In a surprising move, the acting commissioner of the Food and Drug Administration has requested an investigation of the FDA itself, specifically its contacts with Biogen regarding a controversial new Alzheimer’s drug.

In June, the FDA took the rare step of approving the drug Aduhelm, overruling an advisory committee that had urged denial because of doubts about its efficacy. The agency ruled that evidence showing this monoclonal antibody reduces toxic amyloid clumps in the brain met the regulatory threshold for “accelerated approval.” Advocates urged approval in the absence of any drugs offering hope for Alzheimer’s patients.