(HealthDay News) — Medicare announced Thursday that it will limit its coverage of the pricey new drug Aduhelm to patients with Alzheimer disease enrolled in clinical trials of the drug.

Approved amid controversy last year by the U.S. Food and Drug Administration, the latest decision was meant to protect patients while gathering more clinical data on whether the medication actually helps slow declines in thinking, according to officials with the U.S. Centers for Medicare & Medicaid Services (CMS).

“There is the potential for promise with this treatment; however, there is not currently enough evidence demonstrating improved health outcomes to say that it is reasonable and necessary for people with Medicare, which is a key consideration for CMS when making national coverage determinations,” Lee Fleisher, M.D., CMS chief medical officer and director of the Center for Clinical Standards and Quality, said in an agency news release. “In arriving at this final decision, we looked at the very unique circumstances around this class of treatments and made a decision that weighed the potential for patient benefit against the significance of serious unknown factors that could lead to harm.”

While considering its final decision, CMS received 10,000 comments on its website, a mix of emotional pleas from patients, families and groups representing Alzheimer’s patients, as well as doctors and experts who urged caution because the drug has serious potential safety risks and its effectiveness is still uncertain. CMS Administrator Chiquita Brooks-LaSure told The New York Times that “the vast majority” of comments were for “really limiting coverage of Aduhelm to a really controlled space where we could continue to evaluate its appropriateness for the Medicare population.”

Among the concerns about Aduhelm are that while in one clinical trial patients showed a slight slowing of thinking declines, an almost identical trial showed no benefit at all. Side effects were serious for about 40% of patients, who experienced brain swelling or brain bleeding that ranged from mild to serious.

Advocacy groups had campaigned for broader coverage of the drug, saying restricting it was discriminatory because not all Alzheimer’s patients have access to clinical trials.

“CMS has created unnecessary barriers for individuals with Alzheimer’s disease. Patients with Alzheimer’s, a fatal disease, should have FDA-approved treatments covered by Medicare just as those facing other diseases do,” Harry Johns, CEO of the Alzheimer’s Association, said in a statement released Thursday. “Notably, CMS has said in its decision the only way for patients to access the first approved FDA treatment targeting amyloid in those living with Alzheimer’s is to enroll in a clinical trial. While we note CMS has expanded where those clinical trials may take place, in reality this remains an unnecessary and never before imposed barrier to access an FDA-approved treatment.”

The New York Times Article