FDA to review Dupixent sBLA for bullous pemphigoid

Sanofi and Regeneron are aiming to expand the use of their highly successful biologic treatment, Dupixent (dupilumab), to include the treatment of bullous pemphigoid (BP), a rare autoimmune skin disorder. The United States Food and Drug Administration (FDA) has accepted their supplemental biologics license application for priority review, and a decision is anticipated by June 20, 2025. If approved, Dupixent would be the first targeted therapy for BP, which currently lacks FDA-approved treatments.

Bullous pemphigoid predominantly affects older adults, causing large, fluid-filled blisters when the immune system mistakenly attacks proteins in the skin’s basement membrane. This results in inflammation and separation of the skin. Presently, the standard treatment involves using corticosteroids like prednisone, which manage symptoms but come with significant side effects such as weight gain, elevated blood sugar, and mood alterations.

The FDA's decision to review the application is informed by findings from the Phase II/III LIBERTY-BP ADEPT trial. This study assessed the effectiveness of Dupixent in BP patients, enrolling 106 participants. Those receiving Dupixent at a dose of 300mg biweekly showed a fivefold increase in sustained disease remission rates (20%) compared to the 4% remission rate in the placebo group. Remission was characterized by a complete clinical response after tapering off standard oral corticosteroids by the 16th week, with no relapses or need for additional therapy during the 36-week trial. Dupixent also outperformed placebo in reducing disease severity and alleviating significant itchiness, among other secondary outcomes.

Dupixent functions as a fully human monoclonal antibody that blocks the signaling pathways of interleukin-4 (IL-4) and interleukin-13 (IL-13), which are instrumental in type 2 inflammation. It is already approved in the United States for six indications, including atopic dermatitis, asthma, and chronic obstructive pulmonary disease (COPD).

Sanofi's financial report for the fourth quarter of 2024 revealed that Dupixent exceeded its annual sales target of €13 billion, reaching $14.15 billion. It is projected to generate $25 billion in global sales by 2030, according to GlobalData’s Pharma Intelligence Center.

Despite Dupixent's commercial triumph, there has been friction between Regeneron and Sanofi. Regeneron initiated legal action against its partner, accusing Sanofi of withholding crucial commercialization information in violation of their agreement. Specifically, Regeneron contends that Sanofi failed to provide details regarding pharmacy benefit manager contracting for Dupixent, presumably to avoid revealing bundling arrangements with other immunology medications. The lawsuit was initially filed in November 2024 and updated in December, becoming public through Regeneron’s annual SEC filing in February 2025.

Regeneron and Sanofi have been working together on Dupixent since 2007, focusing on the drug’s development and commercialization. Despite the current legal dispute, Dupixent remains a vital asset for both companies. Regeneron is seeking a declaratory judgment, injunctive relief, and financial compensation. In 2024, Dupixent became Regeneron’s best-selling product, surpassing its eye treatment, Eylea (aflibercept).