Ornithine Transcarbamylase DeficiencyPhase 2NCT05526066
Study for Adolescents and Adults With Ornithine Transcarbamylase Deficiency to Evaluate Safety and Tolerability of ARCT-810
A Phase 2 study testing ARCT-810 in people with Ornithine Transcarbamylase Deficiency and OTC Deficiency, run by Arcturus Therapeutics, Inc. at 14 sites in 6 countries.
Trial summary
The primary objective is to evaluate the safety and tolerability of repeated doses of intravenously administered ARCT-810. Read more about this study
- Who is it for?
- Ages 12 to 65 years
- Conditions the study is for
- Ornithine Transcarbamylase Deficiency, OTC Deficiency, OTCD
- What is being tested?
- ARCT-810
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 8 participants
- Where
- 14 sitesin 6 countries
- Study dates
- 17 Oct 2022to 31 Oct 2024
- Phase
- Phase 2
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 12 to 65 years
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- Adequate cognitive ability to understand study requirements and give informed consent
- Males and females aged 12 to 65 years inclusive, at Screening
- Documented diagnosis of OTC deficiency
- Clinical stability (no clinical symptoms of hyperammonemia within 1 month, no hospitalizations for metabolic decompensation within 3 months, ≤ 2 hospitalizations within 1 year)
- Stable protein-restricted diet, dietary supplements, and ammonia scavenger regimen (if applicable) for at least 28 days.
- BMI = 18.0 - 32.0 kg/m2, inclusive for adults, and >5th percentile for adolescents ≥12 to 17 years
- Must be willing to adhere to contraception guidelines
Who cannot join
- History of any OTC gene therapy, or history of liver-derived stem cell therapy in the past 3 years
- 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)
- History of severe allergic reaction to liposomal or PEG-containing products
- Abuse of illicit drugs, medications or alcohol
- Clinically significant laboratory abnormalities on screening labs
Trial locations and contacts
14 sites in 6 countries.
14 sites in 6 countries
Spain4 sites
Hospital Clínic de Barcelona
Barcelona
Hospital Sant Joan de Déu
Barcelona
Hospital Universitario 12 de Octubre
Madrid, 28041
Complejo Hospitalario Universitario de Santiago (CHUS) - Hospital Clínico Universitario
Santiago de Compostela, 15706
United Kingdom4 sites
University Hospitals Birmingham NHS Foundation Trust - Queen Elizabeth Hospital Birmingham
Birmingham, UK, B15 2PR
Great Ormond Street Hospital for Children NHS Foundation Trust
London, UK, WC1N 3JH
University College London Hospitals NHS Foundation Trust - National Hospital for Neurology and Neurosurgery
London
Salford Royal NHS Foundation Trust - Salford Royal Hospital
Salford, M6 8HD
France2 sites
Hôpitaux Universitaires de Marseille - Hôpital de la Timone
Marseille, 13005
Assistance Publique - Hôpitaux de Paris (AP-HP) - Hôpital Necker-Enfants Malades
Paris
Italy2 sites
Azienda Ospedaliera di Padova
Padova, 35128
IRCCS Ospedale Pediatrico Bambino Gesu
Rome, 00165
Sweden1 site
Karolinska Universitetssjukhuset - Astrid Lindgrens Barnsjukhus
Stockholm, SE- 171 64
About this study
Official title: 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.
Read the 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.
- Conditions
- Ornithine Transcarbamylase Deficiency, OTC Deficiency, OTCD
- Being tested
- ARCT-810, Placebo
- Keywords
- OTC, OTCD, Ornithine, Transcarbamylase, mRNA, Ornithine Transcarbamylase Deficiency, OTC Deficiency
- Medical subject headings
- Ornithine Carbamoyltransferase Deficiency Disease
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ARCT-810Biological
ARCT-810 is messenger RNA (mRNA) coding for Ornithine Transcarbamylase (OTC) formulated in a lipid nanoparticle (LNP).
PlaceboOther
Normal Saline
| Study group | Role | What they receive |
|---|---|---|
| ARCT-810 | Experimental | 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. Receives: Biological: ARCT-810 |
| Placebo, Normal Saline | Placebo comparator | 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. Receives: Other: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Incidence, severity and dose-relationship of adverse events (AEs)
Safety and tolerability of ARCT-810 assessed by determining the number and severity of AEs by dose level
Measured: Week 23
Secondary outcomes (11)
Plasma concentration area under the curve after first and last doses of ARCT-810
Area under the plasma concentration versus time curve (AUC) from time zero to the last quantifiable time point
Measured: Up to 17 Weeks
Maximum observed plasma concentration (Cmax) after first and last doses of ARCT-810
The maximum observed plasma concentration (Cmax)
Measured: Up to 17 Weeks
Time at which Cmax occurred after first and last doses of ARCT-810
The time at which Cmax occurred (Tmax)
Measured: Up to 17 Weeks
AUC0-inf after first and last doses of ARCT-810
Plasma AUC from time zero extrapolated to infinity
Measured: Up to 17 Weeks
AUCExtrap after first and last doses of ARCT-810
The relative portion of AUC0-inf extrapolated beyond AUC0-t
Measured: Up to 17 Weeks
T1/2 after first and last doses of ARCT-810
Terminal half-life
Measured: Up to 17 Weeks
MRT0-inf after first and last doses of ARCT-810
The mean residence time extrapolated to infinity
Measured: Up to 17 Weeks
CL after first and last doses of ARCT-810
Total body clearance, calculated as dose divided by AUC0-inf
Measured: Up to 17 Weeks
Vss after first and last doses of ARCT-810
Volume of distribution
Measured: Up to 17 Weeks
Urea Cycle Function
Change from baseline in urea cycle function as measured by 13C-urea assay
Measured: Week 12
Plasma Ammonia
Change from baseline in urea cycle function as measured by 24-hour plasma ammonia profile
Measured: Week 11
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Sep 2022
- Study start17 Oct 2022
- Primary completion31 Oct 2024
- Study completion31 Oct 2024
Why it stopped: The study was terminated after the completion of Cohort 1 (0.3 mg/kg) due to slow enrollment in this placebo-controlled study.
