Supernus ADHD data doesn't win back investor optimism
- Supernus Pharmaceuticals on Thursday posted positive topline data from a pair of Phase 3 studies evaluating its investigational treatment for attention-deficit hyperactivity disorder. Yet the early results didn't win over investors, as the company's stock slid down almost 12% by market's close.
- Study P301 is testing 100 mg and 200 mg doses of SPN-812 while study P303 is testing 200 mg and 400 doses in children with ADHD. Compared to placebo, daily doses of the drug significantly improved ADHD symptoms from baseline to the end of the studies. Notably, onset of action reached statistical significance for the 100 mg and 200 mg doses as early as week one, whereas that took until week five in the P303 study. Levels of improvement from baseline were similar for all doses.
- Results from two Phase 3 studies of adolescent patients, P302 and P304, are expected before the end of 2018 and before the end of the first quarter in 2019, respectively. Supernus expects to file SPN-812 for approval in the back half of 2019 and launch in the latter half of 2020, pending approval.
The ADHD market has grown immensely due to increasing diagnoses. Treatment trends are moving from just addressing children to providing therapies for adolescents and adults. The U.S. held a 35% share of the global ADHD market in 2016 — and should continue to hold the largest share, according to a report from MarketResearchFuture, though the market in Asia Pacific is also growing.
Even though there are long-established stimulant and non-stimulant ADHD drugs such as Ritalin (methylphenidate), Adderall (levoamphetamine/dextroamphetamine), and Strattera (atomoxetine) on the market, the issues with side effects and the challenges of controlled drugs mean that there are still opportunities for companies taking innovative approaches.
SPN-812, for example, is a norepinephrine reuptake inhibitor with selective serotonin modulation activity.
Despite a predicted 2020 launch, Supernus investors don't seem super confident in SPN-812. This could be because of the difference in speed of onset between the two studies, and the lack of a connection between dose and response.
"The odd data point is that the successful highest dose of 400 mg did not perform better than the 200 mg dose. [Management] hypothesized that this effect could be due to all drug receptors being activated and thus full efficacy in children at 200 mg," said analyst David Steinberg of Jefferies in a Dec. 6 note.
Steinberg believes that SPN-812 is "approvable," forecasting peak sales of $400 million for the drug. What could make SPN-812 different, he suggests, is its consistency, low levels of adverse effects and especially its rapid onset.
"This dynamic could be a significant differentiating factor versus Strattera, which can take 6 weeks to take effect. In fact, Lilly’s website indicates 'optimal efficacy may take 12-24 weeks.' And compared to Intuniv, [SPN-812] demonstrated strong efficacy in both attention and hyperactivity vs just hyperactivity with Intuniv," Steinberg added.
Getting a drug to market for ADHD can still be challenging, as companies have stumbled at the final hurdle despite what they believe to be positive late-stage data.
Sunovion Pharmaceuticals' dasotraline, a dual-acting dopamine and norepinephrine reuptake inhibitor, received a Complete Response Letter in September that requested further efficacy and tolerability data. Sunovion said it intends to discuss next steps for its drug with regulators.
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