The Phase III, open-label extension study suggests EPX-100 has a “positive” risk/benefit profile for the treatment of Dravet syndrome, analysts at H.C. Wainwright & Co. said Tuesday.
Harmony Biosciences’ EPX-100 reduced monthly seizures by about half in a Phase III study of patients with Dravet syndrome.
“These results increase our confidence in the EPX-100 program,” analysts at H.C. Wainwright & Co. said in a note to investors on Tuesday. The analysts called the drug “a cornerstone of Harmony’s strategy” to complement the company’s excessive sleepiness drug Wakix.
The readout, H.C. Wainwright added, “represents a de-risking event for a key pipeline asset” for the biotech.
Tuesday’s data come from the open-label extension stage of the Phase III ARGUS study, a randomized, double-blinded and placebo-controlled trial that compared EPX-100 against placebo, looking at countable motor seizures per 28 days, a metric called CMS-28. Results showed that in patients who had been taking EPX-100 for at least 6 months in this extension phase, there was an “approximately 50% reduction” in CMS-28 from baseline.
All 29 patients who had completed the double-blind portion of the study continued on to the open-label extension phase, which H.C. Wainwright said is indicative of “a positive patient and physician view of the drug’s risk/benefit profile.”
More detailed data from the trial is scheduled to be presented on Dec. 8 at the American Epilepsy Society’s annual conference.
Aside from EPX-100’s preliminary efficacy, the ARGUS open-label phase also assessed the drug’s safety profile. There were 28 drug-related side effects and 11 serious adverse events, of which one was “possibly” linked to EPX-100, according to the study investigator. The H.C. Wainwright analysts called the drug’s safety profile “favorable” overall.
“While from a small, open-label cohort, this clinically meaningful efficacy signal provides strong validation for the program” in Dravet syndrome, H.C. Wainwright added. Harmony is also running the Phase III LIGHTHOUSE study for EPX-100, this time in Lennox-Gastaut syndrome, a rare and severe type of epilepsy in childhood. Both studies are pivotal, the analysts said, and are set to read out next year.
The Dravet win on Tuesday breaks somewhat of a losing streak for Harmony, which in September announced that its cannabidiol candidate ZYN002 failed a late-stage study in fragile X syndrome. In the Phase III RECONNECT trial, patients treated with ZYN002 showed no significant improvement in social avoidance. And though the biotech did not provide specific data at the time, it blamed the miss on a “higher than expected placebo response rate.”
In February, the FDA refused to accept Harmony’s supplemental application to expand Wakix into idiopathic hypersomnia. The biotech at the time did not reveal the reasoning behind the refusal.
