Study to Evaluate NBI-921352 as Adjunctive Therapy in Subjects With SCN8A Developmental and Epileptic Encephalopathy Syndrome (SCN8A-DEE)

NCT04873869 | Terminated Phase 2 Results DMC FDA Drug

• 2 other identifiers: NBI-921352-DEE20122020-003140-83
• Study Type: interventional
• Target: 8
• Locations: 1 country
• Sites: 4

Brief 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).

Conditions

SCN8A Developmental and Epileptic Encephalopathy Syndrome

Keywords

Epilepsy; Sodium channel; voltage-gated; type VIII; alpha subunit (SCN8A); NaV1.6 inhibitor

Outcome Measures

Primary Outcomes (1)

• Percentage Change From Baseline in 28-day Seizure Frequency for Countable Motor Seizures During the 16-week Treatment Period

  Planned time frame: Baseline to Week 16

Secondary Outcomes (8)

• Percentage of Participants With a Treatment Response

  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

  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

  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

  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

  Planned time frame: Up to Week 16

Study Arms (2)

Placebo

PLACEBO COMPARATOR

Participants will receive matching placebo for up to 18 weeks.

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).

Drug: NBI-921352

Interventions

NBI-921352 DRUG

Administered orally

NBI-921352

Placebo DRUG

Administered orally

Placebo

Eligibility Criteria

• Age: 2 Years - 21 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• 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
• 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

You may not qualify if:

• 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
• 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 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.

Sponsors & Collaborators

• Neurocrine Biosciences: lead

Study Sites (4)

UCSF Medical Center

San Francisco, California, 94158, United States

Location

Children's National Hospital

Washington D.C., District of Columbia, 20010, United States

Location

University of Rochester

Rochester, New York, 14642, United States

Location

Cook Children's Medical Center

Fort Worth, Texas, 76104, United States

Location

MeSH Terms

Conditions

Epilepsy

Condition Hierarchy (Ancestors)

Brain Diseases; Central Nervous System Diseases; Nervous System Diseases

Limitations and Caveats

Due to the early termination, only 8 participants were enrolled and completed the study.

Results Point of Contact

• Title: Neurocrine Medical Information
• Organization: Neurocrine Biosciences

medinfo@neurocrine.com

+1 877-641-3461

Study Officials

• Clinical Development Lead

  Neurocrine Biosciences

  STUDY DIRECTOR

Publication Agreements

• PI is Sponsor Employee: No
• Restrictive Agreement: Yes

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: April 30, 2021
• First Posted: May 5, 2021
• Study Start: January 31, 2022
• Primary Completion: March 17, 2023
• Study Completion: March 17, 2023
• Last Updated: October 16, 2025
• Results First Posted: October 16, 2025

Record last verified: 2025-09

Data Sharing

• IPD Sharing: Will not share

Locations

US (4)