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Last Friday, the FDA approved Amyvid, a drug for Alzheimer’s diagnosis that was created and developed by Penn faculty Daniel Skovronsky and Hank Kung. It dyes brain deposits of amyloid plaque, which are correlated with Alzheimer’s disease.

However, the FDA has treaded cautiously, approving Amyvid only for limited uses. If brains scanned with Amyvid test negative, then the patient will be deemed Alzheimer-negative.

Cases where the Amyvid scans test positive will only signify the patient has significant levels of plaque, but will not confirm an Alzheimer’s Disease diagnosis.

Jason Karlawish, a Penn professor of medicine and a practicing physician, agreed. He said he would only use the tracer on people with at least several months of cognitive problems “who are having a hard time figuring out what they have,” instead of using it to directly diagnosis Alzheimer’s.

As for more ambitious uses of amyloid imaging like using it to identify early onset Alzheimer’s, Karlowish said he would wait for more evidence supporting the amyloid hypothesis, the theory that amyloid plaque causes Alzheimer’s disease. “We’ll know within the next two to five years whether or not the amyloid hypothesis of Alzheimer’s disease is a viable hypothesis,” he said.

But Penn research fellow Babak Saboury, a co-author of a critical editorial against Amyvid, worried FDA approval of the tracer would give unwarranted weight to the amyloid hypothesis. “FDA approval is the legitimization of something.” Once a drug has been approved, it is significantly harder for scientists to challenge the concepts behind it.

That’s why it took so long for the FDA to approve Amyvid, Kung explained. “They agonized over each word very, very carefully.”

Ethical implications

Marketing the tracer also raises a host of ethical issues.

For one, critics argue that the tracer could cause more harm than good right now.

Since there is no drug on the market that successfully removes amyloid plaque, Saboury said there should be no rush to market the tracer. How useful can it be for patients to know they are at risk when there is no cure or treatment?

It will also be tough for patients to learn they are at risk for Alzheimer’s, and doctors will have to take that into account when deciding whether to use Amyvid.

In an exceptional illustration of these concerns, a woman participating in a study in Germany committed suicide after learning she had tested positive for amyloid plaque. But for the most part, patients in test studies have been able to cope with the news.

Moreover, Karlawish said, several groups of doctors “are right now working on guidelines for the appropriate use of florbetapir.”

Putting the tracer on the market could also speed up development for anti-amyloid drugs. With the tracer more widely available, progress in eliminating amyloid plaque could now be monitored in a large number of patients.

What worries College junior Mateen Moghbel, the student who wrote the first draft of the Amyvid-criticizing editorial, is “we don’t have enough evidence [Amyvid] can be used to diagnose Alzheimer’s or to validate other drugs.” So far, the FDA has not approved the tracer for these uses.

But the approval may still have unintended consequences. As Professor of Radiology Abass Alavi explained, although the FDA approval only concerns negative diagnoses, physicians could “do whatever [they] want to” with Amyvid data.

He worries “a lot of people will get drugs that are harmful, which costs a lot of money that cannot be paid by the insurance companies.”

If the tracer is approved, families will be eager to use the tracer and even anti-amyloid drugs that might be available in the future. This is why, Moghbel said, “we want to have a solid foundation.” He says more research should be done before the tracer is marketed.

Yet research is driven by pharmaceutical companies, Kung remarked. Research is expensive, and “FDA requirement costs millions and millions of dollars.” Only commercial companies have the funds for efficient research that can push drugs to market and benefit patients.

This is why researching the amyloid hypothesis in labs is not viable, he said. “In an ideal situation, yeah, if someone gave me money to do research I would do it.” But companies need a financial incentive to pursue research: the possibility of creating something they can market.

The research will happen, but not in the way Moghbel and his colleagues envisioned it. Doctors and patients in “the market will decide whether [the tracer] is useful or not,” Kung said.

Avid, Skovronsky and Kung’s company, was the smallest company in the race to develop an amyloid tracer. Other versions are still being developed by Bayer Healthcare, GE Healthcare and AstraZeneca. Kung said this was a victory for Amyvid. “To be first on the market is always an advantage,” he said. This week, he celebrated and brought chocolates for everyone in the lab.

Amyvid will enter the market in June.

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