Supernus’s latest failure leaves its future looking dim

Supernus needs something to fill the gap left by its faltering epilepsy drug Trokendi XR, but SPN-810 isn’t it.

The past year has been tough for Supernus, and things are getting worse. The demise of the group’s biggest seller, Trokendi XR, looks to be approaching even more quickly than expected, and the company needs its pipeline projects to step into the breach.

Unfortunately for Supernus one of its hopefuls, the ADHD aggression candidate SPN-810, now looks like a dead duck. The asset had been expected to pick up the slack after Trokendi XR’s upcoming patent expiry, and with few other bright spots on the horizon Supernus might now have to look externally for growth.

A dimming outlook for Supernus
      Annual sales ($m)
Product/project Indication Status 2018 2024e
SPN-810 ADHD impulsive aggression Failed first phIII - 336
SPN-812 ADHD Filing imminent - 281
Oxtellar XR Epilepsy Marketed 85 261
Trokendi XR Epilepsy, migraine Marketed 315 67
SPN-604* Bipolar PhIII - -
SPN-809 Depression PhII ready - -
SPN-817 Epilepsy PhI - -
*Same active ingredient as Oxtellar XR; Source: EvaluatePharma, company presentation.

Investors do not seem convinced of the company’s chances of getting out of its current hole: Supernus’s stock, which had already fallen 30% since this time last year, is down 31% so far today after the double whammy of disappointing Trokendi third-quarter sales and the news of SPN-810’s phase III failure. 

However, the company refuses to be rushed into making a deal. During a conference call today its chief executive, Jack Khattar, said Supernus had long been looking for business development opportunities, but had not found any late-stage assets that would create value.

He added that the group did not want to end up overpaying for a deal. But bargains in the CNS sector are few and far between and Supernus, while well funded, does not have a huge amount of firepower, with $893m in cash and equivalents at the end of the third quarter.

Not so Super

Still, the company might need to do something soon after SPN-810, a dopamine antagonist, flunked its first pivotal test, the P301 trial. The study, in patients aged 6-11 with ADHD and impulsive aggression, did not meet its primary endpoint, the average weekly frequency of impulsive aggression episodes versus placebo: these fell by 59% and 48% with SPN-810 dosed at 36mg and 18mg respectively, compared with a 43% decline in the placebo arm.

Supernus claimed a statistically significant decrease in episodes with the higher dose of SPN-810 at the time of an interim analysis, citing a p value of 0.029 versus placebo. The company blamed variability in the latter part of the trial for the primary endpoint miss.

It is unclear whether the group will use this finding to justify pressing ahead with SPN-810. Data from a second phase III trial, called P302, should soon make the picture clearer: Supernus has stopped enrolment into that study early, at 98% of its target, and results are now due by the end of 2019. Mr Khattar said the company would consider the total data package before making a decision.  

Supernus needs SPN-810 to be a hit. It is due to file another non-stimulant ADHD candidate, SPN-812, in the US this month, but even if this is approved its commercial prospects are far from certain.

Three of four pivotal trials of SPN-812 read out positively. But the project has not been shown to be any better than Lilly’s non-stimulant ADHD drug Strattera, which lost patent protection in 2017, so could find it tough to compete (Supernus struggles to gain attention, March 28, 2019).

Talking of intellectual property, Trokendi XR is set to lose exclusivity in 2023, leaving Supernus limited time to find something to plug the gap. The group hopes to expand its epilepsy therapy Oxtellar XR into bipolar disease, where this is codenamed SPN-604, but there is no escaping the fact that, if SPN-810 is removed, the company's pipeline looks thin.

Supernus’s last acquisition, a $15m bet on Biscayne Neurotherapeutics, was hardly a game-changer. The company now needs to make a more decisive move.

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