Dupixent’s FDA Approval in CSU: A Strategic Win for Regeneron and Sanofi
26min read The U.S. FDA’s recent approval of Dupixent® (dupilumab) for chronic spontaneous urticaria (CSU) in adults and adolescents aged 12 years and older marks a pivotal moment for Regeneron (NASDAQ: REGN) and Sanofi (NASDAQ: SAN). The April 18, 2025, decision, the first new targeted therapy for CSU in over a decade, underscores the drug’s growing dominance in type-2 inflammation-driven diseases. With over 300,000 U.S. patients needing better treatment options, this approval opens a new revenue stream for the duo, building on Dupixent’s already robust $10 billion annual sales across atopic dermatitis, asthma, and nasal polyps.
A Breakthrough in CSU Treatment
CSU, characterized by severe, persistent hives and itching unresponsive to standard antihistamines, significantly impairs quality of life. The approval is backed by the LIBERTY-CUPID Phase 3 trials, which demonstrated statistically significant reductions in weekly itch severity (ISS7) and hive activity compared to placebo. In Study A, 48% of Dupixent-treated patients achieved “well-controlled disease” (UAS7 ≤6) at 24 weeks, versus 13% on placebo, while Study C saw 33% vs. 12% improvement. These results validate Dupixent’s efficacy in a population where 50-70% of patients remain symptomatic despite maximal antihistamine therapy.
While Study B, evaluating patients refractory to omalizumab (Xolair), missed its primary endpoint, the FDA’s focus on the broader program’s success signals confidence in Dupixent’s profile. The drug’s safety profile—dominated by mild injection-site reactions—aligns with its established use in other indications, mitigating regulatory risks.
Market Potential and Competitive Landscape
The CSU indication directly competes with Roche’s omalizumab, which captured ~$1.5 billion in global sales in 2024. However, Dupixent’s mechanism—targeting interleukins 4 and 13—offers advantages over omalizumab’s IgE inhibition. Crucially, Dupixent’s approval fills a gap for patients unresponsive to omalizumab, as Study B’s failure highlights the need for alternative pathways. Analysts estimate the global CSU market at $500 million annually, with potential upside if the drug gains approval in pediatric patients or earlier lines of treatment.
The strategic value extends beyond CSU. Dupixent’s expanded label positions it as a cornerstone in a $20 billion type-2 inflammation market, with Sanofi and Regeneron already pursuing approvals in eosinophilic esophagitis and prurigo nodularis.
Financial Implications and Stock Outlook
The approval arrives as both companies face patent cliffs and pricing pressures in their legacy products. For Regeneron, Dupixent accounts for ~60% of revenue, while Sanofi derives ~20% of its biologics sales from the drug. The CSU indication could add $300–500 million in annual revenue by 2027, accelerating Dupixent’s path to becoming a $15 billion franchise.
Investors have already priced in optimism, with shares of Regeneron rising 15% since January 2025 on positive trial reads. However, the stock remains undervalued relative to peers, trading at ~12x 2025E earnings. Sanofi, meanwhile, has lagged due to broader portfolio concerns, but Dupixent’s momentum could narrow the gap.
Conclusion: A Foundation for Long-Term Growth
Dupixent’s CSU approval is more than a label expansion—it’s a testament to its versatility in treating systemic inflammatory diseases. With a proven track record in multiple indications and a robust pipeline, the drug is well-positioned to drive growth for years. The $300 million+ CSU market alone represents low-hanging fruit, but the true upside lies in leveraging the type-2 inflammation platform across dermatology, respiratory, and gastrointestinal conditions.
Analysts project Dupixent’s global sales to surpass $12 billion by 2026, with CSU contributing meaningfully to this growth. For investors, the FDA’s stamp of approval reinforces the drug’s status as a rare “once-in-a-generation” asset, capable of sustaining high margins and defying commoditization. In a crowded biotech landscape, Regeneron and Sanofi have secured a durable edge—one hive at a time.
