Background: GSP301 nasal spray is a fixed-dose combination of the antihistamine olopatadine hydrochloride and the corticosteroid mometasone furoate intended for seasonal allergic rhinitis (SAR) treatment. Objective: To evaluate the efficacy and safety of once-daily or twice-daily GSP301 in a ragweed pollen environmental exposure chamber. Methods: In this randomized, double-blind, double-dummy study, adults (18-65 years old) with SAR were equally randomized to 665 mg of olopatadine and 25 mg of mometasone (twice-daily GSP301), 665 mg of olopatadine and 50 mg of mometasone (once-daily GSP301), a US Food and Drug Administration−approved formulation of 137 mg of azelastine and 50 mg of fluticasone twice-daily (AzeFlu), a US Food and Drug Administration −approved formulation of 665 mg of olopatadine twice-daily, or placebo (twice-daily). During 2 visits (baseline and end of 14-day treatment), participants assessed SAR symptoms at specified time points. The primary end point-mean change from baseline in instantaneous total nasal symptom score (iTNSS) for twice-daily or oncedaily GSP301 vs placebo-was analyzed by analysis of covariance. Onset of action, ocular symptoms, and adverse events were assessed. Results: A total of 180 participants were randomized. Treatment with twice-daily or once-daily GSP301 provided statistically significant improvements in iTNSS vs placebo (twice-daily GSP301: least squares mean difference, ¡3.60; 95% confidence interval [CI], ¡4.89 to ¡2.30; once-daily GSP301: least squares mean difference, ¡3.05; 95% CI, ¡4.35 to ¡1.76; P < .0001 for both). Significant improvements in iTNSS with twice-daily GSP301 occurred by 10 minutes after dosing (¡1.26; 95% CI, ¡2.30 to ¡0.21; P = .02) and were maintained at all later time points except one (2.5 hours). Treatment-emergent adverse events occurred in 22.2%, 30.6%, 25.0%, 22.2%, and 16.7% of participants in the twice-daily GSP301, once-daily GSP301, AzeFlu, olopatadine, and placebo groups, respectively.
Conclusion:In an environmental exposure chamber model, twice-daily and once-daily GSP301 treatments were well tolerated and provided statistically significant and clinically meaningful SAR symptom improvement vs placebo. Trial Registration: ClinicalTrials.gov Identifier: NCT03444506