Extension Study to Evaluate NBI-827104 in Pediatric Participants With Epileptic Encephalopathy With Continuous Spike-and-Wave During Sleep (Steamboat 2)

Long-Term, Open-Label Extension Study to Evaluate the Safety and Tolerability of NBI-827104 in Pediatric Subjects With Epileptic Encephalopathy With Continuous Spike-and-Wave During Sleep

The primary objective for this study is to evaluate the long-term safety and tolerability of NBI-827104 in pediatric participants with epileptic encephalopathy with continuous spike-and-wave during sleep (EECSWS).

Study Overview

• Status: Terminated
• Conditions: Epileptic Encephalopathy; Continuous Spike and Wave During Sleep
• Intervention / Treatment: Drug: NBI-827104

Detailed Description

This study will enroll participants who completed treatment in the Phase 2, multicenter, randomized, double-blind, placebo-controlled, parallel-group Study NBI-827104-CSWS2010 (NCT04625101). Participants who did not participate in Study NBI-827104-CSWS2010 may also be eligible for enrollment.

• Study Type: Interventional
• Enrollment (Actual): 19
• Phase: Phase 2

Contacts and Locations

Study Locations

• Denmark
  • Dianalund, Denmark, 4293
    • Neurocrine Clinical Site
• Spain
  • Barcelona, Spain, 08950
    • Neurocrine Clinical Site
  • Madrid, Spain, 28034
    • Neurocrine Clinical Site
• Switzerland
  • Zurich, Switzerland, 8032
    • Neurocrine Clinical Site
• United Kingdom
  • London, United Kingdom, WC1N 3JH
    • Neurocrine Clinical Site
• United States
  • California
    • Orange, California, United States, 92868
      • Neurocrine Clinical Site
  • Colorado
    • Aurora, Colorado, United States, 80045
      • Neurocrine Clinical Site
  • District of Columbia
    • Washington D.C., District of Columbia, United States, 20010
      • Neurocrine Clinical Site
  • Florida
    • Miami, Florida, United States, 33155
      • Neurocrine Clinical Site
  • Minnesota
    • Rochester, Minnesota, United States, 55905
      • Neurocrine Clinical Site
  • North Carolina
    • Durham, North Carolina, United States, 27705
      • Neurocrine Clinical Site
  • Ohio
    • Cleveland, Ohio, United States, 44195
      • Neurocrine Clinical Site

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 4 years and older (Child)
• Accepts Healthy Volunteers: No

Description

Key Inclusion Criteria:

For participants who enroll directly following the completion of the Study NBI-827104-CSWS2010:

• Completed 12 weeks of treatment in Study NBI-827104-CSWS2010.

For Participants Who Do Not Enroll Directly from or Did Not Participate in Study NBI-827104-CSWS2010:

• Have diagnosis of EECSWS confirmed by the Diagnosis Confirmation Panel (DCP).

Key Exclusion Criteria:

For participants who enroll directly following the completion of the Study NBI-827104-CSWS2010:

• Have developed any other disorder for which the treatment takes priority over treatment of EECSWS or is likely to interfere with study treatment or impair treatment compliance.

For Participants Who Do Not Enroll Directly from or Did Not Participate in Study NBI-827104-CSWS2010:

• Body weight <15 kg at Day 1.
• Clinically relevant findings related to cardiovascular or laboratory parameters at screening as determined by the investigator.
• Presence of relevant neurological disorders other than EECSWS and its underlying conditions as judged by the investigator. Symptomatic conditions underlying EECSWS (for example, neonatal strokes) have to be stable for at least 1 year prior to screening.
• Planned surgical intervention related to structural abnormalities of the brain from screening through the Week 6 Visit.
• Used any active investigational drug other than NBI-827104 in the context of a clinical study within 30 days or 5 half-lives (whichever is longer) before screening or plans to use such an investigational drug (other than NBI-827104) during the study.
• Have developed any other disorder for which the treatment takes priority over treatment of EECSWS or is likely to interfere with study treatment or impair treatment compliance.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: NBI-827104; NBI-827104 administered orally	Drug: NBI-827104; T-type calcium channel blocker.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The Number of Participants With Serious Treatment-emergent Adverse Events (TEAEs)	A TEAE is an adverse event (AE) that was not present prior to the initiation of study treatment or was an already present condition that worsened either in intensity or frequency following the initiation of study treatment.	Up to 884 days of treatment and 4-week safety follow-up (mean duration of exposure was 649.7 days)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Ratio of Spike-Wave Index during the first hour of nonrapid eye movement sleep based on centralized video-EEG reading.		Baseline and Week 26
Change from baseline in Clinical Global Impression of Severity score	The Clinical Global Impression of Severity rates overall symptom severity on a 7-point scale ranging from 1 (normal, not at all ill) to 7 (among the most extremely ill patients), as assessed by the investigator.	Baseline and Week 26
Clinical Global Impression of Change score	The Clinical Global Impression of Change is a 7-point scale that rates the overall global improvement since the initiation of study drug dosing, ranging from 1 (very much improved) to 7 (very much worse), as assessed by the clinician.	Week 26
Caregiver Global Impression of Change score	The Caregiver Global Impression of Change is a 7-point scale that rates the overall global improvement since the initiation of study drug dosing, ranging from 1 (very much improved) to 7 (very much worse), as assessed by the caregiver.	Week 26

Collaborators and Investigators

• Sponsor: Neurocrine Biosciences
• Investigators: Study Director: Clinical Development Lead, Neurocrine Biosciences

Study record dates

Study Major Dates

• Study Start (Actual): June 7, 2022
• Primary Completion (Actual): January 27, 2025
• Study Completion (Actual): January 27, 2025

Study Registration Dates

• First Submitted: March 21, 2022
• First Submitted That Met QC Criteria: March 21, 2022
• First Posted (Actual): March 31, 2022

Study Record Updates

• Last Update Posted (Actual): February 13, 2026
• Last Update Submitted That Met QC Criteria: January 27, 2026
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: Epilepsy; Epileptic Encephalopathy; Neurocrine; NBI-827104; Steamboat 2
• Additional Relevant MeSH Terms: Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Epilepsy
• Other Study ID Numbers: NBI-827104-CSWS2025; 2021-006788-11 (EudraCT Number)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No