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It looks like Biogen may be on the right track with its Alzheimer’s drug

Inside a lab at Biogen in Cambridge.Suzanne Kreiter/Globe file photo

The approach to fighting Alzheimer’s disease that targets the buildup of plaque in the brain got a boost Friday when Biogen Inc. released fresh study data on its experimental drug to treat the neurodegenerative disorder.

The Cambridge biotech’s findings confirmed data published last year from an early-stage clinical study. Among other things, they showed the drug continued to reduce amyloid plaque in patients who kept taking it after the initial round of testing. The additional data should “bolster investor confidence in the ongoing investment Biogen is making in this program,” Leerink Partners biotech analyst Geoffrey Porges wrote in an investors note.

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But even with this sign of progress, Porges’s optimism was tempered — he estimated the chances of Biogen’s drug making it to market at just 35 percent.

The failure of another Alzheimer’s drug to help patients, disclosed last month by Eli Lilly & Co., lowered the expectations of analysts for a near-term treatment of the memory-wasting disease, which afflicts more than 5 million Americans and about 47 million people worldwide. Lilly’s drug also sought to remove amyloid plaque, but in a different way than what Biogen is trying with its medicine, called aducanumab.

Lilly released more detailed info on its unsuccessful trial Thursday, making it clear that the company’s experimental drug didn’t clear up amyloid plaque on patients’ brains. That was encouraging news for Biogen’s program — and the patients and families following it — because it left open the possibility that other methods for removing plaque could still work. If Lilly’s drug had reduced plaque and still not helped patients, it would have raised deep questions about Biogen’s efforts.

“Amyloid not over after all,” Porges wrote, summarizing Wall Street’s hope that Biogen remains on the right track.

Shares of the Cambridge-based company edged down $1.79 to $287.75 on Friday, a loss of less than 1 percent. The stock gained 1.5 percent Thursday after a medical conference in California prematurely released a summary of Biogen’s latest findings.

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Biogen shares were trading up early on Friday, but investors pulled back in the afternoon, apparently because the company’s presentations showed that a patient taking aducanumab in the clinical trial suffered a seizure. While the patient lived, the episode underscored safety concerns.

Overall, however, the clinical findings provided grounds for optimism. Biogen reported that more than 100 patients with early indications and mild cases of Alzheimer’s who kept taking aducanumab in the early-stage trial continued to show a slower rate of cognition declines and a reduction in Alzheimer’s-related amyloid plaque.

The data also showed that step-by-step dosing increases given to a new set of about two dozen patients in the same study significantly reduced the percentage of those who suffered from swelling in the brain compared with patients given only the highest dose in an earlier part of the study. Both sets of patients have a gene putting them at risk for the disease.

Aducanumab also significantly reduced amyloid plaque in the new set of patients, compared with a smaller group of new patients who were given a placebo.

“This is promising,” Biogen vice president of clinical development Samantha Budd Haeberlein said. “It supports the data we’ve already seen from aducanumab. It shows that we can take patients more slowly to their designated doses and still see efficacy. And it supports the approach we’re taking in our [late-stage] trial.”

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Biogen is currently enrolling patients in that trial, which will eventually involve up to 3,000 people in more than 20 countries. The outcome will be pivotal to the company’s chances of getting aducanumab approved by the Food and Drug Administration and other regulators. But it is likely to be at least a year before it reports its first data.


Robert Weisman can be reached at robert.weisman@globe.com. Follow him on Twitter @GlobeRobW.