FDA partially lifts dosing hold on Stoke Therapeutics’ pediatric Dravet syndrome study

RNA player Stoke Therapeutics said Wednesday that the FDA partially lifted a clinical hold on a Phase I/IIa study in children and adolescents with Dravet syndrome, allowing the company to increase the tested dose of its lead drug.

Dawn Kalmar

Stoke spokesperson Dawn Kalmar tells Endpoints News the hold dates back to March 2020 when the company first got clearance to start Phase I/II studies testing candidate STK-001 in Dravet syndrome patients. The decision to put the partial hold in place was based on preclinical data, Kalmar added.

“At the time back in March of ‘20, they had limited dosing to 20 milligrams, multiple doses of 20 milligrams. Then in October of 2020, they allowed us to move to a 30 milligram dose. Then in September of 2021, they allowed us to move to a 45 milligram dose — and now we’re announcing that they’re allowing us to move to a 70 milligram dose, a single 70 milligram dose,” Kalmar said.

STK-001 is an antisense oligonucleotide candidate in the same class as Ionis and Biogen’s nusinersen, also known as Spinraza, for spinal muscular atrophy.

Kalmar added that the study has been ongoing since the hold, dosing patients in line with what the FDA’s hold required. And after turning in data from those dose levels, the FDA allowed Stoke to go to the next dosing level.

Dravet syndrome is a rare genetic epilepsy disorder characterized by frequent seizures in kids under 1 year of age. On top of developmental delays and sleeping disorders as additional symptoms, 10-20% of those with Dravet syndrome do not live beyond age 10.

The biotech has been conducting a sister study in the UK called ADMIRAL — which was initially approved at higher doses.

“We’ve been treating patients there with 30, and 45, and 70 milligrams in the UK,” Kalmar added.

Despite the update, shares of $STOK fell more than 8% after the market opened Wednesday morning.

Though some of the hold has been lifted, another part remains on the extension study, which is capped at 30 mg repeated dosing. The biotech is hoping it can finish the trial and move into Phase III sometime next year.

Stoke read out data from the trial last November, showing that a subgroup of six patients examined at 45 mg — who had all received three doses — had a median reduction of 55% in convulsive seizure frequency.

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