SCN8A Developmental and Epileptic Encephalopathy SyndromePhase 2NCT04873869
Study to Evaluate NBI-921352 as Adjunctive Therapy in Subjects With SCN8A Developmental and Epileptic Encephalopathy Syndrome (SCN8A-DEE)
A Phase 2 study testing NBI-921352 in people with SCN8A Developmental and Epileptic Encephalopathy Syndrome, run by Neurocrine Biosciences at 4 sites in United States.
Trial summary
The objective of this study is to assess the efficacy, safety, and pharmacokinetics of NBI-921352 as adjunctive therapy for seizures in subjects with SCN8A Developmental and Epileptic Encephalopathy Syndrome (SCN8A-DEE). Read more about this study
- Who is it for?
- Ages 2 to 21 years
- Conditions the study is for
- SCN8A Developmental and Epileptic Encephalopathy Syndrome
- What is being tested?
- NBI-921352
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 8 participants
- Where
- 4 sitesUnited States
- Study dates
- 31 Jan 2022to 17 Mar 2023
- Phase
- Phase 2
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 2 to 21 years
- All sexes
- No healthy volunteers
- Child, Adult
Who may be able to join
- Male or female 2 to 21 years of age, inclusive.
- Have a diagnosis of SCN8A-DEE supported by both clinical and genetic findings
- Have on average at least 1 countable motor seizure per week and not be seizure-free for more than 20 consecutive days
- Being treated with at least 1 other antiseizure medication (ASM), but no more than 4 ASMs
- Have failed to achieve seizure freedom with at least 2 ASMs
- Must be using a nocturnal alerting system or practice consistent with standards of care at the time of screening and continue to use this for the duration of the study
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- Must have an adequate rescue medication regimen per the investigator's judgment in place at the time of screening and for the duration of the study
- Have a body weight of at least 10 kg
- The subject's parent/caregiver is able to accurately identify seizure types, especially countable motor seizures (defined as GTCS, tonic, atonic or FOS with noticeable motor component) and is able to complete seizure diary
Who cannot join
- Have previously been enrolled in this study and received blinded treatment
- Have participated in an interventional clinical trial < 30 days prior to screening
- Have symptoms that would be more consistent with another epilepsy disorder such as Dravet syndrome (eg, fever-induced episodes of status epilepticus, frequent myoclonic seizures, worsening on sodium channel blockers, absence seizures with generalized spike-and-wave EEG as the sole seizure type)
- Are currently receiving cannabinoids or medical marijuana except Epidiolex/Epidyolex, unless approved by the Sponsor
- Are currently taking systemic steroids (excluding inhaled medication for asthma treatments and intranasal steroids for allergies). If subject has received these medications in the past, must be off these medications for at least 3 months prior to the screening visit and these drugs may not be initiated during the duration of the study. Intermittent steroids to treat nonepilepsy related diseases (such as allergies or dermatological conditions) are not exclusionary
- Have a history of moderate or severe head trauma or other neurological disorders or systemic medical diseases that are, in the investigator's opinion, likely to affect nervous system functioning
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- Have a clinically significant medical condition or chronic disease, that in the opinion of the investigator would preclude the subject from participating in and completing the study or that could confound interpretation of study outcome
- Have clinically significant abnormal vital signs at the screening visit as determined by the investigator
- Have one or more clinical laboratory test values outside the reference range, based on blood samples taken at the screening visit, that are of potential risk to the subject's safety as determined by the investigator
- Have, at the screening visit, an electrocardiogram (ECG) finding of a corrected QT interval using Fridericia's formula (QTcF) > 450 msec or presence of any significant cardiac abnormality.
Trial locations and contacts
4 sites in 1 country.
United States4 sites
Cook Children's Medical Center
Fort Worth, Texas, 76104
University of Rochester
Rochester, New York, 14642
UCSF Medical Center
San Francisco, California, 94158
Children's National Hospital
Washington D.C., District of Columbia, 20010
About this study
Official title: A Phase 2 Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Efficacy, Safety, Tolerability, and Pharmacokinetics of NBI-921352 as Adjunctive Therapy in Subjects With SCN8A Developmental and Epileptic Encephalopathy Syndrome (SCN8A-DEE)
The objective of this study is to assess the efficacy, safety, and pharmacokinetics of NBI-921352 as adjunctive therapy for seizures in subjects with SCN8A Developmental and Epileptic Encephalopathy Syndrome (SCN8A-DEE).
