Supernus says SPN-812 hits main goal of two late-stage studies in ADHD

Supernus Pharmaceuticals announced Thursday that two Phase III studies of the experimental drug SPN-812 in children for the treatment of attention deficit hyperactivity disorder (ADHD) met their primary endpoints. The company said that it expects to seek FDA approval of the norepinephrine reuptake inhibitor in the second half of 2019. 

In the P301 study, 477 children aged six to 11 with a diagnosis of ADHD were randomly assigned to treatment with SPN-812, at a dose of 100 mg or 200 mg, or placebo once daily for five weeks. Meanwhile, 313 patients of the same age were randomised in the P303 trial to treatment with the drug at a dose of 200 mg or 400 mg, or placebo for seven weeks. In both studies, the main goal was the improvement of ADHD symptoms as assessed by the change from baseline to the end of the study in the ADHD Rating Scale-5 total score, while other endpoints included safety and tolerability.  

Top-line results showed that in both trials, SPN-812 led to significant improvements in the symptoms of ADHD from baseline to end of study versus placebo. Specifically, in P301, the low and high doses of the drug were linked to -16.6 point and -17.7 point changes, respectively, in the ADHD Rating Scale-5 total score from baseline to week six, compared to -10.9 for placebo. Supernus added that the study demonstrated fast onset of action, reaching significance for both doses as early as week one.

In addition, in the P303 trial, the low and high doses of SPN-812 were linked to -17.6 point and -17.5 point changes, respectively, in the ADHD Rating Scale-5 total score from baseline to week eight, versus -11.7 for placebo. In both studies, all doses of the drug were also associated with significant improvements of the hyperactivity/impulsivity and inattention subscales of the ADHD Rating Scale-5 compared to placebo.  

CEO Jack Khattar remarked "we believe these data…demonstrate that SPN-812 is a well-differentiated novel non-stimulant treatment option for many children with ADHD." Supernus indicated that top-line data from the Phase III P302 study of SPN-812 in adolescents with ADHD are expected by the end of December, while results from the second late-stage trial, called P304, in this indication are anticipated by the end of the first quarter of 2019.

SPN-812, whose active ingredient is viloxazine hydrochloride, belongs to the same class of drugs as Eli Lilly's Strattera (atomoxetine) and Shire's Intuniv (guanfacine). Commenting on the results for Supernus' compound, Stifel analyst Annabel Samimy said "onset of action proved more promising... This feature is important given that slow onset has been a primary complaint of other non-stimulants." However, Samimy said that although the studies reached significance, the results did not represent a clear standout from Strattera, with shares in Supernus falling more than 13 percent on the news. If approved, analysts predict that SPN-812 could generate sales of about $600 million in 2025.

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