More Alzheimer’s drugs head for FDA review: what scientists are watching


A clinical-trial participant receives an infusion of Biogen’s aducanumab in May 2021.Credit: Kayana Szymczak/New York Times/Redux/eyevine

When the US Food and Drug Administration (FDA) accredited biotechnology agency Biogen’s drug for Alzheimer’s illness in June, regulators hoped to usher in a brand new period of therapy for the neurodegenerative situation. But the choice adopted an unbiased advisory committee’s near-unanimous vote to reject the drug, referred to as aducanumab — and as an alternative divided the neighborhood. Some researchers assume that the approval will bolster the event of drugs for treating mind illness, however others see it as a blemish on the FDA’s integrity and an impediment to progress.

Pharmaceutical firm Eli Lilly in Indianapolis hopes that its antibody donanemab, which works in an analogous strategy to aducanumab, could have a greater reception. The agency plans to complete submitting its drug candidate for FDA approval within the subsequent few months, paving the best way for a call within the second half of 2022. Meanwhile, Biogen, based mostly in Cambridge, Massachusetts, and its accomplice Eisai, based mostly in Tokyo, are racing to finish the submission of information for one other competitor, lecanemab. The regulatory destiny of those therapeutic hopefuls might foretell the way forward for Alzheimer’s and form neurodegenerative drug growth programmes for years.

Following the Clinical Trials on Alzheimer’s Disease (CTAD) convention final week in Boston, the place researchers mentioned the drug candidates, Nature opinions the questions everyone seems to be asking.

Do amyloid-lowering drugs assist sufferers?

According to the ‘amyloid hypothesis’ of Alzheimer’s illness, the build-up of a protein referred to as amyloid-β within the mind causes neurodegeneration. Aducanumab and its would-be opponents clear clumps of amyloid-β from the mind. But medical trials haven’t meaningfully demonstrated that these therapeutics sluggish reminiscence loss or cognitive decline. This is a selected level of rivalry for aducanumab, an antibody drug that’s now in the marketplace for round US$56,000 per yr, regardless of prematurely halted part III trials and the messy knowledge set that was submitted for approval.

Some hope that Lilly’s donanemab trials will finally present proof of profit. The first of those is an 18-month part II trial referred to as Trailblazer-Alz that enrolled 257 individuals. It confirmed1 that the cognitive capabilities of people that acquired the antibody declined extra slowly than these of placebo recipients. The common distinction was 3.20 factors on a 144-point scale.

For Mark Mintun, senior vice-president of neuroscience analysis and growth at Lilly, this sign is promising. Treated sufferers averted round six months of cognitive decline over the course of the examine, he says. With longer use of donanemab, members would possibly profit much more, he speculates.

Rob Howard, a psychiatrist at University College London, is unconvinced, nevertheless. The noticed 3.20-point distinction is “trivial”, he says. Best-case interpretations of aducanumab and lecanemab knowledge level to equally marginal results. Generic donepezil — a 25-year-old Alzheimer’s drug that treats the signs somewhat than the foundation reason behind the illness — outperforms the antibodies, he provides.

Sharon Sha, a neurologist who oversees neuroscience medical trials at Stanford University in California, says extra knowledge are wanted to evaluate the medical utility of those drugs. “We really need to make sure that [these antibodies] are changing the daily lives of patients or keeping them stable,” says Sha, an investigator in trials of all three therapies.

When will strong knowledge be obtainable on whether or not these therapies enhance cognition?

One of the circumstances that got here with the FDA’s approval of aducanumab was that Biogen run a ‘confirmatory trial’ making certain that the antibody really helps individuals. The biotech agency has but to launch that trial, and the FDA gave it 9 years to gather the outcomes — a protracted timeline that has contributed to the uproar over the drug’s approval.

For Ezekiel Emanuel, a bioethicist on the University of Pennsylvania in Philadelphia, the information want to return sooner. The accelerated approval pathway ought to be up to date to mandate quicker assortment of high-quality confirmatory knowledge, he wrote in the Journal of the American Medical Association2.

Assuming that the FDA approves donanemab utilizing the identical accelerated approval pathway, Lilly, too, must affirm the advantage of its antibody. The pharma agency is working a 1,500-patient part III trial referred to as Trailblazer-Alz2 of donanemab for individuals in early phases of Alzheimer’s. Results are due within the first half of 2023 — after the antibody’s potential approval — and would possibly present the information wanted. Another part III trial is recruiting 3,300 sufferers prone to Alzheimer’s, to check whether or not earlier use of the antibody delays the onset of dementia. This trial will run till 2027.

