OBJECTIVE The objective of this study was to evaluate the efficacy, safety, and tolerability of DFN-02 - a nasal spray comprising sumatriptan 10 mg and a permeation-enhancing excipient (0.2% 1-O-n-Dodecyl-β-D-Maltopyranoside [DDM]) - for the acute treatment of migraine with or without aura in adults. BACKGROUND Prior work has shown that DFN-02, which contains only half the recommended adult dose of sumatriptan found in the original formulation (10 mg vs 20 mg), is more rapidly absorbed than commercial nasal spray of sumatriptan, with favorable pharmacokinetic and safety profiles. The efficacy of DFN-02 in the acute treatment of migraine has not been previously assessed. METHODS This was a multicenter, randomized, 2-period, double-blind, placebo-controlled efficacy, safety, and tolerability phase 2 study of DFN-02. Subjects with at least a 12 month history of episodic migraine, who averaged 2-8 attacks per month, with no more than 14 headache days per month and a minimum of 48 headache-free hours between attacks, were randomized (1:1) to receive DFN-02 or a matching placebo. Subjects were instructed to treat a single migraine attack of moderate to severe pain intensity. The primary efficacy endpoint, the proportion of subjects who were pain-free at 2 hours postdose in the first double-blind treatment period, was assessed with 2 protocol prespecified primary analyses: last observation carried forward (LOCF) and observed cases (OC). Secondary efficacy endpoints at 2 hours included pain relief; absence of the most bothersome symptom (MBS) among nausea, photophobia, and phonophobia; freedom from nausea, photophobia, and phonophobia. Sustained pain freedom from 2 through 24 hours postdose was also assessed. RESULTS Of 107 subjects randomized, 86.9% (N  =  93 [DFN-02, n = 50; placebo, n = 43]) had data in the first double-blind treatment period. The study met its primary endpoint; the proportion of subjects who were free from headache pain at 2 hours postdose, was statistically significantly higher in the DFN-02 group than in the placebo group in both prespecified primary analyses: LOCF (DFN-02, n = 21/48; placebo, n = 9/40; 43.8% vs 22.5%, P  =  .044) and OC (DFN-02, n = 21/48; placebo, n = 8/39; 43.8% vs 20.5%, P  =  .025). For secondary efficacy endpoints, at 2 hours postdose, DFN-02 was also statistically significantly superior to placebo for the proportion of subjects who had pain relief (83.3% vs 55.0%, P  =  .005); who were free of their MBS (70.7% vs 39.5%, P  =  .007); and who were free of nausea (78.3% vs 42.1%, P  =  .026), photophobia (71.8% vs 38.9%, P  =   .005), and phonophobia (78.1% vs 40.0%, P  =  .004). Compared with placebo, statistically significantly greater proportions of subjects who were treated with DFN-02 had sustained pain freedom from 2 through 24 hours postdose (38.9% vs 13.8%, P  =  .029). In total, 9.7% (9/93) of subjects reported a treatment-emergent adverse event during the study: 10.0% (5/50) of DFN-02 subjects in the first double-blind treatment period and 13.5% (5/37) of DFN-02 subjects in the second double-blind treatment period. The most common treatment-emergent adverse event with DFN-02 was dysgeusia (3/37 subjects in the second double-blind treatment period). CONCLUSIONS DFN-02 was shown to be effective, well tolerated, and safe in the acute treatment of episodic migraine. Additional studies are needed to confirm these preliminary results. (ClinicalTrials.gov Identifier: NCT02856802).