美国国家公共电台 NPR After A Big Failure, Scientists And Patients Hunt For A New Type Of Alzheimer's Drug（在线收听）

After A Big Failure, Scientists And Patients Hunt For A New Type Of Alzheimer's Drug

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Scientists are changing course in their quest to treat Alzheimer's disease. The new direction comes after a series of failures with drugs aimed at a toxic protein called amyloid-beta. Now researchers are pinning their hopes on drugs that have other targets, and as NPR's Jon Hamilton reports, so are patients.

JON HAMILTON, BYLINE: Phil Gutis was 54 when he was diagnosed with Alzheimer's; that was three years ago.

PHIL GUTIS: I'm just being erased - all these memories, you know, the memory of my dog.

HAMILTON: His dog Abe, a Jack Russell who died last year. A few weeks ago, Gutis found himself leafing through pictures of Abe and trying to remember the dog who'd shared his life for 12 years.

GUTIS: But there were no memories. There were no memories of me and him. And then I told a friend about this, and she said, you don't remember walking on the trail and how he used to scamper ahead and try to trip you and da-da-da (ph)? And I'm like, no, I don't.

HAMILTON: Until recently, Gutis thought he might be able to preserve at least some of his remaining memories. He'd been part of a trial of an experimental drug called aducanumab.

GUTIS: Participating in this trial, it gave me hope for the future.

HAMILTON: There'd been a lot of excitement about the drug because it was really good at removing amyloid-beta from the brain. But in March, researchers announced that it didn't prevent dementia. Gutis says the news was a huge disappointment for both patients and researchers.

GUTIS: I think the scientists have largely said, OK, we give up, because this is - I mean, many drugs targeting this have now failed.

HAMILTON: So scientists are trying to figure out what comes next. They're looking at a range of strategies, from modulating the brain's immune system to protecting healthy brain cells. Dr. Daniel Alkon is president and chief scientific officer of a company called Neurotrope. He says the scientific community learned something important from all those failures with amyloid drugs.

DANIEL ALKON: Dealing with the amyloid is probably important, but it's not going to be sufficient.

HAMILTON: Alkon had suspected that for years. He'd spent decades as a researcher who studied memory and the wiring that allows brain cells to communicate. And that led him to focus on a feature of Alzheimer's that didn't involve amyloid.

ALKON: One of the earliest events in Alzheimer's disease is the loss of that wiring. And as the wiring loss progresses, the cognitive function loss progresses.

HAMILTON: So Alkon and a team of researchers studied mice that had been genetically altered to develop a condition similar to Alzheimer's. And he says they realized something surprising.

ALKON: You saw this very significant loss of wiring, and you could actually reverse it; you could regenerate the wiring.

HAMILTON: By creating new connections between brain cells. This process was controlled by a protein called PKC-epsilon. Alkon says the team thought, if they could find a way to tweak PKC-epsilon, maybe they could get the brain to replace some of the wiring lost in Alzheimer's.

ALKON: We asked, is there any drug, known drug, in the world that can target PKC-epsilon safely, without hurting a patient?

HAMILTON: And they found one - It's called bryostatin-1, and it comes from a marine animal often mistaken for seaweed. Decades ago, researchers at the National Cancer Institute studied bryostatin-1 as a treatment for cancer; that effort didn't work out. But Alkon thought the drug might work for Alzheimer's because it had a dramatic effect on PKC-epsilon. So his team tried it, first on animals and then a small group of people, including a man named Frank.

ALKON: He had been sitting in a chair, staring at the ceiling, hallucinating. Within a couple of weeks of our treating him, he started swimming, playing pool, communicating, feeding himself.

HAMILTON: Two preliminary studies hinted that patients with advanced Alzheimer's could get better with bryostatin-1, and a more rigorous study of about 150 people suggested a modest benefit. So now Neurotrope is working to confirm those results. And of course, bryostatin-1 is just one potential Treatment. Several others target a toxic substance called tau that builds up inside the brain cells of Alzheimer's patients. And Dr. Steven Arnold of Harvard Medical School says, still, other drugs target inflammation or the way that brain cells clear out toxins.

STEVEN ARNOLD: These are all really powerful ways in which we can perhaps prevent, delay or even reverse Alzheimer's disease.

HAMILTON: Arnold says there's growing interest in drugs that can protect brain cells and help them function better.

ARNOLD: If we do that, we may find that it's not only good for Alzheimer's disease, but it's also good for other degenerative conditions of the brain, like Parkinson's disease.

HAMILTON: In the meantime, Alzheimer's patients like Phil Gutis continue to look for anything that might help. Gutis says he was devastated when the drug trial he'd been in was halted, but he says he'd welcome the chance to try again.

GUTIS: I mean, it's probably going to be at least a year before I'm eligible to be in another medical trial. But I would - in a second.

HAMILTON: Jon Hamilton, NPR News.