CS-121 APOC3 Base Editing in Children and Adolescents With Hyperchylomicronemia

January 19, 2026 updated by: Xiumin Wang, PhD, Shanghai Jiao Tong University School of Medicine

A Prospective, Single-center, Open-label, Single-arm Clinical Study to Evaluate the Safety and Efficacy of CS-121, an In Vivo Base Editing Therapy Delivered by Lipid Nanoparticles Targeting APOC3, in Children and Adolescents With Hyperchylomicronemia

This is a Prospective, Single-center, Open-label, Single-arm Clinical Study to Evaluate the Safety and Efficacy of CS-121, an In Vivo Base Editing Therapy Delivered by Lipid Nanoparticles Targeting APOC3, in Children and Adolescents (4-18 years) With Hyperchylomicronemia

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

CS-121 is an investigational, in vivo base editing therapy delivered by lipid nanoparticles (LNPs) targeting the APOC3 gene in the liver. By introducing precise base edits at specific APOC3 loci, CS-121 is intended to mimic naturally occurring protective mutations that reduce APOC3 expression, thereby restoring triglyceride clearance pathways and lowering pancreatitis risk. Preclinical studies in transgenic mouse and non-human primate models demonstrated dose-dependent APOC3 editing, reductions in serum ApoC3 protein and triglyceride levels, and acceptable safety profiles, supporting advancement into human evaluation. This open-label, single-arm, dose-escalation early exploratory trial designed to evaluate the safety, tolerability, PK/PD characteristics and preliminary efficacy of CS-121 in patients with hyperchylomicronemia. Based on the properties of gene editing therapy, the primary focus of the study is to identify the optimal biological dose (OBD) rather than the traditional maximum tolerated dose (MTD).

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
15

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Early Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • China
    • Shanghai Municipality
      • Shanghai, Shanghai Municipality, China
        • Recruiting
        • Shanghai Children's Medical Center
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Child
  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Male or female participants aged 4 years ≤ age < 18 years.
  • Severe hypertriglyceridemia (sHTG), defined as a triglyceride (TG) level ≥ 500 mg/dL.
  • Confirmed diagnosis of genetically inherited FCS via genetic testing, or clinically diagnosed FCS plus persistent chylomicronemia.
  • Failure to achieve adequate TG control, For participants under 8 years of age, the investigator determine at their discretion whether prior lipidlowering therapy has been administered.
  • Participants aged 6 years and above must sign the informed consent form themselves; for participants under 18 years of age, their parent/legal guardian must sign the informed consent form. (Participants under 6 years of age are exempt from signing the written informed consent form).
  • Female participants of childbearing potential must have a negative result on serum pregnancy testing.

Exclusion Criteria:

  • Currently participating in other interventional clinical studies, or having an insufficient washout period of less than 5 half-lives or 30 days (whichever is longer) since the last administration of other investigational drugs.
  • Used antisense oligonucleotide (ASO)-based or small interfering RNA (siRNA)-based lipid-lowering drugs targeting APOC3 within 3 months prior to study drug administration.
  • History of acute pancreatitis within 1 month before dosing.
  • Patients who underwent major surgery within 3 months prior to study drug administration and are judged by the investigator as unsuitable for receiving the study drug, due to potential intolerance to adverse events such as cytokine release storm.
  • ALT or AST ≥2 × ULN
  • Total bilirubin ≥1.5 × ULN
  • eGFR <30 mL/min/1.73 m²
  • Random urine albumin-to-creatinine ratio (UACR) >30 mg/g, or urine protein is ≥ 2+
  • HbA1c ≥9%
  • Coagulation function abnormalities judged by the investigator as unsuitable for CS-121 administration.
  • Positive results for HBsAg, dual positivity for HCV antibody and RNA, positive for HIV, or positive for Treponema pallidum infection.
  • Known major organ diseases, mental disorders, Cushing's syndrome, hypothyroidism, history of lymphoproliferative disorders, or malignant tumors in any organ system, which are judged by the investigator as unsuitable for study participation due to potential intolerance to adverse events such as cytokine Release-Storm.
  • Concomitant medications/treatments judged by the investigator to affect lipid metabolism, liver and kidney function, coagulation function, or interfere with the efficacy evaluation of the study drug.
  • Patients of childbearing potential who are planning pregnancy, breastfeeding, or have fertility plans.
  • History of hypersensitivity to any study drug, its excipients, or drugs of similar chemical classes.
  • Other medical conditions or comorbidities that, in the investigator's opinion, may interfere with study compliance or data interpretation.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Low Dose CS-121
Participants in this arm will receive low dose of CS-121
Biological: CS-121
CS-121 is a in vivo base editing therapy formulated in lipid nanoparticles for targeted editing of the APOC3 gene in hepatocytes.
Experimental: Middle Dose CS-121
Participants in this arm will receive middle dose of CS-121
Biological: CS-121
CS-121 is a in vivo base editing therapy formulated in lipid nanoparticles for targeted editing of the APOC3 gene in hepatocytes.
Experimental: High Dose CS-121
Participants in this arm will receive high dose of CS-121
Biological: CS-121
CS-121 is a in vivo base editing therapy formulated in lipid nanoparticles for targeted editing of the APOC3 gene in hepatocytes.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
Dose-limiting toxicities (DLTs)
Time Frame: Within 14 days post CS-121 dosing
Within 14 days post CS-121 dosing
The incidence and severity of treatment-emergent adverse events (TEAEs)
Time Frame: from screening to 10 months post last dosing
from screening to 10 months post last dosing

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Time Frame
Changes in serum triglyceride (TG) levels
Time Frame: From baseline to 10 months post last dosing
From baseline to 10 months post last dosing
Changes in serum ApoC3 levels from baseline
Time Frame: From baseline to 10 months post last dosing
From baseline to 10 months post last dosing
Concentrations of the active components of CS-121 (sgRNA and mRNA)
Time Frame: From baseline to 1 month post last dosing
From baseline to 1 month post last dosing

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Shanghai Jiao Tong University School of Medicine

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
CorrectSequence Therapeutics Co., Ltd

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 26, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
October 31, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 31, 2041

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 19, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 19, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 28, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
January 28, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 19, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • CS-121-02

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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