Urea Cycle Disorders, InbornPhase 1/2ANCHORNCT07773246
Phase 1/2 Study of KRRO-121 in Healthy Volunteers and Patients With UCD
A Phase 1/2 study testing KRRO-121 in people with Urea Cycle Disorders, Inborn and Urea Cycle Disorders, run by Korro Bio, Inc. at 1 site in Australia.
Trial summary
Phase 1/2 Study of KRRO-121 is a randomized, placebo-controlled study in Healthy Volunteers (Phase 1 SAD and MAD) and Study Participants with Urea Cycle Disorders (Phase 2). The primary objective of the study is to evaluate the safety of KRRO-121. Read more about this study
- Who is it for?
- Ages 18 to 65 yearsHealthy volunteers can take part
- Conditions the study is for
- Urea Cycle Disorders, Inborn, Urea Cycle Disorders, Ornithine Transcarbamylase (OTC) Deficiency
- What is being tested?
- KRRO-121
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 30 participants
- Where
- 1 siteAustralia
- Study dates
- 28 Sep 2026to Sep 2027
- Phase
- Phase 1/2
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 18 to 65 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Adult male or female participants, 18 to 65 years of age
- Healthy as determined by medical history, physical examination, vital signs, 12-lead electrocardiogram (ECG), and screening laboratory assessments, in the opinion of the Investigator.
- Female participant of childbearing potential or male participant that is willing to use an approved, reliable means of contraception
- Willing and able to provide signed written informed consent and to comply with all study requirements
Who cannot join
- Any medical history that is clinically significant in the opinion of the Principal Investigator and Sponsor Medical Monitor
- Any laboratory value at screening or predose on Day -1 outside the local laboratory reference range that is clinically significant in the opinion of the Principal Investigator and Sponsor Medical Monitor
- Evidence of active systemic infection at Screening or Day 1 requiring antimicrobial, antiviral, or antifungal therapy
- Use of any investigational drug or device within 3 months or 5 half-lives (whichever is longer) prior to Day 1
- Concurrent participation in any other interventional clinical study
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Australia1 site, 1 recruiting
- Recruiting
Nucleus Network Pty Ltd
Melbourne, Victoria, 3004
Study Director Medical Director, KRRO-121-001_General@korrobio.com
About this study
Official title: A Phase 1/2, Randomized, Double-Blind, Placebo-Controlled, Single- and Multiple-Ascending Dose Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of KRRO-121 in Healthy Volunteers and Patients With Urea Cycle Disorders
Phase 1/2 Study of KRRO-121 is a randomized, placebo-controlled study in Healthy Volunteers (Phase 1 SAD and MAD) and Study Participants with Urea Cycle Disorders (Phase 2). The primary objective of the study is to evaluate the safety of KRRO-121.
Read the detailed description
KRRO-121 is a GalNAc-conjugated RNA editing oligonucleotide in development for the potential treatment of hyperammonemia in patients with UCDs. Utilizing Korro's proprietary OPERA® platform, KRRO-121 is designed to generate a stabilized, de novo glutamine synthetase (GS) protein, a critical enzyme involved in ammonia clearance. This synthetic rescue approach is designed to augment ammonia clearance in hyperammonemia-driven diseases such as UCDs. Korro's preclinical data support the potential for KRRO-121 to be a UCD treatment that may control ammonia levels independent of any mutational background (pan-UCD).
The purpose of this first-in-human (FIH) study is to determine the safety and tolerability of escalating doses of KRRO-121, to evaluate the pharmacokinetics of KRRO-121, and to assess the effect of KRRO-121 in healthy volunteers and in study participants with UCD. The study name is ANCHOR: AssessmeNt of Control of Hyperammonemia through Oligonucleotide-based RNA editing
- Conditions
- Urea Cycle Disorders, Inborn, Urea Cycle Disorders, Ornithine Transcarbamylase (OTC) Deficiency, Arginase 1 Deficiency, NAGS Deficiency, Carbamylphosphate Synthetase I
- Being tested
- KRRO-121, Placebo
- Keywords
- KRRO-121, stabilized variant of glutamine synthetase (GS), ammonia clearance, RNA-editing
- Medical subject headings
- Urea Cycle Disorders, Inborn, Ornithine Carbamoyltransferase Deficiency Disease, Hyperargininemia, N-acetyl glutamate synthetase deficiency, Argininosuccinic Aciduria, Adult-onset citrullinemia type 2
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
KRRO-121Drug
KRRO-121, subcutaneous injection
PlaceboDrug
Placebo, subcutaneous injection
| Study group | Role | What they receive |
|---|---|---|
| KRRO-121 | Experimental | KRRO-121 is a GalNAc-conjugated RNA-editing oligonucleotide that recruits endogenous hepatic ADAR to edit mRNA, producing a de novo glutamine synthetase (GS) protein resistant to feedback-driven proteasomal degradation. By stabilizing hepatic GS, KRRO-121 augments ammonia clearance capacity independently of the underlying urea cycle enzyme defect. Receives: Drug: KRRO-121 |
| Placebo | Placebo comparator | Placebo Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Incidence of dose limiting toxicities (DLT) (Safety and Tolerability)
General toxicity: Any Grade 3 or higher adverse event (AE) per Common Terminology Criteria for Adverse Events (CTCAE); Serious adverse events: Any serious adverse event (SAE) assessed as related or possibly related to KRRO-121.
Measured: Day 1 through 14 days post-dose
Frequency and severity of treatment-emergent adverse events (TEAEs; per Common Terminology Criteria for Adverse Events [CTCAE]) (Safety and Tolerability)
Any adverse event (AE) per Common Terminology Criteria for Adverse Events (CTCAE),
Measured: Day 1 through Day 50
Secondary outcomes (1)
Maximum blood concentration (Cmax)
Maximum blood concentration (Cmax) of KRRO-121
Measured: Day 1 to Day 50
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Aug 2026
- Study start28 Sep 2026
- Primary completionAug 2027 (estimated)
- Study completionSep 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Urea Cycle Disorders, InbornStudies 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 1/2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Sequential
- Model description
- Placebo-controlled dose escalation
- Masking
- Triple blind
- Who is masked
- Participant, Care provider, Investigator
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Korro Bio, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07773246
- Sponsor's protocol ID
- KRRO-121-001
- Acronym
- ANCHOR
- Status last verified
- Oct 2026
- First submitted
- 14 Aug 2026
- Last updated
- 8 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided