WASHINGTON (Reuters) — Three members of a panel of outside advisors to the U.S. Food and Drug Administration have resigned in protest at the agency’s decision to approve Biogen Inc’s Aduhelm for treatment of Alzheimer’s disease despite the committee’s recommendation against doing so.

Mayo Clinic neurologist Dr. David Knopman, a panel member who had been recused from the advisors’ November meeting to review the drug because he was an investigator in clinical trials of Biogen’s drug, said he resigned on Wednesday.

“I was very disappointed at how the advisory committee input was treated by the FDA,” Dr. Knopman told Reuters. “I don’t wish to be put in a position like this again.”

The 11-member committee voted nearly unanimously in November that Biogen’s drug should not be approved, citing inconclusive evidence that the drug was effective. Due to his recusal, Knopman did not participate in the vote.

The FDA on Monday gave the drug “accelerated approval,” based on evidence that it can reduce a likely contributor to Alzheimer’s, rather than proof of a clear benefit against the disease.

On Tuesday, a member of the advisory group who voted against the approval, Washington University neurologist Dr. Joel Perlmutter, resigned from the committee, citing the FDA’s approval of Aduhelm without further discussion with its advisors.

The FDA said it does not comment on matters related to individual members of advisory committees.