Plaque-Pillaging Alzheimer’s Drug Advances Toward Promising Phase III Trial

Actor Gene Wilder’s death earlier this week brought silent sufferers of Alzheimer’s disease into the limelight. Behind many a beloved face is also the onslaught of vanishing memories.

But a phase II trial of a new drug called aducanumab—developed by Biogen—is bringing some hope to the legions of people who deal with this oppressive disease. In its highest dose, the drug was recently shown to annihilate amyloid plaques in the brains of a subset of the study’s 165 participants.

It could cost up to $2.5 billion dollars to test it widely, but the investment might be worth the price tag: if it works, aducanumab could treat people for Alzheimer’s before they even show symptoms. Even if the disease isn’t eliminated completely, delaying its progression by five years could cut the number of people who live long enough to see its effects in half. Instead, those people would likely die from other causes before Alzheimer’s has a chance to take hold.

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The shadow of Alzheimer's disease affects how people experience aging—but that might change.

The drug is expected to help patients the most when it’s administered at the earliest stage of the disease. For that reason, it could prove a long-standing theory. Here’s Antonio Regalado, reporting for Tech Review:

If the Biogen drug works, it will also basically prove the “amyloid hypothesis,” the dominant theory that Alzheimer’s is caused by the buildup of a peptide called amyloid beta as plaques on brain tissue. The drug sticks directly to the plaques and probably recruits scavenger cells called microglia to arrive and remove them.

“What they showed very nicely was a reduction in plaques as they increased the dose. This is the most significant part of the study, and it looks very convincing,” says Steven Paul, who is CEO of Voyager Therapeutics, a gene-therapy company, and previously co-invented a different anti-Alzheimer’s antibody currently being tested by Eli Lilly. Paul says Biogen’s drug is the first to break up plaques in this way.

The researchers’ next step is to embark on two larger phase III trials involving 2,700 volunteers worldwide. This phase will determine whether or not the drug not only clears plaques but also prevents memory loss and death. The downside is that some of the patients in the phase II study had to drop out due to side effects like brain swelling.

If the range of side effects were known and kept in check, though, this drug has the potential to save the U.S. up to $1 trillion over the next 30-something years. That’s a substantial payoff—and since phase II already hints at a positive outcome for phase III, most scientists are excited to surge ahead.

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