After SPN-820’s failure, Supernus is relying on its non-stimulant ADHD drug Qelbree and the recently approved Parkinson’s therapy Onapgo to sustain the company.
Supernus Pharmaceuticals’ drug candidate for treatment-resistant depression missed its primary endpoint in a Phase IIb study, the biotech revealed Tuesday.
Patients on SPN-820, an oral activator of the mTORC protein, saw a 12.3-point improvement in their scores on the Montgomery-Åsberg Depression Rating Scale (MADRS) at four weeks. Over the same time span, MADRS scores improved by 11.9 points in placebo comparators. The between-group difference failed to reach statistical significance, according to Supernus’ press announcement.
Similarly, “there was no treatment difference” between the investigational treatment and placebo in terms of secondary endpoint, the biotech added.
Supernus was down around 20% before the opening bell on Wednesday, as per SeekingAlpha.
Analysts at Jefferies anticipated the selloff, writing to investors on Tuesday evening that “we see [Supernus] trading down -25%” due to the readout.
CEO Jack Khattar in a statement said that the company is “disappointed” by these results, adding that it will “continue to analyze these data” and assess the path forward for SPN-820 with its development partner Navitor Pharmaceuticals.
SPN-820’s failure is somewhat surprising given that the drug candidate in October 2024 aced a Phase II study in major depressive disorder. When taken once every three days as an adjunct to baseline antidepressant medication, SPN-820 elicited a “clinically meaningful improvement” as early as four hours after dosing when measured using MADRS.
At the time, however, Jefferies cautioned that drugs that could work for both major depressive disorder and treatment-resistant depression are “rare”—a point the firm reiterated in its note on Tuesday.
Despite the mid-stage stumble, Jefferies still sees some reasons to be positive about Supernus’ prospects, particularly with the “continued uptake” of its non-stimulant ADHD drug Qelbree. “Emphasis for [Supernus] will be on growing its core business moving forward.”
In the near-term, Jefferies anticipates Qelbree to surpass its fourth-quarter 2024 sales consensus, putting it on-track to meet Jefferies’ projection of at least $500 million in peak sales for Supernus.
A little further out is the recently approved apomorphine hydrochloride injection Onapgo for advanced Parkinson’s disease, which Jefferies expects could be “another potential growth driver for 2025-26” once it launches. Onapgo opens a $100 million to $300 million opportunity for Supernus, according to the analyst.
