SCN8A Developmental and Epileptic Encephalopathy SyndromePhase 2NCT05226780
Extension Study to Evaluate How Safe and Tolerable NBI-921352 is as an Adjunctive Therapy for Participants With 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
Extension study to evaluate how safe and tolerable the drug NBI-921352 is when used as adjunctive therapy in participants with SCN8A developmental and epileptic encephalopathy syndrome (SCN8A-DEE). Read more about this study
- Who is it for?
- Ages 2 to 22 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?
- No, everyone receives an active treatment
- How many people
- 8 participants
- Where
- 4 sitesUnited States
- Study dates
- 12 Jul 2022to 12 Nov 2025
- Phase
- Phase 2
- Are there results?
- None posted in the registry
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 22 years
- All sexes
- No healthy volunteers
- Child, Adult
Who may be able to join
- For Participants Who Participated in NBI-921352-DEE2012:
- Written or oral pediatric assent from the participant and written informed consent from the participant's parent(s) or legal guardian(s) for pediatric participants and adult participants who are not capable of providing consent. Adult participant who are ≥18 years of age and capable of providing consent should sign an Informed Consent Form (ICF).
- Completed 16 weeks of treatment in Study NBI-921352-DEE2012.
- Continue to use a nocturnal alerting system or practice consistent with standards of care for the duration of the study.
- Have an adequate rescue medication regimen per the investigator's judgment in place for the duration of the study.
- For Participants Who did not Participate in NBI-921352-DEE2012:
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- Written or oral pediatric assent from the participant if deemed capable of providing assent and written informed consent from the participant's parent(s) or legal guardian(s) for pediatric participants and for adult participants who are not capable of providing consent. Adult participants who are capable of providing consent should sign an ICF.
- Be a 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.
- Have a body weight of at least 10 kilograms.
Who cannot join
- For Participants Who Participated in NBI-921352-DEE2012:
- Have developed any other disorder for which the treatment takes priority over treatment of SCN8A-DEE or is likely to interfere with study treatment or impair treatment compliance.
- For Participants Who did not Participate in NBI-921352-DEE2012:
- Have symptoms that would be more consistent with another epilepsy disorder such as Dravet syndrome (for example, fever-induced episodes of status epilepticus, frequent myoclonic seizures, worsening on sodium channel blockers, absence seizures with generalized spike-and-wave electroencephalogram [EEG] as the sole seizure type).
- Currently receiving cannabinoids or medical marijuana except Epidiolex/Epidyolex, unless approved by the Sponsor.
- Currently taking systemic steroids (excluding inhaled medication for asthma treatments and intranasal steroids for allergies) such as adrenocorticotropin hormone, high-dose prednisolone for epileptic spasms. If participant has received these medications in the past, they 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 non-epilepsy-related diseases (such as allergies or dermatological conditions) are not exclusionary.
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- 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.
- Have a clinically significant medical condition or chronic disease, that in the opinion of the investigator would preclude the participant 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 participants 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 milliseconds (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, 94143
Children's National Hospital
Washington D.C., District of Columbia, 20010
About this study
Official title: A Prospective, Long-Term, Interventional, Active Extension Study to Evaluate the Safety and Tolerability of NBI-921352 as Adjunctive Therapy in Subjects With SCN8A Developmental and Epileptic Encephalopathy Syndrome (SCN8A-DEE)
Extension study to evaluate how safe and tolerable the drug NBI-921352 is when used as adjunctive therapy in participants with SCN8A developmental and epileptic encephalopathy syndrome (SCN8A-DEE).
- Being tested
- NBI-921352
- 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
| Study group | Role | What they receive |
|---|---|---|
| NBI-921352 | Experimental | NBI-921352 administered for up to 164 weeks. Receives: Drug: NBI-921352 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of Participants with Serious treatment-emergent adverse events (TEAEs), TEAEs Leading to Discontinuation and Fatal TEAEs
Measured: Day 1 to Week 168
Secondary outcomes (1)
Percentage Change from Baseline in 28-day Seizure Frequency for Countable Motor Seizures
Measured: Baseline, up to Week 162
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 Feb 2022
- Study start12 Jul 2022
- Primary completion12 Nov 2025
- Study completion12 Nov 2025
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.
