Disc Medicine, Sanofi, Eli Lilly Shares Slip On Reports Of FDA Increasing Review Time For Drugs Granted Priority Review Vouchers

Reuters reported on Thursday that the FDA delayed the review of Disc Medicine’s experimental drug for the treatment of Erythropoietic Protoporphyria (EPP) after its scientists flagged safety and efficacy concerns.

• FDA is slated to decide on Disc Medicine's Bitopertin by February. 
• Approval for Lilly’s obesity pill is expected by April 10.
• The FDA has also stalled the review of Sanofi’s Tzield for late-stage type 1 diabetes by more than a month over adverse event reports, Reuters said.

Shares of Dis Medicine (IRON) fell 7% on Thursday after the U.S. Food and Drug Administration (FDA) reportedly delayed review of its drug Bitopertin despite choosing it for fast track review under a new voucher program.

Reuters reported on Thursday, citing internal documents, that the FDA delayed the review of the company’s experimental drug for treatment of Erythropoietic Protoporphyria (EPP) after its scientists flagged safety and efficacy concerns. EPP is a rare, inherited metabolic disorder causing extreme sensitivity to sunlight and artificial light, leading to immediate, painful skin reactions like burning, redness, and swelling.

The reviewers pushed the drug’s potential approval by two weeks to Feb. 10 as they examine whether it has abuse risks. The agency also has concerns if pain-free time in the sun is a statistically solid measure of efficacy or if other data can justify approval, the report said.

Disk Medicine’s Bitopertin is one of the 18 drugs to currently have been tapped for fast review by the FDA under its Commissioner's National Priority Voucher program announced in June 2025. The program aims to reduce FDA assessment time to one to two months from the standard 10 to 12 months.

Sanofi Faces Longer Delay

The FDA has also stalled the review of Sanofi’s (SNY) Tzield for late-stage type 1 diabetes by more than a month over adverse event reports, Reuters said.

The agency is considering the death of a patient while taking the drug and also evaluating two reports related to seizure and blood clotting. The agency was initially slated to decide on the application by Nov. 21.

Lilly’s Weight-Loss Drug Approval Now Slated For Q2

Other drugs to face delays beyond the original target date include Boehringer Ingelheim's zongertinib for lung cancer and Eli Lilly’s (LLY) weight-loss pill. While zongertinib approval is now expected in mid-February, approval for Lilly’s obesity pill is expected by April 10, later than its initial first quarter (Q1) estimate, Reuters said.

LLY shares traded 4% lower at the time of writing while SNY shares fell 1%.

According to Reuters, at least seven drugs selected for priority review have started the approval process. While most of the reviews for the drugs selected for the program are slated to start this year, others are scheduled for 2027 and 2028.

Only one antibiotic drug has been approved under the program as of date called Augmentin XR.

How Did Stocktwits Users React?

On Stocktwits, retail sentiment around IRON and SNY stocks trended in the ‘Neutral’ territory at the time of writing. Retail sentiment around LLY, however, rose from ‘bullish’ to ‘extremely bullish’ over the past 24 hours.

A Stocktwits user dismissed the delay report as a “short term hiccup.”

Another opined that the selloff in IRON shares is a buying opportunity.

DISC stock has gained 18% over the past 12 months.   

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