Dupixent’s Dual FDA Wins Cement Sanofi and Regeneron’s Dominance in Autoimmune Dermatology

Sanofi (SAN) and Regeneron (REGN) are once again proving their prowess in the autoimmune space with the FDA’s April 18 approval of Dupixent (dupilumab) for chronic spontaneous urticaria (CSU), followed by a looming decision on its use in bullous pemphigoid (BP) by June 20. These milestones position Dupixent as a cornerstone therapy in dermatology, with sales poised to surpass $10 billion annually by 2027.

The CSU Breakthrough: A New Market of 300,000 Patients

The CSU approval marks the first major expansion of Dupixent’s label since 2023, targeting a U.S. patient population of approximately 300,000 adults whose symptoms persist despite standard-of-care H1 antihistamines. The pivotal LIBERTY-CSU CUPID trials demonstrated that Dupixent reduced severe itching by 8.6 points (vs. 6.1 with placebo) and cut hive activity by 15.8 points (vs. 11.2). Notably, 30% of patients achieved complete remission—double the placebo rate—offering a lifeline to those with refractory disease.

The drug’s existing approvals in atopic dermatitis, asthma, and nasal polyps already generate over $9 billion in annual revenue. CSU adds a $1.5–$2 billion opportunity in the U.S. alone, with global markets like Japan and the EU already onboard.

BP: A Priority Review for a Rare, Debilitating Disease

While CSU’s approval is final, the BP indication—under priority review—could unlock an additional $500 million in annual sales if approved. BP, a rare autoimmune blistering disease affecting ~27,000 U.S. adults, currently relies on steroids and immunosuppressants, which carry serious risks like infection and metabolic disorders.

The Phase 3 ADEPT trial showed Dupixent achieved sustained remission—defined as steroid-free remission with no relapse—in 20% of patients versus 4% for placebo. Secondary endpoints, including a 40% reduction in itch and 77% improvement in disease severity, further underscore its efficacy.

The Science Driving Dupixent’s Success

Dupixent’s mechanism—blocking IL-4 and IL-13 cytokines—targets the type-2 inflammation common in dermatological and respiratory conditions. Unlike steroids, it spares the immune system, minimizing infection risks. This specificity has enabled its use across seven indications, with over 1 million patients treated globally.

Risks and Regulatory Hurdles

While the CSU approval is a done deal, BP’s path is less certain. Adverse events like hypertension (observed in 3% of Dupixent patients) and blurred vision (2%) may prompt labeling restrictions. Additionally, BP’s small U.S. population could limit near-term sales growth. However, the priority review’s 6-month timeline and orphan drug designation suggest the FDA sees significant unmet need here.

Why Investors Should Take Notice

The dual approvals reinforce Dupixent’s franchise as a “one-drug, multi-condition” blockbuster. With over 60 clinical trials underway—including trials in pediatric CSU and BP—the drug’s addressable market could expand further.

Investors have already rewarded the news: Sanofi’s shares rose 3% in April, while Regeneron’s climbed 4%. Analysts project Dupixent’s sales to hit $11.5 billion by 2027, fueling Sanofi’s top-line growth amid declining revenue from its diabetes portfolio.

Conclusion: A Dermatology Giant with Legs

With CSU’s approval and BP’s pending nod, Dupixent is solidifying its position as the go-to biologic for type-2 inflammation-driven diseases. The drug’s scientific rationale, coupled with its broad label, gives Sanofi and Regeneron a 10-year lead over competitors. Even if BP approval is delayed, the CSU win alone adds $2 billion in annual sales—making this a rare win-win for investors.

For those watching the tape, the June 20 BP decision date is a key catalyst. Should it pass, look for Sanofi (SAN) and Regeneron (REGN) to hit fresh highs, with Dupixent’s total addressable market now exceeding $20 billion. This isn’t just a skin drug—it’s a franchise.