What’s next for Biogen’s newly approved Alzheimer’s drug?

Dr. William Burke goes over a PET brain scan at Banner Alzheimer's Institute in Phoenix.Matt York/Associated Press

The US Food and Drug Administration on Monday approved Cambridge-based Biogen’s experimental therapy for Alzheimer’s disease.

Here’s what you need to know about this historic decision and what happens next.

What is the significance of the decision?

The FDA announced its approval of Biogen’s controversial Alzheimer’s drug, aducanumab, which will be marketed under the brand name Aduhelm, for use in the United States. The decision makes Biogen the first company to bring a new Alzheimer’s drug to market since 2003. Alzheimer’s is the sixth leading cause of death in the United States and affects an estimated 5.8 million Americans, according to the Centers for Disease Control and Prevention.

What will happen next?

The FDA approved Aduhelm under what it calls the “Accelerated Approval” pathway, which allows it to clear drugs that are likely to result in a benefit for patients, but where there still remains some uncertainty. As part of the approval, the agency asked Biogen to conduct a larger clinical trial to show that the drug’s goal — removing a sticky plaque that builds up inside the brain of Alzheimer’s patients — results in benefits to patients.

How would the new therapy work?

The drug aims to slow cognitive decline in people with early symptoms of the disease. Biogen and Eisai, a Japanese drug firm that collaborated on the drug, designed the therapy to attack beta amyloid, a plaque that builds up inside the brain, which some scientists believe contributes to memory loss and functional decline associated with the disease. Aducanumab is a monoclonal antibody made from the immune cells of older people with no (or uncommonly slow) cognitive decline.

Who is eligible for the drug?

Aduhelm is approved for patients with Alzheimer’s disease.

The medication is designed to treat patients in the earlier stages of the disease who have mild cognitive decline — a population estimated at about 2 million people in the United States — but the FDA did not limit the drug’s use to a certain subset of patients.

How will patients take the medication?

Aduhelm is administered intravenously by infusion for about one hour every four weeks. Patients must obtain a recent brain MRI before starting the treatment, according to the drug’s prescribing information. Additional MRI scans will be required before a patient’s seventh and twelfth infusion to monitor possible side effects.

Study participant Henry Magendantz received an infusion of Biogen's experimental Alzheimer's drug at Butler Hospital in Providence on May 27.Kayana Szymczak/NYT

What is the screening process?

A 2017 analysis by researchers at the nonprofit Rand Corp., sponsored by Biogen, predicted that by 2019, 88 million Americans would be eligible for cognitive impairment screening, with 15 million screening positive. Cognitive impairment is a possible early sign of Alzheimer’s disease.

Biogen said that starting in September, it would partner with CVS Health on an initiative to make cognitive screenings available in underinsured and diverse communities in several cities, including Atlanta, Boston, Miami, and Philadelphia. Through the program, patients or their caregivers would be able to consult with health care providers about their results.

How much will the drug cost?

Biogen said the “yearly cost at the maintenance dose” is $56,000. That sum is a “list price” based on the average weight of a patient and does not represent the amount that will be paid by patients with insurance. Out-of-pocket costs for insured patients will vary depending on an individual’s coverage, the company said.

When will it be available?

In the company’s first-quarter earnings call in late April, CEO Michel Vounatsos said Biogen has been working for months to evaluate sites across the United States where the treatment could be administered to patients. He said he expected “more than 600 of these sites will be ready to treat patients shortly after a potential approval.”

“Our team is currently working to evaluate the capacity at these and other sites to absorb an influx of Alzheimer’s patients,” Vounatsos said in April.

A spokesperson for Biogen said the company plans to begin shipping the drug in about two weeks.

How is it different from other Alzheimer’s drugs?

Aduhelm is designed to target the underlying process of Alzheimer’s disease, while other medicines on the market only treat its symptoms. Other Alzheimer’s drugs, such as Namenda and Aricept, come in pill form, but Biogen’s treatment would be administered through intravenous infusion.

Why is the medicine controversial?

Last November, a federal advisory panel concluded that Biogen failed to prove its experimental medicine for Alzheimer’s disease was effective, with outside experts going as far as to say the company was cherry-picking positive trial data and discarding negative results. Then in May, a drug-pricing watchdog released a similar opinion about aducanumab, calling Biogen’s efficacy data “insufficient” to warrant an annual price tag above $8,300, far less than the $50,000 that some analysts had predicted, if the drug were approved.

The intense debate over whether Biogen’s drug works, and what data the firm used to make that claim, has left some medical experts deeply skeptical. “If it gets the green light, I can’t see myself recommending it to my patients,” wrote Jason Karlawish, a professor at the University of Pennsylvania’s Perelman School of Medicine in an article in STAT. “Biogen hasn’t made a convincing case for it.”

What is the drug’s back story?

Biogen first started working with the aducanumab drug compound in 2007 after partnering with Swiss drugmaker Neurimmune. Biogen pushed the drug through early development and began to enroll patients in two late-stage clinical trials to test its efficacy in 2015, following promising early data.

However, in March 2019, Biogen and Eisai announced they would discontinue both studies after an independent monitoring panel found the drug would not likely help patients. The news sent Biogen stock into a freefall, wiping out $18 billion of the company’s value in one day. But just seven months later, Biogen made a stunning announcement: It was resurrecting the drug after an analysis of additional data suggested aducanumab might work after all. Since then, the company had been eyeing approval from the FDA.