A Study to Evaluate the Safety and Pharmacokinetics of RC001 in Children With Dravet Syndrome

This is an open-label, single-center clinical study designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary efficacy of RC001 administered intrathecally in patients aged 2 to 18 years with Dravet syndrome. The study consists of two stages: Stage 1 (intra-subject dose escalation) and Stage 2 (fixed-dose multiple dosing). In Stage 1, three cohorts will be enrolled with a total of three participants. In Stage 2, a total of five participants will be enrolled to receive fixed-dose multiple administrations. Participants in both the dose-escalation stage and the fixed-dose multiple dosing stage may enter an extension phase after completion of the last dose, based on the investigator's assessment of efficacy and safety.

Inclusion criteria

• Patients aged 2-18 years with Dravet syndrome caused by SCN1A mutations, with onset before 12 months of age characterized by focal seizures, hemiclonic seizures, generalized tonic-clonic seizures, or myoclonic seizures, and with MRI excluding progressive neurological disease either historically or at screening. Enrolled participants will be assigned as follows: 1 participant aged 13-18 years, 1 aged 7-12 years, and 1 aged 2-6 years will undergo intra-subject dose escalation; 5 participants aged 2-12 years will receive fixed-dose multiple administrations.
• Seizure frequency requirements: at least 6 cumulative seizures within 12 weeks prior to the day of signing the ICF, and at least 2 seizures within 4 weeks prior to ICF signing. For participants in Stage 2 (fixed-dose multiple administration), seizure frequency must also be ≥4 within 4 weeks after ICF signing.
• Documented pathogenic or likely pathogenic variants in the SCN1A gene associated with Dravet syndrome.
• Prior treatment with at least one anti-epileptic intervention, including anti-seizure medications (ASM), ketogenic diet, or vagus nerve stimulation (VNS), with inadequate seizure control or discontinuation due to adverse events (AEs).
• Use of at least one ASM prior to screening, with a stable dose for at least 4 weeks before screening.
• All epilepsy-related treatments, including ASM and other interventions (ketogenic diet and VNS), must be stable for at least 4 weeks prior to screening and are expected to remain stable throughout the study (medications adjusted by body weight are allowed).
• Willingness to participate and provision of written informed consent.

Exclusion criteria

• Presence of other known pathogenic gene mutations causing Dravet syndrome, or SCN1A gain-of-function mutations reported in the literature and/or experimentally validated, including but not limited to: Ala23Glu, Thr162Ile, Thr226Met, Ser228Pro, Val229Leu, Ile236Val, Ile236Thr, Val250Leu, Leu263Val, Thr398Met, Ala420Val, Val422Leu, Ile883Thr, Leu893Phe, Ala989Thr, Thr1174Ser, Trp1204Arg, Ala1339Asp, Pro1345Ser, Pro1345Leu, Ser1346Pro, Ile1347Val, Val1481Ile, Ile1483Met, Gln1489Lys, Ile1498Thr, Ile1498Met, Phe1499Leu, Met1500Val, Arg1575Cys, Val1611Phe, Leu1624Pro, Arg1636Gln, Arg1648Cys, Leu1649Gln, Leu1660Ile, Phe1661Leu, Ala1669Glu, Leu1670Trp, Gly1674Arg, Phe1774Ser, Asp1866Tyr.
• Current maintenance treatment with anti-epileptic drugs primarily acting as sodium channel blockers, including but not limited to carbamazepine, oxcarbazepine, lamotrigine, lacosamide, or rufinamide.
• Ongoing neuromodulation therapy (e.g., responsive neurostimulation or deep brain stimulation), excluding vagus nerve stimulation (VNS).
• Receipt of gene therapy or cell therapy within 1 year prior to screening.
• Receipt of any vaccination within 12 weeks prior to screening.
• Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) >2× the upper limit of normal (ULN), or total bilirubin >1.5× ULN; renal insufficiency or serum creatinine >1.2× ULN.
• Presence of any severe uncontrolled disease other than Dravet syndrome.
• History of autoimmune disease, or uncontrolled infectious disease within 1 week prior to screening.
• History of brain or spinal cord disease (other than epilepsy, Dravet syndrome, or trauma), or history of bacterial meningitis.
• Spinal deformity or other conditions that may interfere with normal cerebrospinal fluid (CSF) flow, or implantation of a CSF shunt.
• Pregnant or breastfeeding females.
• Any other significant disease or condition that, in the investigator's judgment, may pose a risk to the patient, interfere with study results, or affect the patient's ability to participate in the study.