Shares of Biogen BIIB sank to their lowest levels of the session, weighing on the broader biotech sector following reports that the head of the FDA has called for a wide-ranging federal probe into how the company's controversial Alzheimer's drug, STAT News reported.

In a letter published Friday, Acting Commissioner Janet Woodcock asked the independent Office of the Inspector General to investigate how staff from the agency interacted with Biogen in the run-up to the June 7 approval of Aduhelm. The complaint cited reporting that the agency worked uncomfortably closely with Biogen executives to get the drug to market. Most suspiciously, this included an off-the-books meeting and an unprecedented decision to approve Aduhelm through a regulatory shortcut.

"There continue to be concerns raised. . .regarding contacts between representatives from Biogen and FDA during the review process, including some that may have occurred outside of the formal correspondence process," Woodcock wrote in a letter to acting Inspector General Christi Grimm. To the extent these concerns could undermine the public’s confidence in FDA’s decision, I believe it is critical that the events at issue be reviewed by an independent body such as the Office of Inspector General in order to determine whether any interactions that occurred between Biogen and FDA review staff were inconsistent with FDA policies and procedures."

As we reported last month, not one member of the FDA Advisory Committee voted to approve Aduhelm, the agency decided to approve the therapy anyway. Since the decision, multiple members of the advisory committee have quit. And now Dr. Woodcock is demanding that a government watchdog investigate exactly how this travesty of medicinal regulation was allowed to move forward.

Shares of Biogen were off more than 3% in recent trade.

(Click on image to enlarge)

It's just the latest reminder that sometimes, "the science" isn't the top priority at the FDA.