SPN-812 (extended-release viloxazine) is a structurally distinct, bicyclic, Serotonin Norepinephrine Modulating Agent (SNMA) in development as a treatment for attention-deficit/hyperactivity disorder (ADHD) in children and adolescents. This Phase 3, randomized, double-blind study (P303) evaluated the efficacy and safety of once-daily SPN-812 at doses of 200 and 400 mg compared to placebo in children ages 6-11yrs with ADHD.

Inclusion criteria required subjects have a confirmed Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) ADHD diagnosis, ADHD-Rating Scale-5 (ADHD-RS-5) score ≥28, Clinical Global Impression-Severity score ≥4, and be free of ADHD medication ≥1 week before randomization. Subjects were enrolled at 31 study sites in the United States. Subjects (N=313) were randomized 1:1:1 to placebo:200 mg SPN-812:400 mg SPN-812. Treatment included up to 3 weeks of titration and 5 weeks of maintenance (intent-to-treat population: N=301; placebo=97, 200 mg=107, 400 mg=97). The primary efficacy endpoint was change from baseline (CFB) at end of study (EOS) in ADHD-RS-5 total score. Key secondary endpoints included Clinical Global Impression-Improvement (CGI-I) score at EOS, and CFB at EOS in Conners 3-Parent Short Form (Conners 3-PS) Composite T-score and in Weiss Functional Impairment Rating Scale-Parent Form (WFIRS-P) total average score. Safety assessments included adverse events (AEs) among other measures.

Compared to placebo, a significantly greater improvement in ADHD-RS-5 total score was observed in the 200 mg and 400 mg SPN-812 treatment group at EOS (p=0.0038, p=0.0063; respectively). Significant improvement in CGI-I score at EOS for both 200 mg and 400 mg SPN-812 was also observed (p=0.0028, p=0.0099; respectively). Significant improvement was observed for the 200 mg SPN-812 dose compared to placebo in the Conners 3-PS Composite T-score (p=0.0064), but not for the 400 mg dose (p=0.0917). No significant improvement was observed in either dose group in the WFIRS-P total average score (p=0.0651, p=0.1680; respectively). The most common (≥5%) treatment-related AEs were somnolence, decreased appetite, fatigue, headache, and upper abdominal pain.

In this study, SPN-812 met the primary objective for both the 200 and 400 mg doses and the key secondary objective (CGI-I) for both the 200 and 400 mg doses with statistical significance. A second key secondary objective (Conners 3-PS) for the 200 mg dose was also met. AE-related dropouts were ≤5%, indicating SPN-812 treatment was well tolerated.

This study is an encore of a poster presentation at the 2019 Annual Meeting of the American Academy of Child and Adolescent Psychiatry (AACAP).

This research was funded by Supernus Pharmaceuticals, Inc., Rockville, MD.