The Food and Drug Administration is more likely to grant a broader approval to a closely watched therapy for Alzheimer’s disease, now that it’s gotten renewed backing from a committee of experts who advise the agency on brain medicines.
During a meeting Friday, the experts voted 6-0 that recently collected clinical trial data confirm the therapy, known as Leqembi, indeed benefits Alzheimer’s patients. The FDA is weighing whether to expand a conditional approval given to Leqembi earlier this year into a full one, and the committee’s conclusion may nudge the agency to do so.
While the FDA isn’t required to follow the guidance of its advisers, it typically does. The agency should decide by July 6 whether to expand Leqembi’s label.
Such an outcome could substantially increase how many patients can get ahold of Leqembi and other, similar Alzheimer’s drugs. Currently, the government insurance program Medicare, which covers the majority of people eligible to receive these drugs, has a policy in place that strictly limits access. But the program has signaled it will relax its rules for reimbursement if Leqembi secures full approval.
Wall Street analysts believe Leqembi, with greater insurance coverage, will become a blockbuster product for its developers Eisai and Biogen. The team at the investment firm RBC Capital Markets, for instance, estimates the drug will eventually generate as high as $10 billion in annual sales.
Leqembi’s conditional approval hinged on an 850-person study that convinced FDA staff it was reasonably likely to provide some level of benefit to Alzheimer’s patients. To confirm those results, Eisai and Biogen ran a larger, almost 1,800-person trial, results from which became available last September.
That trial met its main goal, showing participants declined 27% more slowly when given Leqembi compared to a placebo, as measured by a scale that assesses mental and physical function. The trial also used other, well-known tests for Alzheimer’s patients, and found positive data supporting Leqembi’s effectiveness.
Since those results became available, Alzheimer’s doctors have debated the impact a treatment like Leqembi could have for patients. Some see the drug as an important victory in a research field marred by failure, while others believe it offers marginal benefits at best.
FDA staff appear to have a more positive view of the drug. Their assessments, according to Teresa Buracchio, acting director of the neuroscience office in the FDA’s Center for Drug Evaluation and Research, are “generally consistent with the results presented.” And the ways in which data from the larger study were collected and analyzed “capture the symptoms and impacts of Alzheimer’s disease that are meaningful to patients.”
“FDA is aware that there is much public discourse about the clinical meaningfulness of the change demonstrated with the lecanemab compared to placebo,” Buracchio said. “I would like to clearly state that the agency considers the results of [the study] to be clinically meaningful.”
Panelists agreed. “I thought the study clearly demonstrated clinical benefit,” said Robert Alexander, the meeting’s chair and chief scientific officer at the Banner Alzheimer’s Institute.
One-fifth of patients in the study treatment group experienced “ARIA,” a known side effect for Alzheimer’s drugs like Leqembi that can manifest as brain swelling or tiny brain bleeds. A smaller portion, 9%, of participants in the placebo group had ARIA.
Three people died in an extension portion of the study, during which all participants were able to receive Leqembi. Two of the patients had experienced brain bleeding, and in the third researchers noted a “possible cerebrovascular accident” and severe ARIA.
The FDA says it’s still unsure what role Leqembi played in the deaths, although agency reviewers did not rule out a link to the drug.
Safety was a focus during Friday’s meeting, as agency advisers sought clarity on whether Leqembi’s side effects might disproportionately affect certain groups, such as people who are on blood thinners or who have certain genes believed to put them at higher risk of developing both Alzheimer’s and ARIA.
The FDA itself has also questioned whether factors like concomitant medications or a condition common among Alzheimer’s patients, “cerebral amyloid angiopathy,” pose a safety risk for patients on Leqembi.
Yet, the FDA doesn’t seem poised to make major changes to Leqembi’s existing safety guidelines, which already warn about the need to monitor for ARIA, especially among those genetically predisposed to it.
When asked about cerebral amyloid angiopathy, for example, Buracchio said the agency currently deems it more of a theoretical risk.
“Contraindications are appropriate when the risk from the use of a drug clearly outweighs any therapeutic benefit, and should only be used for known risks,” she said. “So in this case, we think a warning is appropriate until we understand this a little bit better.”
Panelists agreed that cerebral amyloid angiopathy was worth monitoring, although they noted challenges in diagnosing it. At least one expert said he would not want to use Leqembi or another drug like it in patients with inflammation related to the condition.
To analysts, the meeting’s overall tone was supportive of Leqembi. Mizuho Securities’ Salim Syed called the experts’ clarifying questions “fairly benign,” while Michael Yee of Jefferies found there were “no major surprises.”
“Panelists aren't really nitpicking the data, and we see no real concerns on label restrictions,” Yee wrote in a note to clients Friday afternoon ahead of the committee’s formal vote.
Among six voting members, all concluded results from the larger study of Leqembi validated its use treating Alzheimer’s patients.
The meeting also included an open public hearing. Of 21 speakers, about two-thirds were in support of Leqembi’s full approval. Patients and their caregivers who testified said they feel like the drug has or will help stabilize the disease, and has become a valuable source of hope.
"I have to step back 10 years when I was the primary caregiver for my father. And even with the risks, and there are significant concerns there, I can't tell you what I would have paid to have this option,” said Colette Johnston, a voting member and the committee’s patient representative.
Editor’s note: This story has been updated with additional detail from the meeting.