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Ornithine Transcarbamylase DeficiencyStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Sequential
- Model description
- On Day 1, participants will receive a single dose of Study Drug via intravenous infusion. If the safety observations are considered acceptable, that participant will enter the multiple-dose portion of the study in which they will receive a further 5 doses of Study Drug on Days 15, 29, 43, 57 and 71.
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 8 participants (actual)
Sponsor and investigators
- Lead sponsor
- Arcturus Therapeutics, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05526066
- Sponsor's protocol ID
- ARCT-810-03
- Status last verified
- Sep 2025
- First submitted
- 8 Aug 2022
- Last updated
- 26 Sep 2025
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 26 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- 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
- ClinicalTrials.gov ID
- NCT05526066
- Acronym / sponsor ID
- ARCT-810-03
- Conditions
- Ornithine Transcarbamylase Deficiency, OTC Deficiency, OTCD
- Keywords
- OTC, OTCD, Ornithine, Transcarbamylase, mRNA, Ornithine Transcarbamylase Deficiency, OTC Deficiency
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: The study was terminated after the completion of Cohort 1 (0.3 mg/kg) due to slow enrollment in this placebo-controlled study.
- Enrolment
- 8 participants (actual)
- Lead sponsor
- Arcturus Therapeutics, Inc.Industry (pharma, biotech, devices)
- Study start
- 17 Oct 2022 (actual)
- Primary completion
- 31 Oct 2024 (actual)
- Study completion
- 31 Oct 2024 (actual)
- First posted
- 2 Sep 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The primary objective is to evaluate the safety and tolerability of repeated doses of intravenously administered ARCT-810.
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 design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Sequential
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- On Day 1, participants will receive a single dose of Study Drug via intravenous infusion. If the safety observations are considered acceptable, that participant will enter the multiple-dose portion of the study in which they will receive a further 5 doses of Study Drug on Days 15, 29, 43, 57 and 71.
| Arm | Type | Receives |
|---|---|---|
| ARCT-810 | Experimental | Biological: ARCT-810Participants 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. |
| Placebo, Normal Saline | Placebo comparator | Other: PlaceboParticipants 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. |
Who may qualify
- Ages
- 12 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (7 listed)
- Adequate cognitive ability to understand study requirements and give informed consent
- Males and females aged 12 to 65 years inclusive, at Screening
- Documented diagnosis of OTC deficiency
- Clinical stability (no clinical symptoms of hyperammonemia within 1 month, no hospitalizations for metabolic decompensation within 3 months, ≤ 2 hospitalizations within 1 year)
- Stable protein-restricted diet, dietary supplements, and ammonia scavenger regimen (if applicable) for at least 28 days.
Key exclusion criteria (5 listed)
- History of any OTC gene therapy, or history of liver-derived stem cell therapy in the past 3 years
- 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)
- History of severe allergic reaction to liposomal or PEG-containing products
- Abuse of illicit drugs, medications or alcohol
- Clinically significant laboratory abnormalities on screening labs
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| ARCT-810ARCT-810 is messenger RNA (mRNA) coding for Ornithine Transcarbamylase (OTC) formulated in a lipid nanoparticle (LNP). | Biological | ARCT-810 |
| PlaceboNormal Saline | Other | Placebo, Normal Saline |
Primary outcome
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
11 secondary outcomes
Plasma concentration area under the curve after first and last doses of ARCT-810
Time frame: Up to 17 Weeks
Maximum observed plasma concentration (Cmax) after first and last doses of ARCT-810
Time frame: Up to 17 Weeks
Time at which Cmax occurred after first and last doses of ARCT-810
Time frame: Up to 17 Weeks
AUC0-inf after first and last doses of ARCT-810
Time frame: Up to 17 Weeks
AUCExtrap after first and last doses of ARCT-810
Time frame: Up to 17 Weeks
T1/2 after first and last doses of ARCT-810
Time frame: Up to 17 Weeks
MRT0-inf after first and last doses of ARCT-810
Time frame: Up to 17 Weeks
CL after first and last doses of ARCT-810
Time frame: Up to 17 Weeks
Vss after first and last doses of ARCT-810
Time frame: Up to 17 Weeks
Urea Cycle Function
Time frame: Week 12
Plasma Ammonia
Time frame: Week 11
Results and safety
The study was stopped early (reason given: The study was terminated after the completion of Cohort 1 (0.3 mg/kg) due to slow enrollment in this placebo-controlled study.). Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 26 Sep 2025.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
14 sites in 6 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing ARCT-810 in people with Ornithine Transcarbamylase Deficiency and OTC Deficiency, run by Arcturus Therapeutics, Inc. at 14 sites in 6 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 26 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 14 sites in Spain, United Kingdom, France, Italy, Belgium and 1 more country. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study was stopped early (reason given: The study was terminated after the completion of Cohort 1 (0.3 mg/kg) due to slow enrollment in this placebo-controlled study.). Results are not available in the source record.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Incidence, severity and dose-relationship of adverse events (AEs) (time frame: Week 23). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 26 Sep 2025; AzTrials last refreshed its copy on 8 Nov 2026.