- Being tested
- NBI-921352, Placebo
- Keywords
- Epilepsy, Sodium channel, voltage-gated, type VIII, alpha subunit (SCN8A), NaV1.6 inhibitor
- Medical subject headings
- Epilepsy
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
NBI-921352Drug
Administered orally
PlaceboDrug
Administered orally
| Study group | Role | What they receive |
|---|---|---|
| Placebo | Placebo comparator | Participants will receive matching placebo for up to 18 weeks. Receives: Drug: Placebo |
| NBI-921352 | Experimental | In the first 6 weeks participants will receive increasing doses of NBI-921352 (Titration Period) based on weight, followed by 10 weeks of treatment at their final tolerated dose (Maintenance Period) and 2 weeks of treatment with decreasing doses (Taper Period). Receives: Drug: NBI-921352 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Percentage Change From Baseline in 28-day Seizure Frequency for Countable Motor Seizures During the 16-week Treatment Period
Measured: Planned time frame: Baseline to Week 16
Secondary outcomes (8)
Percentage of Participants With a Treatment Response
Treatment response was defined as a ≥50% decrease from baseline in 28-day seizure frequency for countable motor seizures during the treatment period of the study.
Measured: Planned time frame: Baseline to Week 16
Percentage Change From Baseline in 28-day Seizure Frequency for Countable Motor Seizures During the 10-week Maintenance Period
Measured: Planned time frame: Baseline, Week 6 to Week 16
Percentage of Participants With a ≥ 25%, ≥ 75%, or 100% Treatment Response During the 16-week Treatment Period
Treatment response was defined as a ≥25%, ≥50%, ≥75%, or 100% decrease from baseline in 28-day seizure frequency for countable motor seizures during the treatment period of the study.
Measured: Planned time frame: Baseline to Week 16
Percentage of Participants With a ≥25%, ≥50%, ≥75%, or 100% Treatment Response During the 10-week Maintenance Period
Treatment response was defined as a ≥25%, ≥50%, ≥75%, or 100% decrease from baseline in 28-day seizure frequency for countable motor seizures during the treatment period of the study.
Measured: Planned time frame: Baseline, Week 6 to Week 16
Clinical Global Impression of Change (CGIC) Score at Each Visit During the 16-week Treatment Period
The CGIC scale, which is based on a 7-point scale (range: 1=very much improved to 7=very much worse), was used to rate the overall global improvement since the initiation of study treatment dosing, as rated by the investigator (or qualified designee).
Measured: Planned time frame: Up to Week 16
Parent/Caregiver Global Impression of Change (GIC) Score at Each Visit During the 16-week Treatment Period
The GIC scale was used to assess the parent/caregiver's impression of change in the participant's overall condition since starting study treatment and was rated on a 7-point scale (1=very much improved to 7=very much worse).
Measured: Planned time frame: Up to Week 16
Change From Baseline in Clinical Global Impression of Severity (CGIS) Scores at Each Visit During the 16-week Treatment Period
The CGIS scale was used to assess overall severity on a 5-point scale (range: 1=normal, not at all ill to 5=among the most extremely ill).
Measured: Planned time frame: Baseline to Week 16
Change From Baseline in Parent/Caregiver Global Impression of Severity (GIS) Scores at Each Visit During the 16-week Treatment Period
The GIS scale was used to assess overall severity on a 5-point scale (range: 1=none to 5=very severe).
Measured: Planned time frame: Baseline through Week 16
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted5 May 2021
- Study start31 Jan 2022
- Primary completion17 Mar 2023
- Study completion17 Mar 2023
Why it stopped: This study was prematurely terminated due to sponsor decision.
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for SCN8A Developmental and Epileptic Encephalopathy SyndromeStudies of the same condition, open and under way.
- More trials run by Neurocrine BiosciencesThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind
- Who is masked
- Participant, Care provider, Investigator
- Enrolment
- 8 participants (actual)
Sponsor and investigators
- Lead sponsor
- Neurocrine Biosciences
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Clinical Development Lead, Study director, Neurocrine Biosciences
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04873869
- Sponsor's protocol ID
- NBI-921352-DEE2012
- Other IDs
- 2020-003140-83
- Status last verified
- Sep 2025
- First submitted
- 30 Apr 2021
- Last updated
- 16 Oct 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 16 Oct 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 2 Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Efficacy, Safety, Tolerability, and Pharmacokinetics of NBI-921352 as Adjunctive Therapy in Subjects With SCN8A Developmental and Epileptic Encephalopathy Syndrome (SCN8A-DEE)
- ClinicalTrials.gov ID
- NCT04873869
- Acronym / sponsor ID
- NBI-921352-DEE2012
- Keywords
- Epilepsy, Sodium channel, voltage-gated, type VIII, alpha subunit (SCN8A), NaV1.6 inhibitor
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: This study was prematurely terminated due to sponsor decision.