- 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
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- 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
- NCT05226780
- Sponsor's protocol ID
- NBI-921352-DEE2013
- Other IDs
- 2021-004393-62
- Status last verified
- May 2026
- First submitted
- 26 Jan 2022
- Last updated
- 27 May 2026
- Results posted
- No
- 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 27 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Prospective, Long-Term, Interventional, Active Extension Study to Evaluate the Safety and Tolerability of NBI-921352 as Adjunctive Therapy in Subjects With SCN8A Developmental and Epileptic Encephalopathy Syndrome (SCN8A-DEE)
- ClinicalTrials.gov ID
- NCT05226780
- Acronym / sponsor ID
- NBI-921352-DEE2013
- 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
- 12 Jul 2022 (actual)
- Primary completion
- 12 Nov 2025 (actual)
- Study completion
- 12 Nov 2025 (actual)
- First posted
- 7 Feb 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Extension study to evaluate how safe and tolerable the drug NBI-921352 is when used as adjunctive therapy in participants with SCN8A developmental and epileptic encephalopathy syndrome (SCN8A-DEE).
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| NBI-921352 | Experimental | Drug: NBI-921352NBI-921352 administered for up to 164 weeks. |
Who may qualify
- Ages
- 2 to 22 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult
Key inclusion criteria (13 listed)
- Written or oral pediatric assent from the participant and written informed consent from the participant's parent(s) or legal guardian(s) for pediatric participants and adult participants who are not capable of providing consent. Adult participant who are ≥18 years of age and capable of providing consent should sign an Informed Consent Form (ICF).
- Completed 16 weeks of treatment in Study NBI-921352-DEE2012.
- Continue to use a nocturnal alerting system or practice consistent with standards of care for the duration of the study.
- Have an adequate rescue medication regimen per the investigator's judgment in place for the duration of the study.
- Written or oral pediatric assent from the participant if deemed capable of providing assent and written informed consent from the participant's parent(s) or legal guardian(s) for pediatric participants and for adult participants who are not capable of providing consent. Adult participants who are capable of providing consent should sign an ICF.
Key exclusion criteria (11 listed)
- Have developed any other disorder for which the treatment takes priority over treatment of SCN8A-DEE or is likely to interfere with study treatment or impair treatment compliance.
- Have symptoms that would be more consistent with another epilepsy disorder such as Dravet syndrome (for example, fever-induced episodes of status epilepticus, frequent myoclonic seizures, worsening on sodium channel blockers, absence seizures with generalized spike-and-wave electroencephalogram [EEG] as the sole seizure type).
- Currently receiving cannabinoids or medical marijuana except Epidiolex/Epidyolex, unless approved by the Sponsor.
- Currently taking systemic steroids (excluding inhaled medication for asthma treatments and intranasal steroids for allergies) such as adrenocorticotropin hormone, high-dose prednisolone for epileptic spasms. If participant has received these medications in the past, they 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 non-epilepsy-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.
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 |
Primary outcome
Number of Participants with Serious treatment-emergent adverse events (TEAEs), TEAEs Leading to Discontinuation and Fatal TEAEs
Time frame: Day 1 to Week 168
1 secondary outcome
Percentage Change from Baseline in 28-day Seizure Frequency for Countable Motor Seizures
Time frame: Baseline, up to Week 162
Results and safety
The study was stopped early (reason given: This study was prematurely terminated due to sponsor decision.). Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 27 May 2026.
- 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 13 inclusion and 11 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 27 May 2026. 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. 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?
The study was stopped early (reason given: This study was prematurely terminated due to sponsor decision.). Results are not available in the source record.
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?
Number of Participants with Serious treatment-emergent adverse events (TEAEs), TEAEs Leading to Discontinuation and Fatal TEAEs (time frame: Day 1 to Week 168). 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 27 May 2026.