- Supernus Pharmaceuticals has picked up an expected supplemental approval for Oxtellar XR as a monotherapy in the treatment of partial-onset seizures in adults and in children aged six and older. Oxtellar XR is an oral, once-daily drug previously approved for adjunctive therapy in this setting.
- According to Supernus, the monotherapy market could be around five-fold the size of the adjunctive therapy market, markedly increasing the potential sales for Oxtellar XR. Supernus plans to launch it as monotherapy in the first quarter of 2019 and take the drug into Phase 3 trials for bipolar disorder in the second half of that year.
- Oxtellar XR's net product sales were $20.4 million in the third quarter of 2018, up about 9% year over year. The drug accounts for around a fifth of the company's overall sales. The extension of the approval for Oxtellar XR will reduce the company's reliance on Trokendi XR, its only other marketed product.
Supernus hasn't been able to rebound its stock despite some favorable business developments this year.
A couple of weeks ago, it posted positive Phase 3 data from a pair of studies testing its investigational drug SPN-812 in patients with attention-deficit hyperactivity disorder (ADHD). The market wasn't impressed, however. In fact, shares slid down almost 12%.
Friday's news lifted Supernus shares just over 5%, though they still closed at $35.76 apiece — not far off its 52-week low of $34.90. Overall, company shares are down nearly 12% year to date.
Markets may be more tepid about the additional approval for Oxtellar XR (extended-release oxcarbazepine) due to its indication. David Steinberg, an equity analyst at Jefferies, explained in a recent note that epilepsy drugs historically ramp up slowly.
Oxtellar XR does have time on its side, though. It's covered by patents that expire no earlier than 2027, the same year as the patents protecting Supernus' top-selling Trokendi XR (extended-release topiramate). Jefferies predicts 2019 Oxtellar XR revenue of $95 million, while consensus estimates for 2019 sales sit at $100 million.
Supernus has already been successful at fighting off patent litigation. TWi Pharmaceuticals, a company based in Taiwan that focuses on "high barrier generics" in the U.S. market, has made an attempt at infringing the Oxtellar XR patents. Supernus received a ruling in September from the Federal Circuit supporting the New Jersey District Court's decision on the validity of the patents.