Marinus Pharmaceuticals is gearing up for a phase 3 study after its epilepsy drug curbed seizures in patients with a rare, genetic disease that causes benign tumors to grow in various parts of the body, including the brain.
The treatment, ganaxolone, reduced the seizure frequency over four weeks in patients with tuberous sclerosis complex (TSC) by 16.6%, Marinus announced Tuesday afternoon. Nearly one-third (30.4%) of the 23 patients saw their seizure frequency cut in half. The 19 patients who experienced focal seizures—which affect one part of the brain rather than both sides of the organ—posted a 25.2% reduction in those seizures.
The data “shows an absolute seizure-reduction of 17%" for Marinus' therapy, according to a Wednesday morning note from Jefferies analyst Andrew Tsai. This compares to 30% to 50% seen with GW Pharma's Epidiolex and Novartis' Afinitor, but "other data points point to a more competitive drug profile” for Marinus, Tsai noted.
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Though GW Pharmaceuticals’ cannabis-based Epidiolex and Novartis’ Afinitor appear to be better at reducing seizures, Tsai pointed out that Marinus’ trial enrolled patients whose disease did not respond to those treatments, “so this population differs from that of previous studies.”
Current treatments for TSC, such as anti-seizure drugs, focus on controlling symptoms. Besides the brain, the disorder can cause the formation of benign tumors in organs including the skin, eyes, heart, kidneys and lungs. Patients may undergo surgery if tumors affect the ability of an organ to function.
Marinus is developing oral and intravenous formulations of ganaxolone for various seizure disorders, including CDKL5 deficiency (CDD), refractory status epilepticus and Lennox-Gastaut syndrome. The company filed the drug for FDA approval in CDD in July.
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Analysts see a 75% chance that the FDA will accept the filing and approve the drug in the first half of 2022, Tsai wrote.
In the run-up to approval, Marinus handed over the European rights to ganaxolone to Orion for $30 million upfront and up to $115 million in R&D reimbursement and milestone payments. Orion picked up rights to the drug in the European economic area, the U.K. and Switzerland for the treatment of CDD, TSC and refractory status epilepticus.