New Drug Shows Promise Slowing Alzheimer’s
A neurologist describes what could be big progress in the battle against the disease
(This article appeared previously on PBS NewsHour.)
HARI SREENIVASAN, PBS NEWSHOUR WEEKEND ANCHOR: Last week came word about what could be a big step forward in the battle against Alzheimer’s, a new drug that during tests sharply slowed the cognitive decline of people with the debilitating disease.
For more, we are joined now by Dr. Samuel Gandy.
He is a neurologist and associate director of the Alzheimer’s Disease Research Center at Mount Sinai Hospital here in New York City.
So, I guess, first, what is the drug? What does it do?
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DR. SAMUEL GANDY, MOUNT SINAI HOSPITAL: So, the drug is aimed at a material that builds up in the brain during Alzheimer’s disease.
It’s a normal protein, normal substance of the brain, which changes its shape and clumps.
And these class of diseases called amyloid disease, or amyloidosis, are notoriously difficult to treat and the idea that with this drug is to help the brain clear those clumps away.
HARI SREENIVASAN: OK.
DR. SAMUEL GANDY: Sort of harnesses the immune system to clear those clumps away.
HARI SREENIVASAN: And is this just targeted at Alzheimer’s or are there any forms of dementia that could also benefit from a drug like this?
DR. SAMUEL GANDY: In any disease, in any dementia in which this particular protein builds up, this medicine could be effective.
For example, not only just Alzheimer’s disease but what we call mixed dementias, in which Alzheimer’s and, say, dementia due to multiple strokes can coexist.
In that case, the component due to Alzheimer’s will still be responsive to this drug.
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HARI SREENIVASAN: So, given that there have been other attempts at this, how significant is this sort of advancement?
DR. SAMUEL GANDY: Well, this is the first drug of any class aimed at amyloid that has shown any convincing signal.
So, not only have there been antibody trials, but also there are small molecules, pills, that are being tested that are aimed at the enzymes that make amyloid, for example.
None of those have succeeded so far. So, in terms of what we call the amyloid hypothesis of Alzheimer’s, that amyloid is key to the cause of the disease, this is — this is really important in terms of focusing or sort of confirming that that is a valid target.
HARI SREENIVASAN: So, why is this particular drug or this particular type of therapy different?
DR. SAMUEL GANDY: This is a biological. It’s a protein, what’s called a monoclonal antibody, and it’s directed at — specifically at this molecule that builds up.
And we’ve rarely been successful in this sort of medication, in this sort of disease. There’s one example of another amyloid that’s treatable.
This is the second example where we seem to have a lead on a strategy that looks to be successful.
HARI SREENIVASAN: So, Biogen, the company that made, saw a huge bump in their stock.
Obviously, investors seem very confident. But this is far off from actually getting to market, right?
DR. SAMUEL GANDY: It is. This is — it’s a small trial.
If you divide it up between — there’s only about 150, 160 subjects total. They were in six different groups. So, in each group, there were only about two dozen patients.
So, the FDA usually requires at least two much larger trials, and so those would have to now be under at least typical policy those would be required before it would be approved.
Now, the FDA has given some signals they would like to fast track this sort of thing, so they could change those rules.
But one would guess, if they ran the two trials in parallel, perhaps it would be ready in three, four years. But it’s hard to imagine being any faster than that.
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HARI SREENIVASAN: And there’s always side effects to drugs. I mean, are there any known side effects so far?
DR. SAMUEL GANDY: There are. And this particular side effect is one that occurs with a number of these biologicals.
There are antibodies like this for cancer, for example. And this is a swelling of the brain, or at least a change in the water content of the brain.
It’s often those symptoms, and usually if you sort of decrease the dose of the drug or space out the administration, it will resolve spontaneously.
But it’s fairly important to be — to survey for it. It’s readily detectable on MRI, before there are any symptoms. So, I think it would be manageable.
HARI SREENIVASAN: So, this is a category of biological drugs that you’re talking about. But are there other drugs — I mean, Alzheimer’s is so enormous in this country and elsewhere, are there other drugs that are following this kind of lead or in the clinical trials process?
DR. SAMUEL GANDY: Well, in Alzheimer’s disease — yes, there are — this particular strategy has been attempted before and has failed.
There was a drug by Pfizer, a drug from Lilly, which is still being evaluated, but the Pfizer drug was abandoned.
And it’s not quite clear why the Biogen trial succeeded where these others have failed.
There are a couple of possibilities. The first is that these biologicals can be different. One antibody made by one company may be slightly different from another in ways we may never even know.
So, it’s possible that the Biogen antibody is just superior to the others.
It’s also possible the Biogen trial design was the secret because they screened for people who had — they used amyloid brain scans to select the subjects. So, they knew that the people going in had amyloid in their brain.
In previous trials, those folks with amyloid negative or with negative amyloid scans were included.
So if they were not responsive to the medication, they would have diluted out the effect. And so, it’s possible that if these other drugs are tested with the same design, they might prove successful.