Monday, Stoke Therapeutics Inc ( STOK ) released new data from two open-label Phase 1/2a studies and two open-label extension (OLE) studies of children and adolescents ages 2 to 18 with Dravet syndrome who were treated with STK-001. 

Dravet syndrome is a severe and progressive genetic epilepsy characterized by frequent, prolonged, and refractory seizures.

Data showed clinically meaningful effects, including substantial and durable reductions in convulsive seizure frequency and improvements in multiple measures of cognition and behavior.

STK-001 has been generally well-tolerated in studies to date.

Patients enrolled in these studies were highly refractory to treatment and taking the best available anti-seizure medicines: 85% of patients were taking at least three, and 54% were taking at least four medicines to control seizures. Half the patients in the studies were taking concomitant fenfluramine.

New data from a combined analysis of 19 clinically evaluable patients treated with one, two, or three doses of 70mg demonstrated substantial reductions in convulsive seizure frequency compared to baseline at three months and at six months after the last dose.

After one dose of 70mg, observed reductions in convulsive seizure frequency were 43% and 53%.

 After two or three doses of 70mg, observed reductions in convulsive seizure frequency were 85% and 74%.

Eligible patients who completed treatment in the Phase 1/2a studies continued treatment with STK-001 in one of two OLEs. 

Durable reductions in convulsive seizure frequency were observed throughout the course of treatment. 

This analysis only included patients who received >30mg of STK-001 in the Phase 1/2a studies and continued treatment with STK-001 (30mg or 45mg) every four months in the OLEs. 

Clinically meaningful improvements from baseline through 12 months were observed in multiple measures of cognition and behavior.

The company also announced an FDA clearance allowing patients to receive three doses of 70mg followed by continued dosing at 45mg. Based on this regulatory update and these data, the company plans to meet with regulatory agencies to discuss a registrational study that includes initial doses of 70mg followed by continued dosing at 45mg.

Price Action: STOK shares are up 74.60% at $11.35 during the premarket session on the last check Tuesday.