Three members of an independent panel that advised the U.S. Food and Drug Administration (FDA) on nervous system drugs had turned in their resignation after the agency approved medication for Alzheimer's disease.

Reuters reported that the resignation of the three members served as a protest against the agency's decision to approve Biogen's Alzheimer's disease product Aduhelm (aducanumab) despite the committee's recommendation not to approve the medication.

The FDA granted accelerated approval of the Alzheimer's drug based on the medicine's effect on a surrogate endpoint that is likely to predict a clinical benefit to patients, with a required post-approval trial to verify that it provides the expected clinical benefit.

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FDA Advisory Panel Members Resigns Over the Approval of Alzheimer's Drug From Biogen

Professor Aaron Kesselheim of Harvard Medical School, Dr. Joel Perlmutter of Washington University, and Dr. David Knopman of Mayo Clinic were the three members of the FDA's advisory committee who resigned this week.

"This might be the worst approval decision that the FDA has made that I can remember," said Dr. Kesselheim as reported by The New York Times

Kesselheim argued that the approval of the Alzheimer's drug was wrong because "there is no good evidence that the drug works."

The 11-member committee report found that the Alzheimer's drug did not show evidence that it has the ability to slow down cognitive decline in people who are experiencing the early stages of the disease. 

Furthermore, the advisory panel also discovered that the drug might cause serious side effects such as brain swelling and brain bleeding.

"My rationale was that the FDA needs to re-evaluate how it solicits and uses the advisory committees," said Kesselheim, who served on FDA's advisory panel on nervous system drugs since 2015. 

Kesselheim added that the panel's recommendations were not integrated into the FDA's decision-making in approving the Alzheimer's drug.

Meanwhile, Perlmutter argued that the drug's approval would endanger "future research into new treatments that may be effective." 

Perlmutter further noted that the therapy using the Alzheimer's drug aducanumab would cost billions. Perlmutter said the money could be better spent in developing better evidence for the medication or other "therapeutic interventions."

FDA on the Claims of the Advisory Panel Members

Despite the claims and opposition of the panel members to the approval of the Alzheimer's drug, FDA did not issue an official statement regarding the matter. 

Shannon Hatch, a spokeswoman for FDA, told The New York Times that the agency does not comment on matters related to individual members of the advisory panel.

Biogen, the Alzheimer's disease drug aducanumab developer, plans to begin shipping the drug in two weeks in more than 900 sites across the country. FDA noted that the drug is the first new treatment for Alzheimer's since 2003.

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WATCH: Evidence to Approve Biogen's Alzheimer's Drug Was Not 'Sufficient': Penn's Dr. Jason Karlawi - From CNBC Television