The U.S. FDA revised the label of Biogen’s Aduhelm (ingredient: aducanumab), reducing the number of people eligible for the treatment.

On Thursday, the regulator added the information in the label that Aduhelm should be used for “patients with mild cognitive impairment or mild dementia stage of the disease.”

Previously, the FDA said Aduhelm was indicated for the treatment of Alzheimer’s disease (AD). The updates reflected that the therapy was used in patients with mild symptoms in clinical trials and aimed to limit the prescription of the drug.

“Treatment with Aduhelm should be initiated in patients with mild cognitive impairment or mild dementia stage of disease, the population in which treatment was initiated in clinical trials,” the FDA said in the Indications and Usage section of the treatment’s label. “There are no safety or effectiveness data on initiating treatment at earlier or later stages of the disease than were studied.”

The FDA revised the label at the request of Biogen, news reports said. After the FDA granted accelerated approval for Aduhelm on the condition that it proves clinical benefit in confirmatory clinical trials on June 7, numerous health experts and patient groups criticized the FDA for granting the nod for a drug with insufficient evidence of benefit.

The FDA went ahead with giving conditional approval even though its advisory group did not recommend it based on the treatment’s clinical trial data.

Critics had said the FDA set the indication for a treatment that showed effect through a surrogate indicator, beta-amyloid, for all AD patients regardless of the causative mechanism.

Although AD patients in the clinical trials of Aduhelm were in the early stage of the disease, the FDA had allowed it for all stages of AD, they had said.

On June 23, Biogen issued a statement explaining information on Aduhelm's treatment and confirmatory clinical trials, the impact on the target patient population and financial burden, and the company's position on patient access.

Reflecting the AD community's opinions, the company voluntarily requested the label update to the FDA.

Alfred Sandrock, head of research and development at Biogen, said, “Based on our ongoing conversations with prescribing physicians, FDA, and patient advocates, we submitted this label update to clarify further the patient population studied across the three Aduhelm clinical trials that supported approval.”

He added that the company would continue to listen to the AD patient community’s needs as clinical practice adapts to the first-in-class treatment option.