the bigger the difference between treated and control patients,”
Data from the study, which included 166 patients with minimal to mild Alzheimer’s symptoms, was presented Friday at a medical meeting in France. Patients were randomly assigned to receive placebo or varying doses of aducanumab.
“We’re very excited by the findings,” Biogen’s Dr. Sandrock said. “We think it could result in a very important disease-modifying therapy for patients.”
The most serious adverse event associated with aducanumab was the presence of the fluids surrounding patients’ blood vessels in imaging scans, also known as amyloid-related imaging abnormalities, or ARIA, the company said. The abnormalities, which were generally observed early on in treatment, were more common in patients with an Alzheimer’s-related gene called ApoE4.
According to the National Institute on Aging, ApoE4 is present in up to 15% of the population and in about 40% of all people with late-onset Alzheimer’s.
“The drug still appears to have a relatively narrow therapeutic window,” Bernstein’s Mr. Porges said.
Biogen’s inclusion of patients with early or minimal symptoms, sometimes called prodromal Alzheimer’s, makes it difficult to interpret the study data because the rate of cognitive decline in patients with minimal symptoms would be less than in patients with mild forms of the disease, Allen Roses, professor of neurology at Duke University School of Medicine, said in an interview. Dr. Roses is also chief executive of a biotechnology company developing a genetic biomarker in conjunction with an experimental Alzheimer’s drug being developed by Takeda Pharmaceutical Co.
Biogen didn’t break down the study results by patients’ disease severity, but a spokeswoman said the groups “were balanced” between study arms. The company’s planned late-stage study will be needed to fully understand the drug’s effect, she said.
The Cambridge, Mass., company is in search of new products to drive sales growth following the successful 2013 launch of its multiple-sclerosis therapy Tecfidera, which had global sales of $2.9 billion last year. Another of Biogen’s promising early-stage drugs, anti-Lingo-1, is currently being tested in a mid-stage study of multiple-sclerosis patients.
Alzheimer’s drug development has suffered a series of setbacks in recent years when drugs that looked promising in early-stage studies flopped in larger clinical trials. The large potential market for Alzheimer’s treatments, in tandem with the biotechnology industry’s successes in bringing new drugs to market for other diseases in recent years, has created excitement around Biogen’s drug.
Investors are “forgetting about the high risk” associated with Alzheimer’s drug development and “focusing on the high reward,” said Ravi Mehrotra, a Credit Suisse analyst.
By
Joseph Walker
Write to Joseph Walker at joseph.walker@wsj.com