US Dravet Syndrome Launch Readiness

Refractory Dravet is a 1,400–2,000-patient market — and the bar is >40% additional seizure reduction over CBD plus fenfluramine.

Cannabidiol (Epidiolex, Jazz Pharmaceuticals, approved 2018) is the dominant Dravet standard of care, holding 55–60% of the Dravet-specific market on a six-year track record of physician loyalty and a WAC near $32,000/year once patient-assistance support is applied. Fenfluramine (Fintepla, UCB, approved 2020) has taken 25–30% share on a stronger responder rate, 62% seizure reduction in STUDIO 1 versus 38.9% for cannabidiol in GWPCARE1-4, but carries a REMS requirement: baseline, 3-month, 6-month and then twice-yearly echocardiography. An estimated 20–30% of eligible US Dravet patients cannot access fenfluramine because community paediatric neurology practices lack echo capacity, making REMS-free cardiac safety a structural access advantage for any new entrant, not just a clinical nicety.

Even with both drugs available, 35–40% of US Dravet patients, an estimated 1,400–2,000, remain inadequately controlled (less than 50% seizure reduction) on cannabidiol plus fenfluramine. This refractory cohort is the pre-launch target population: SCN1A-confirmed, typically still experiencing more than 20 seizures a month, and carrying a lifetime SUDEP risk of 2–18% that translates to an estimated 40–80 US Dravet deaths annually. Comorbidity burden is high: intellectual disability in 70–80%, autism-spectrum features in 20–30%, and gait abnormalities in 70%. Caregiver burden averages 60-plus hours a week, evidence that FDA and payers increasingly expect alongside seizure-frequency data in Dravet trial design.

Prior-authorization criteria for Dravet agents are already set: Dravet diagnosis (clinical or SCN1A-confirmed), at least four seizures a month, failure of two or more prior anti-seizure medications, and a paediatric epilepsy specialist's sign-off. A new agent will inherit this framework rather than negotiate a new one. The payer mix is roughly half commercial and 45% Medicaid, so a state-by-state Medicaid access strategy has to exist at launch, not 18 months after. ICER has not yet conducted a Dravet value assessment, which is a genuine pre-launch opening: engaging ICER proactively, before payers anchor to a competitor's cost-effectiveness framework, lets a new entrant help set the value narrative rather than react to it. Pricing between the two incumbents ($60,000–80,000/year) with a REMS-free profile and a responder rate at or above 60% produces the most favourable cost-effectiveness case available in Dravet today.