Study for Adolescents and Adults With Ornithine Transcarbamylase Deficiency to Evaluate Safety and Tolerability of ARCT-810

September 22, 2025 updated by: Arcturus Therapeutics, Inc.

Phase 2, Randomized, Double-Blind, Placebo-Controlled, Nested Single and Multiple Ascending Dose Study to Evaluate the Safety, Tolerability and Pharmacokinetics of ARCT-810 in Adolescent and Adult Participants With Ornithine Transcarbamylase Deficiency

The primary objective is to evaluate the safety and tolerability of repeated doses of intravenously administered ARCT-810.

Study Overview

Status

Status

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

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

This study is a Phase 2, randomized, placebo-controlled study of ARCT-810 in people living with OTC deficiency 12 years of age and older. After an at least 4 week screening and diet stabilization period, participants will be randomized 3:1 to receive ARCT-810 or placebo. Following the first dose and safety evaluation, participants will receive up to an additional 5 doses of ARCT-810 or placebo, each separated by 14 days. The treatment period is followed by a 12-week observation period.

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 (Actual)

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.
8

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.
  • Phase 2

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 Contact Backup

Study Locations

  • Belgium
      • Brussels, Belgium, 1200
        • Cliniques Universitaires Saint Luc
  • France
      • Marseille, France, 13005
        • Hôpitaux Universitaires de Marseille - Hôpital de la Timone
      • Paris, France
        • Assistance Publique - Hôpitaux de Paris (AP-HP) - Hôpital Necker-Enfants Malades
  • Italy
      • Padua, Italy, 35128
        • Azienda Ospedaliera di Padova
      • Rome, Italy, 00165
        • Irccs Ospedale Pediatrico Bambino Gesu
  • Spain
      • Barcelona, Spain
        • Hospital Clinic de Barcelona
      • Barcelona, Spain
        • Hospital Sant Joan de Déu
      • Madrid, Spain, 28041
        • Hospital Universitario 12 de Octubre
      • Santiago de Compostela, Spain, 15706
        • Complejo Hospitalario Universitario de Santiago (CHUS) - Hospital Clínico Universitario
  • Sweden
      • Stockholm, Sweden, SE- 171 64
        • Karolinska Universitetssjukhuset - Astrid Lindgrens Barnsjukhus
  • United Kingdom
      • London, United Kingdom
        • University College London Hospitals NHS Foundation Trust - National Hospital for Neurology and Neurosurgery
      • Salford, United Kingdom, M6 8HD
        • Salford Royal NHS Foundation Trust - Salford Royal Hospital
    • UK
      • Birmingham, UK, United Kingdom, B15 2PR
        • University Hospitals Birmingham NHS Foundation Trust - Queen Elizabeth Hospital Birmingham
      • London, UK, United Kingdom, WC1N 3JH
        • Great Ormond Street Hospital for Children NHS Foundation Trust

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

12 years to 65 years (Child, Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Key Inclusion Criteria:

  1. Adequate cognitive ability to understand study requirements and give informed consent
  2. Males and females aged 12 to 65 years inclusive, at Screening
  3. Documented diagnosis of OTC deficiency
  4. Clinical stability (no clinical symptoms of hyperammonemia within 1 month, no hospitalizations for metabolic decompensation within 3 months, ≤ 2 hospitalizations within 1 year)
  5. Stable protein-restricted diet, dietary supplements, and ammonia scavenger regimen (if applicable) for at least 28 days.
  6. BMI = 18.0 - 32.0 kg/m2, inclusive for adults, and >5th percentile for adolescents ≥12 to 17 years
  7. Must be willing to adhere to contraception guidelines

Key Exclusion Criteria:

  1. History of any OTC gene therapy, or history of liver-derived stem cell therapy in the past 3 years
  2. History of other medical conditions that may make the participant unsuitable for inclusion or could interfere with study participation (e.g., uncontrolled hypertension or diabetes, malignancy, HIV, hepatitis B or C)
  3. History of severe allergic reaction to liposomal or PEG-containing products
  4. Abuse of illicit drugs, medications or alcohol
  5. Clinically significant laboratory abnormalities on screening labs

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: Randomized
  • Interventional Model: Sequential Assignment
  • Masking: Quadruple

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: ARCT-810
Participants receive an initial intravenous (IV) infusion ARCT-810. If considered safe and well tolerated, participants will receive up to 5 additional IV infusions of ARCT-810 administered at 14-day intervals.
Biological: ARCT-810
ARCT-810 is messenger RNA (mRNA) coding for Ornithine Transcarbamylase (OTC) formulated in a lipid nanoparticle (LNP).
Placebo Comparator: Placebo, Normal Saline
Participants receive an initial IV infusion of placebo. If considered safe and well tolerated, participants receive up to 5 additional IV infusions of placebo administered at 14-day intervals.
Other: Placebo
Normal Saline

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
Measure Description
Time Frame
Incidence, severity and dose-relationship of adverse events (AEs)
Time Frame: Week 23
Safety and tolerability of ARCT-810 assessed by determining the number and severity of AEs by dose level
Week 23

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
Measure Description
Time Frame
Plasma concentration area under the curve after first and last doses of ARCT-810
Time Frame: Up to 17 Weeks
Area under the plasma concentration versus time curve (AUC) from time zero to the last quantifiable time point
Up to 17 Weeks
Maximum observed plasma concentration (Cmax) after first and last doses of ARCT-810
Time Frame: Up to 17 Weeks
The maximum observed plasma concentration (Cmax)
Up to 17 Weeks
Time at which Cmax occurred after first and last doses of ARCT-810
Time Frame: Up to 17 Weeks
The time at which Cmax occurred (Tmax)
Up to 17 Weeks
AUC0-inf after first and last doses of ARCT-810
Time Frame: Up to 17 Weeks
Plasma AUC from time zero extrapolated to infinity
Up to 17 Weeks
AUCExtrap after first and last doses of ARCT-810
Time Frame: Up to 17 Weeks
The relative portion of AUC0-inf extrapolated beyond AUC0-t
Up to 17 Weeks
T1/2 after first and last doses of ARCT-810
Time Frame: Up to 17 Weeks
Terminal half-life
Up to 17 Weeks
MRT0-inf after first and last doses of ARCT-810
Time Frame: Up to 17 Weeks
The mean residence time extrapolated to infinity
Up to 17 Weeks
CL after first and last doses of ARCT-810
Time Frame: Up to 17 Weeks
Total body clearance, calculated as dose divided by AUC0-inf
Up to 17 Weeks
Vss after first and last doses of ARCT-810
Time Frame: Up to 17 Weeks
Volume of distribution
Up to 17 Weeks
Urea Cycle Function
Time Frame: Week 12
Change from baseline in urea cycle function as measured by 13C-urea assay
Week 12
Plasma Ammonia
Time Frame: Week 11
Change from baseline in urea cycle function as measured by 24-hour plasma ammonia profile
Week 11

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.
Arcturus Therapeutics, Inc.

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 (Actual)

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.
October 17, 2022

Primary Completion (Actual)

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, 2024

Study Completion (Actual)

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.
October 31, 2024

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).
August 8, 2022

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.
August 30, 2022

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.
September 2, 2022

Study Record Updates

Last Update Posted (Estimated)

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.
September 26, 2025

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.
September 22, 2025

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.
September 1, 2025

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.
  • ARCT-810-03

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

product manufactured in and exported from the U.S.

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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