George Gates, who is in a clinical trial for the Alzheimer's...

George Gates, who is in a clinical trial for the Alzheimer's drug donanemab, at his home in Smithtown on Friday. Credit: Howard Schnapp

Families of people with Alzheimer’s disease reacted with frustration, and experts with surprise, to the announcement Friday that the Food and Drug Administration would delay a decision about a promising new drug, donanemab, to allow for further study.

“I don’t understand what more they can want,” said Maria Gates, of Smithtown, whose husband, George Gates, participated in a clinical trial for the drug after he was diagnosed with Alzheimer’s five years ago. For people with Alzheimer’s, “There is nothing else to do … you can take the drug or slowly go away, until there’s nothing left.” 

Gates said that her husband, 62, a former software developer who once surfed year-round, seemed to age into an 80-year-old man after his diagnosis. But he began improving last fall, a change she attributed to the drug. “I’m hoping that this year he gets in the water again.”

Drugmaker Eli Lilly said in a release that “the FDA has informed Lilly it wants to further understand topics related to evaluating the safety and efficacy of donanemab.” The drug can, in some cases, lead to life — threatening bleeding or fluid accumulation in the brain, Lilly said.

Lilly had expected the FDA to decide on donanemab’s approval by the end of the month, but the agency’s decision to convene an advisory committee to discuss the trial will likely push any action into April or later, according to the release.

The FDA’s decision “is very surprising to me and to a lot of experts in the field,” said Dr. Nikhil Palekar, director of the Stony Brook Center of Excellence for Alzheimer's disease and of the medical center’s Alzheimer’s disease Clinical Trials Program. “We thought this medicine would be approved.”

Palekar said it was “one of the first medicines that has finally shown some modest effects in slowing the progression of the disease.”

Alzheimer’s affects millions of Americans, including about 60,000 Long Islanders. It is progressive and fatal, characterized by buildup in the brain of amyloid and tau proteins that degrades thought, memory and language.

Donanemab is part of a class of drugs called amyloid antibodies, developed over the last decade, that were the first to slow cognitive decline in patients with Alzheimer's. Other drugs in the class include lecanemab, priced at $26,500 after it was approved last year, and aducanumab, which was approved in 2021 even though critics questioned its efficacy. The drug’s manufacturer said in January it would be discontinued.

The drugs do not cure Alzheimer’s or reverse its effects, but donanemab “significantly slowed clinical progression” of the disease for some patients with early symptomatic Alzheimer's disease at 76 weeks, according to a July, 2023 Journal of the American Medical Association article on trial results.

Regulators appear to have questions about how donanemab would be prescribed and how long it should be used, Palekar said. These stem from Lilly’s study, which discontinued use of the drug for patients after scans showed the plaque had cleared. That raises the question, Palekar said: “Do patients need to be on this medicine even after amyloid plaques have cleared?”

Regulators will also seek more information about how tau accumulation impacts the medication’s effectiveness, Palekar said. Lilly’s trial grouped participants into groups with high and medium accumulation and found greater effect for those with medium accumulation. Trials for other amyloid antibodies were conducted differently, making comparison difficult, Palekar said.

Northwell Health’s Dr. Marc Gordon, chief of neurology at Zucker Hillside Hospital, said regulators appear to “feel the data may be somewhat more complicated and need a closer look,” particularly after their experience with aducanumab.

The new drug could offer doctors an effective, if modestly powerful tool, he said, with at least one practical advantages over lecanemab: while both drugs are delivered by infusion, a costly, hourlong process, it would require that process every four weeks, instead of every two.

In an email Friday Lori Maldavir, Director of Program Outreach for Alzheimer's Association Long Island Chapter, said the FDA decision illustrated “a balance of safety and wanting people to have access to effective treatments. We respect the due diligence while at the same time wanting decisions to be made expeditiously as people are suffering.”

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