- Enrolment
- 8 participants (actual)
- Lead sponsor
- Neurocrine BiosciencesIndustry (pharma, biotech, devices)
- Study start
- 31 Jan 2022 (actual)
- Primary completion
- 17 Mar 2023 (actual)
- Study completion
- 17 Mar 2023 (actual)
- First posted
- 5 May 2021 (actual)
- Results
- Posted 16 Oct 2025
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The objective of this study is to assess the efficacy, safety, and pharmacokinetics of NBI-921352 as adjunctive therapy for seizures in subjects with SCN8A Developmental and Epileptic Encephalopathy Syndrome (SCN8A-DEE).
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, care provider, investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Placebo | Placebo comparator | Drug: PlaceboParticipants will receive matching placebo for up to 18 weeks. |
| NBI-921352 | Experimental | Drug: NBI-921352In the first 6 weeks participants will receive increasing doses of NBI-921352 (Titration Period) based on weight, followed by 10 weeks of treatment at their final tolerated dose (Maintenance Period) and 2 weeks of treatment with decreasing doses (Taper Period). |
Who may qualify
- Ages
- 2 to 21 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult
Key inclusion criteria (9 listed)
- Male or female 2 to 21 years of age, inclusive.
- Have a diagnosis of SCN8A-DEE supported by both clinical and genetic findings
- Have on average at least 1 countable motor seizure per week and not be seizure-free for more than 20 consecutive days
- Being treated with at least 1 other antiseizure medication (ASM), but no more than 4 ASMs
- Have failed to achieve seizure freedom with at least 2 ASMs
Key exclusion criteria (10 listed)
- Have previously been enrolled in this study and received blinded treatment
- Have participated in an interventional clinical trial < 30 days prior to screening
- Have symptoms that would be more consistent with another epilepsy disorder such as Dravet syndrome (eg, fever-induced episodes of status epilepticus, frequent myoclonic seizures, worsening on sodium channel blockers, absence seizures with generalized spike-and-wave EEG as the sole seizure type)
- Are currently receiving cannabinoids or medical marijuana except Epidiolex/Epidyolex, unless approved by the Sponsor
- Are currently taking systemic steroids (excluding inhaled medication for asthma treatments and intranasal steroids for allergies). If subject has received these medications in the past, must be off these medications for at least 3 months prior to the screening visit and these drugs may not be initiated during the duration of the study. Intermittent steroids to treat nonepilepsy related diseases (such as allergies or dermatological conditions) are not exclusionary
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| NBI-921352Administered orally | Drug | NBI-921352 |
| PlaceboAdministered orally | Drug | Placebo |
Primary outcome
Percentage Change From Baseline in 28-day Seizure Frequency for Countable Motor Seizures During the 16-week Treatment Period
Time frame: Planned time frame: Baseline to Week 16
8 secondary outcomes
Percentage of Participants With a Treatment Response
Time frame: Planned time frame: Baseline to Week 16
Percentage Change From Baseline in 28-day Seizure Frequency for Countable Motor Seizures During the 10-week Maintenance Period
Time frame: Planned time frame: Baseline, Week 6 to Week 16
Percentage of Participants With a ≥ 25%, ≥ 75%, or 100% Treatment Response During the 16-week Treatment Period
Time frame: Planned time frame: Baseline to Week 16
Percentage of Participants With a ≥25%, ≥50%, ≥75%, or 100% Treatment Response During the 10-week Maintenance Period
Time frame: Planned time frame: Baseline, Week 6 to Week 16
Clinical Global Impression of Change (CGIC) Score at Each Visit During the 16-week Treatment Period
Time frame: Planned time frame: Up to Week 16
Parent/Caregiver Global Impression of Change (GIC) Score at Each Visit During the 16-week Treatment Period
Time frame: Planned time frame: Up to Week 16
Change From Baseline in Clinical Global Impression of Severity (CGIS) Scores at Each Visit During the 16-week Treatment Period
Time frame: Planned time frame: Baseline to Week 16
Change From Baseline in Parent/Caregiver Global Impression of Severity (GIS) Scores at Each Visit During the 16-week Treatment Period
Time frame: Planned time frame: Baseline through Week 16
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Oct 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Individual participant dataSharing planned: No
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Clinical Development Lead study director
Neurocrine Biosciences
4 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing NBI-921352 in people with SCN8A Developmental and Epileptic Encephalopathy Syndrome, run by Neurocrine Biosciences at 4 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 9 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 16 Oct 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 4 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 16 Oct 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Percentage Change From Baseline in 28-day Seizure Frequency for Countable Motor Seizures During the 16-week Treatment Period (time frame: Planned time frame: Baseline to Week 16). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Oct 2025; AzTrials last refreshed its copy on 26 Oct 2026.