Bipartisan senators are calling for a hearing into how the Medicare program could, or even should, cover an expensive new Alzheimer's drug with questionable benefit.

Sens. Elizabeth Warren (D-Mass.) and Bill Cassidy (R-La.) want the Senate Finance Committee to examine the challenges facing Medicare that were brought about by the Food and Drug Administration's (FDA) decision to approve Biogen's Aduhelm.

"Notably, FDA approval does not guarantee Medicare coverage, and so the program will need to answer an enormous question: should it cover a new and expensive Alzheimer’s medication, and if so, how?" the senators wrote in a letter to committee Chairman Ron Wyden (D-Ore.) and the ranking member Sen. Mike Crapo (R-Idaho).

Aduhelm was the first new Alzheimer's drug approved in nearly 20 years, but the approval came over the near-unanimous objections of the FDA's expert advisory committee. 

Aduhelm is not a cure for Alzheimer's, and the FDA made its decision without clear evidence that the drug can even slow the progression of the disease.

Medicare’s long-standing practice is to make coverage determinations without taking cost into consideration. But Biogen put the list price of the drug at $56,000 a year per patient, and the potential patient population exceeds 6 million people.

The Senate Finance Committee has jurisdiction over Medicare, and covering Aduhelm could cost the Medicare program billions of dollars.

Biogen has said that some 1.5 million Americans with early-stage Alzheimer's will be eligible for the drug.

But under the broad label that FDA approved, the drug is available to all Alzheimer’s patients, even though Biogen only tested the drug in people in the earliest stages of the disease. The FDA also did not place any limits on treatment duration, suggesting that patients could remain on the drug indefinitely.

Since Alzheimer's disease primarily impacts seniors who are eligible for Medicare, taxpayers will largely foot the bill for the new drug.

An analysis from the nonpartisan Kaiser Family Foundation found Aduhelm could cost seniors on Medicare more than $11,000 in annual copays.

If just 500,000 beneficiaries are prescribed Aduhelm, it would cost the program nearly $29 billion a year, more than any other medication. Medicare spending for all prescription drugs combined was $37 billion in 2019.

"This level of potential new spending, particularly for just one product with limited evidence of clinical efficacy thus far, tests the program’s resiliency,” the senators wrote.