An experimental attention deficit hyperactivity drug developed by SuperNus Pharmaceuticals has met the main goals of two late-stage studies, bolstering the company’s case that it could provide an alternative to currently available ADHD therapies. But shares of the Rockville, MD-based company promptly fell on concerns of whether the drug is any better than a widely available, similar generic.
SuperNus (NASDAQ: SUPN) said Thursday that patients treated with its drug, SPN-812, saw their scores improve, compared to a placebo, on a rating scale used to assess ADHD symptoms. However, analysts say those preliminary Phase 3 results don’t clearly distinguish the SuperNus compound from another marketed, generic drug that works in a similar way. Nonetheless, SuperNus says that with the early positive clinical data, it now plans to file for FDA approval of the drug in the second half of next year.
Shares of SuperNus fell roughly 13 percent, to $40 apiece, in early trading Thursday.
A 2016 study from the Centers for Disease Control and Prevention found that, as of 2016, 6.1 million U.S. children between two and 17 years of age were diagnosed with ADHD, which causes inattentiveness and hyperactivity. ADHD is commonly treated with stimulant medications, many of which are generic. But these drugs can cause side effects like headaches, high blood pressure, decreased appetite, and insomnia. There is also a non-stimulant approved to treat ADHD—atomoxetine (Strattera), a drug that is now also generic and cheap. SuperNus has been trying to show that its own non-stimulant drug SPN-812, which like atomoxetine is taken as a capsule, could be more effective.
The active ingredient in SPN-812, viloxazine hydrochloride, has been used for years in Europe where it is approved as an antidepressant. The drug is what’s known as a norepinephrine reuptake inhibitor. It blocks the absorption of the excitatory brain chemical norepinephrine, which is meant to help decrease hyperactivity and impulsive behaviors and improve a person’s attention span.
SuperNus reported results from two Phase 3 studies enrolling 790 children between 6 and 11 years of age who were randomized to receive either SPN-812 or a placebo. Each study tested two different doses of the drug. SuperNus says both trials met the main goal of improving ADHD symptoms. In one study testing low (100 mg) and medium (200 mg) doses of the SuperNus drug, the company reported -16.6 point and -17.7 point changes in scores, respectively, after six weeks, compared to a -10.9 point change for placebo patients. In a second study testing medium and high (400 mg) doses, SuperNus reported a -17.6 point and -17.5 point change, respectively, after eight weeks, compared to a -11.7 point change in the placebo group. The most common side effects seen were drowsiness, headache, decreased appetite, and upper abdominal pain.
The results may be good enough for SuperNus to seek FDA approval, but it’s not clear whether they will make SPN-812 commercially viable.
In a research note, Stifel analyst Annabel Samimy wrote that the one area where the SuperNus drug stood out from atomoxetine was how quickly it started to work—which is important because a big complaint with non-stimulant ADHD drugs is how long they take to kick in. But, Samimy added that the effect sizes seen in the studies were “not at a level that represents a clear standout” from the generic drug. SPN-812 “appears to have met its clinical hurdles, making it approvable, but we think the Street was seeking clearer points of differentiation,” she wrote.
SuperNus is testing its drug in two more Phase 3 studies in adolescents. Preliminary results from the first one are expected by the end of the month. The second should produce preliminary data by the end of the first quarter of 2019.