In the face of criticism about Biogen’s recently greenlighted Alzheimer’s therapy and a call for a federal investigation into its approval, company executive Al Sandrock published an open letter last week (July 22) to correct “misinformation” about the drug and the regulatory process it underwent, STAT reports.

“It is normal for scientists and clinicians to discuss data from experiments and clinical trials, to debate, and to disagree, on the interpretation of data,” Sandrock wrote. “Recently, however, there has been a turn outside the boundaries of legitimate scientific deliberation.” The data on aducanumab are “complex,” and the drug’s path to market was not “conventional,” he notes. “But the road to innovation is rarely straightforward, and Aduhelm is not an exception.”

The US Food and Drug Administration (FDA) approved Biogen’s monoclonal antibody aducanumab (Aduhelm) on June 7 for early stage Alzheimer’s disease—the first new therapy approved for the neurogenerative disorder in nearly two decades. (A month later, it amended the approval to include only Alzheimer’s patients with mild cognitive problems.) The decision went against the recommendation of the FDA’s own advisory panel, however, and the following week three of them resigned in protest, The New York Times reported at the time.

Indeed, aducanumab’s approval has been highly controversial, with many scientists raising concerns about the drug’s efficacy. Earlier this month, the FDA called for a federal investigation of the approval process—an unusual move for the agency, The New York Times reported—amid questions about communications that may have happened between the agency and Biogen. For example, in early May 2019, Sandrock had an unofficial meeting with the head of the agency’s neuroscience division, after which time Biogen representatives worked closely with the agency to go through data from the company’s studies, STAT has reported.

“It’s really important that an investigation happen publicly and quickly so that we find answers to some of the many outstanding questions swirling around this decision,” Brigham and Women’s Hospital and Harvard Medical School’s Aaron Kesselheim, one of the advisory panel members who resigned, tells the Times.

“To the extent these concerns could undermine the public’s confidence in F.D.A.’s decision, I believe it is critical that the events at issue be reviewed by an independent body,” FDA acting commissioner Janet Woodcock wrote in an open letter to the Department of Health and Human Services’s independent Office of the Inspector General on July 9.

In response, Sandrock penned his own open letter. “We welcome a formal review into the interactions between the FDA and Biogen on the path to the approval of aducanumab,” he writes. “A better understanding of the facts is good for everyone involved to assure confidence in both the therapy and the process by which it was approved as we prioritize the issues that affect patients.”

For now, however, healthcare providers are grappling with whether to offer the $56,000/year drug, and to which patients. The Cleveland Clinic and the Mount Sinai Medical Center have said that they will not offer the therapy, STAT reports, although Biogen has noted that 900 sites are gearing up to do so.

“The letter is no substitute for a report of the trial data in the peer reviewed academic literature,” Samuel Gandy, a professor at Mount Sinai Hospital in New York, tells STAT. “Physicians are on their own to work out whether and if so how to use this drug. The label offers almost zero guidance. The least the company could do is publish the results of the trials so that all the stakeholders could see not only all the data but all the same data.”