The outcomes of those research would possibly assist to heal a divided subject. “Could [the approval of aducanumab] have been done better? I think everyone agrees that this could have unfolded more effectively,” Mintun says. “But as the data accumulate, people will get more and more convinced, and the divisions, I think, will disappear.”

Will the FDA approve the anti-amyloid antibodies?

The accelerated approval of aducanumab established a precedent for others to comply with. The FDA can approve Alzheimer’s drugs on the idea of their potential to take away amyloid-β from the mind — with out clear proof of cognitive profit. Pharma watchers due to this fact assume that an accelerated approval for donanemab is probably going, barring undisclosed points relating to efficacy, security or manufacturing.

“Of course they’ll approve it,” Howard says. “It’s difficult to see how they can have approved aducanumab and not approve donanemab.”

Donanemab’s amyloid-lowering potential is just not in dispute. In Trailblazer-Alz, it lowered amyloid-β ranges on common by virtually 80%. These knowledge recommend that it outperforms aducanumab on amyloid clearance. Lilly has setup a head-to-head trial of donanemab and aducanumab to straight examine their amyloid-lowering capabilities.

Will the FDA reconvene its outdoors specialists for upcoming approvals?

A flashpoint within the approval of aducanumab was the FDA’s choice to ignore its advisory committee’s issues in regards to the antibody.

The company convened this panel of specialists one yr in the past to debate Biogen’s sophisticated knowledge set. In 2019, the corporate halted growth of aducanumab after interim analyses of two part III trials confirmed that the antibody was not serving to individuals. Months later, it reversed course and mentioned it will search approval on the idea of a contemporary evaluation of the information that hinted at cognitive profit.

One panellist mentioned that Biogen’s statistical interpretation of its knowledge was akin to “firing a shotgun at a barn and then painting a target around the bullet holes”. Ten panellists voted in opposition to approval, and one abstained.

After the FDA accredited aducanumab, three members of this committee give up in protest.

High-ranking FDA officers defended their place in distinguished journals3,4 and newspapers, however the fallout has continued. Off-the-books conferences between the FDA and Biogen might need enabled the approval, STAT News reported in June. The federal watchdog on the Department of Health and Human Services is now reviewing the steps that led as much as the approval, and is because of launch a report in 2023. Two congressional committees within the US House of Representatives are additionally investigating the choice.

If confirmed by the US Senate, Robert Califf, US President Joe Biden’s latest choose to head up the FDA, must deal with any repercussions of this choice — and determine transfer ahead with accelerated approvals. But with the regulatory precedent established, there is no such thing as a clear requirement for an unbiased advisory committee to evaluation donanemab.

For Caleb Alexander, an internist and epidemiologist on the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, the necessity is as an alternative reputational. “The FDA’s credibility has unfortunately taken a significant hit with the management of aducanumab,” says Alexander, a member of the committee that suggested the FDA to not approve the drug. “If they want to salvage their credibility, they need to be sure that this new product is reviewed by an advisory committee.”

Will the FDA restrict who will be handled with these therapies?

The FDA initially accredited aducanumab for anybody with Alzheimer’s — a illness that impacts greater than six million individuals within the United States. But Biogen examined the antibody solely in a subset of those sufferers.

After the backlash, the company narrowed the specification to individuals with “mild cognitive impairment or mild dementia stage”, to higher match the group examined in Biogen’s trials. But the drug’s label, which specifies who ought to use it, doesn’t stipulate that folks should have proof of amyloid build-up of their mind — a key requirement for inclusion in Alzheimer’s trials.

One concern is that the FDA’s pointers put individuals prone to doubtlessly deadly unintended effects, for little or no probability of profit. Aducanumab may cause mind swelling. Most sufferers don’t expertise any signs from this swelling, however they want common mind scans — which are onerous and costly — to keep away from doable problems.

Lilly examined donanemab, which additionally causes mind swelling, in individuals at early phases of the illness. It measured amyloid-β, in addition to ranges of one other protein marker of illness, referred to as tau, to restrict trial enrolment to the sufferers who are almost certainly to learn. Mintun declined to touch upon Lilly’s imaginative and prescient for therapy eligibility. “This is a conversation I would love to have with the FDA,” he says.

Howard expects one other broad approval from the FDA. “It doesn’t make any sense to punish Lilly and treat them differently from Biogen,” he says. The onus then falls on docs to work out how and when to make use of the antibody safely.

But Emanuel argues that the FDA ought to slender eligibility for all anti-amyloid therapies — and be sure that real-world utilization of any drugs accredited below accelerated approval are carefully aligned with clinical-trial designs. “If a court develops a bad precedent, you don’t continue the bad precedent. You revise the precedent,” he says.