Disc Medicine’s stock fell sharply following a report that Vinay Prasad, director of the FDA’s biologics center, is skeptical about the efficacy of bitopertin, a drug candidate under review for treating porphyria. STAT reported that Prasad became personally involved in the review process after the FDA team responsible for Disc’s application requested more time to evaluate the filing. The application is being reviewed under the Commissioner’s National Priority Voucher (CNPV) program, which aims to expedite assessments within one to two months.
Following publication of the report, Disc shares dropped by as much as 21.7% before closing down 11.5% at $80.04 on Friday.
Disc executives addressed analysts in a call on Friday to discuss the situation. Truist Securities analysts noted in a message to investors that Disc management was “blindsided” by the STAT report and described Prasad’s involvement as unprecedented. “We are in uncharted territory,” Truist analysts said. “While we think Prasad’s personal involvement in any review naturally warrants some caution, the information available today is far too limited to draw a definitive conclusion on the potential outcome.”
Both Truist and BMO Capital Markets analysts indicated they left the call with unanswered questions since Disc executives could not provide further clarity. According to Truist, Disc’s team has had no direct contact with Prasad but understands he participates in CNPV reviews using a “tumor board”-style approach. The extent of his role and influence remains unclear, especially since bitopertin is a small molecule drug and thus outside Prasad's typical remit as head of biologics.
BMO analysts cited Disc executives who said that so far, the FDA has not communicated any efficacy concerns directly to them and has not indicated an advisory committee would be needed for this decision. While procedural questions regarding efficacy have been raised—such as clarifying correlations between biomarkers and clinical benefit—BMO reported that interactions with FDA officials remain positive.
Truist analysts mentioned that Disc acknowledged there may be some truth to reports about timing constraints affecting CNPV procedures but stated their regulatory team believes they are still on track for the previously announced CNPV date.
Despite uncertainties surrounding approval timing or possible outcomes if authorization is delayed or denied, both BMO and Truist expressed optimism about bitopertin's chances for approval. If rejected, Truist said next steps are unclear due to how new the CNPV program is but noted that Disc expects a complete response letter from the FDA if necessary.
Recent policy changes at the FDA have affected various aspects of agency operations this year, including rare disease guidance and efforts to improve efficiency and domestic manufacturing processes relevant to biopharma companies such as Disc Medicine (https://www.biospace.com/article/fda-policy-tracker-2025-was-a-year-of-change/).
“We are in uncharted territory,” Truist analysts said. “While we think Prasad’s personal involvement in any review naturally warrants some caution, the information available today is far too limited to draw a definitive conclusion on the potential outcome.”
