A Study of Olezarsen for the Treatment of Familial Chylomicronemia Syndrome (FCS) in Pediatric Participants

NCT07727538 | Recruiting Phase 3 DMC FDA Drug

• 1 other identifier: ISIS 678354-CS21
• Study Type: interventional
• Target: 12
• Locations: 1 country
• Sites: 3

Brief Summary

The primary purpose of the study is to evaluate the efficacy of olezarsen administered by subcutaneous injection to pediatric participants with FCS.

Conditions

Familial Chylomicronemia Syndrome

Outcome Measures

Primary Outcomes (1)

• Percent Change from Baseline in Fasting Triglycerides (TG)

  At 6 Months

Secondary Outcomes (36)

• Number of Participants with Treatment-emergent Adverse Events (TEAEs) and Serious TEAEs Including Independently Adjudicated Events of Pancreatitis, and Withdrawals due to Adverse Events (AEs)

  Up to 24 Months

• Change From Baseline in Vital Sign Parameter - Heart Rate (Beats per Minute)

  Baseline up to 24 Months

• Change From Baseline in Vital Sign Parameter - Blood Pressure (Systolic and Diastolic, mmHg)

  Baseline up to 24 Months

• Change From Baseline in Vital Sign Parameter - Oxygen Saturation (%)

  Baseline up to 24 Months

• Change From Baseline in Vital Sign Parameter - Respiratory Rate (Breaths per Minute)

  Baseline up to 24 Months

Study Arms (2)

Cohort 1

EXPERIMENTAL

Participants aged 12 to \<18 years will receive multiple doses of olezarsen, at a dose level that depends on body weight, once every month by subcutaneous injection for up to 1 year. All participants may continue to the optional 1-year long-term extension period with the last dose received being after 2 years of treatment.

Drug: Olezarsen

Cohort 2

EXPERIMENTAL

Participants aged 2 to \<12 years will receive multiple doses of olezarsen, at a dose level based on information obtained from Cohort 1, once every month by subcutaneous injection for up to 1 year. All participants may continue to the optional 1-year long-term extension period with the last dose received being after 2 years of treatment.

Drug: Olezarsen

Interventions

Olezarsen DRUG

Olezarsen will be administered by subcutaneous injection.

Also known as: ISIS 678354

Cohort 1; Cohort 2

Eligibility Criteria

• Age: 2 Years - 17 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• Parental or legally authorized representative consent must be obtained, and the participants must provide age-appropriate or cognition-appropriate assent, as determined by the Investigator. The parent or legal guardian must be able to understand and comply with the study visit schedule and all other study procedures.
• Must be able to comply with all study procedures.
• Age 12 to less than 18 years at the time of informed consent/assent (Cohort 1); age 2 to less than 12 years at time of informed consent/assent (Cohort 2).
• Willing to fast for at least 10 hours before visits requiring fasted blood sampling.
• A diagnosis of Familial Chylomicronemia Syndrome (type 1 Hyperlipoproteinemia) by documentation of confirmed homozygote, compound heterozygote or double heterozygote for loss-of-function mutations in type 1-causing genes.
• Fasting TGs ≥880 mg/dL at screening. If fasting TG is \< 880 mg/dL, up to two additional tests may be performed during the screening period with any single test used to qualify.

You may not qualify if:

• Diabetes mellitus with any of the following:
• Newly diagnosed within 12 weeks prior to screening or during the screening period.
• Hemoglobin A1c (HbA1c) ≥9.5% at screening.
• Change in basal insulin regimen \>20% within 3 months prior to screening or during the screening period.
• For participants with type 1 diabetes: episode of diabetic ketoacidosis, or ≥3 episodes of severe hypoglycemia within 6 months prior to screening or during the screening period.
• History of bleeding, diathesis, or coagulopathy.
• Major surgery within 3 months of screening.
• Plasma apheresis within 4 weeks prior to screening or planned during the study.
• Treatment with another investigational drug, biological agent, or device within one month of screening, or 5 half-lives of investigational agent, whichever is longer.
• Active pancreatitis within 4 weeks prior to screening or during the screening period.
• Malignancy diagnosed or treated within 5 years prior to screening or during the screening period.

Sponsors & Collaborators

• Ionis Pharmaceuticals, Inc.: lead

Study Sites (3)

UCSF Benioff Children's Hospital

San Francisco, California, 94143, United States

RECRUITING

University of Texas Southwestern Medical Center

Dallas, Texas, 75390, United States

RECRUITING

Cook Children's Medical Center

Fort Worth, Texas, 76104, United States

RECRUITING

MeSH Terms

Conditions

Familial hyperchylomicronemia syndrome

Interventions

olezarsen

Central Study Contacts

Ionis Pharmaceuticals, Inc.

CONTACT

(844) 200-6410; IonisOlezarsenPediatric@clinicaltrialmedia.com

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 10, 2026
• First Posted: July 27, 2026
• Study Start: July 1, 2026
• Primary Completion (Estimated): August 1, 2030
• Study Completion (Estimated): August 1, 2031
• Last Updated: July 29, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will share

Locations

US (3)