Dupixent ® (dupilumab) Demonstrated Superiority Over Xolair ® (Omalizumab) in Chronic Rhinosinusitis with Nasal Polyps (CRSwNP) in Patients with Coexisting Asthma in First-ever Presented Phase 4 Head-

Regeneron and Sanofi announced positive Phase 4 trial results showing Dupixent's superiority over Xolair in treating adults with severe chronic rhinosinusitis with nasal polyps (CRSwNP) and coexisting asthma. The EVEREST trial demonstrated Dupixent's statistically significant outperformance across all primary and secondary endpoints related to both CRSwNP symptoms (nasal polyp size, sense of smell, congestion) and asthma control, with improvements observed as early as 4 weeks. These findings, from the first head-to-head biologic trial in this patient population, reinforce Dupixent's efficacy by targeting IL-4 and IL-13, key drivers of type 2 inflammation.

Analysis

Regeneron (NASDAQ: REGN) and Sanofi (NASDAQ: SNY) presented compelling, late-breaking positive results from the EVEREST Phase 4 trial at the EAACI Annual Congress on June 15, 2025, demonstrating Dupixent's (dupilumab) superiority over Xolair (omalizumab) in treating adults with severe chronic rhinosinusitis with nasal polyps (CRSwNP) and coexisting asthma. This first-ever head-to-head respiratory trial with biologic medicines in this patient population showed Dupixent outperformed Xolair across all primary and secondary efficacy endpoints for CRSwNP and all asthma-related endpoints, with improvements observed as early as four weeks. Specifically, Dupixent achieved a 1.60-point superior reduction in nasal polyp size (p<0.0001a) and an 8.0-point superior improvement in ability to identify smells (p<0.0001a), both primary CRSwNP endpoints. For asthma, Dupixent showed a 150 mL greater improvement in lung function (pre-bronchodilator FEV1; p=0.003b) and a 0.48-point superior improvement in asthma control (p<0.0001b). These results reinforce Dupixent's efficacy, attributed to its mechanism of targeting IL-4 and IL-13, key drivers of type 2 inflammation. The safety profiles were generally similar, with overall adverse events at 64% for Dupixent and 67% for Xolair, and serious adverse events at 2% and 4% respectively, further supporting Dupixent's favorable risk-benefit profile in this direct comparison. Given Dupixent's established role in treating over one million patients globally across multiple indications, these data significantly strengthen its clinical value proposition and competitive stance against Xolair.

Key Decisions for Investors

• The demonstrated superiority of Dupixent over Xolair in the EVEREST trial is poised to enhance its market leadership and revenue generation potential for both Regeneron and Sanofi in the CRSwNP and coexisting asthma segment.
• Investors should evaluate the impact of these robust head-to-head trial results on Dupixent's future sales growth and its continued role as a pivotal value driver for both pharmaceutical partners.
• The combination of superior efficacy across multiple key endpoints and a comparable safety profile may accelerate physician adoption of Dupixent, potentially warranting a re-assessment of market expectations and valuations for Regeneron and Sanofi.