Sanofi and Regeneron Pharmaceuticals, Inc. announced that a Phase 2a proof-of-concept study of dupilumab met all primary and secondary endpoints in patients with moderate-to-severe chronic sinusitis with nasal polyps (CSwNP) who did not respond to intranasal corticosteroids. Dupilumab, a fully-human monoclonal antibody, is directed against the IL-4 receptor alpha subunit, which blocks signaling from both IL-4 and IL-13. IL-4 and IL-13 are key cytokines that are required for the initiation and maintenance of the Th2 (Type 2 helper T-cell) immune response, which is believed to be a critical pathway in allergic inflammation. In the study, dupilumab resulted in a statistically-significant improvement in the size of nasal polyps, as measured by endoscopic Nasal Polyp Score (NPS), the primary endpoint of the study. Statistically significant improvements in all secondary efficacy endpoints were also observed, including objective measures of sinusitis by CT scan, nasal air flow, and patient-reported symptoms (sense of smell, congestion, postnasal drip, runny nose and sleep disturbance). In a pre-specified exploratory analysis, dupilumab-treated patients who also had asthma demonstrated significant improvements in asthma control. The safety profile was consistent with previous studies. The most common AEs with dupilumab were injection site reactions, nasopharyngitis, oropharyngeal pain, epistaxis, headache and dizziness. The randomized, double-blind, placebo-controlled study enrolled 60 adult patients with moderate-to-severe CSwNP. Patients in the study received 300 milligrams (mg) of dupilumab or placebo administered once per week (QW) subcutaneously for 16 weeks, following an initial loading dose of 600 mg. All patients in the study also received a standard-of-care nasal corticosteroid spray. Patients were eligible for the study if they continued to have severe CSwNP despite standard treatment for at least one month. Fifty percent of patients in the study had received prior surgery for their condition. Asthma was also present in 58 percent of CSwNP patients in the study. The conditions are often co-morbid and symptoms/exacerbations are frequently interdependent.