Regeneron, Sanofi Say Their Inflammation Drug Approved By FDA For Rare Skin Disease Affecting Elderly, But Retail Stays Dull

The injection is now approved in the U.S. to treat eight distinct diseases with underlying type 2 inflammation.

Regeneron Pharmaceuticals, Inc. (REGN) and Sanofi (SNY) on Friday announced that the U.S. Food and Drug Administration (FDA) has approved their Dupixent injection for the treatment of adult patients with bullous pemphigoid (BP) – a rare skin disease that primarily affects elderly patients.

BP is characterized by intense itch, painful blisters and lesions, and affects about 27,000 adults in the U.S. alone, as per Regeneron. The latest FDA approval was based on data from a late-stage study that evaluated the efficacy and safety of Dupixent compared to placebo in adults with moderate-to-severe BP.

In the study, 38.3% of patients who received Dupixent in addition to oral corticosteroids achieved clinically meaningful itch reduction compared to 10.5% in patients who received a placebo with oral corticosteroids.

The Dupixent injection, jointly developed by Sanofi and Regeneron, is now approved in the U.S. to treat eight distinct diseases with underlying type 2 inflammation, including diseases of the skin, gut, and respiratory system that affect a broad range of patients, from infants to the elderly.

Regeneron President George D. Yancopoulos said that the new approval extends the ability of Dupixent to transform treatment paradigms for people living with a variety of diseases with underlying type 2 inflammation, which includes common conditions like asthma and atopic dermatitis, to rarer ones such as eosinophilic esophagitis and prurigo nodularis.

More than 1,000,000 patients are being treated with Dupixent globally, according to the companies. In the first quarter of 2025, Dupixent brought in $3.67 billion in net sales, marking a growth of 19% year-on-year. This included $2.63 billion in net sales from the U.S. alone.

While Sanofi records global net sales of Dupixent, Regeneron records a share of profits from the sales as part of their agreement.

On Stocktwits, retail sentiment regarding Regeneron and Sanofi remained unchanged within ‘bearish’ territory over the past 24 hours.

While REGN stock is down by 28% this year, SNY stock is down by 1%.

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