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NCT Number: NCT07773246

Phase 1/2 Study of KRRO-121 in Healthy Volunteers and Patients With UCD

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.

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Key information

Conditions

Urea Cycle Disorders, Inborn Adult-onset citrullinemia type 2 Amino Acid Metabolism, Inborn Errors Arginase 1 Deficiency Argininosuccinate Lyase Deficiency Argininosuccinate Synthase Argininosuccinic Aciduria Brain Diseases Brain Diseases, Metabolic Brain Diseases, Metabolic, Inborn Carbamylphosphate Synthetase I Central Nervous System Diseases Citrin Deficiency Congenital, Hereditary, and Neonatal Diseases and Abnormalities Genetic Diseases, Inborn Genetic Diseases, X-Linked Hyperargininemia Metabolic Diseases Metabolism, Inborn Errors N-acetyl Glutamate - Synthetase N-acetyl glutamate synthetase deficiency NAGS Deficiency Nervous System Diseases Nutritional and Metabolic Diseases Ornithine Carbamoyltransferase Deficiency Disease Ornithine Transcarbamylase (OTC) Deficiency Ornithine Transporter Mitochondrial 1 Urea Cycle Disorders

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 1 / Phase 2

Primary location

Nucleus Network Pty Ltd

Melbourne, Victoria, 3004, Australia

About this study

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

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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

Exclusion criteria

  • 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

Treatment and study plan

KRRO-121

Drug

KRRO-121, subcutaneous injection

Placebo

Drug

Placebo, subcutaneous injection

Primary outcomes

  1. Safety and Tolerability

    Time frame: Day 1 through 14 days post-dose

    Incidence of dose limiting toxicities (DLT)

  2. Safety and Tolerability

    Time frame: Day 1 through Day 50

    Frequency and severity of treatment-emergent adverse events (TEAEs; per Common Terminology Criteria for Adverse Events [CTCAE])

Secondary outcomes

  1. Pharmacokinetics (PK) of KRRO-121

    Time frame: Day 1 to Day 50

    PK profile of KRRO-121 including maximum blood concentration (Cmax)

Study contacts

Contact information is provided by the study sponsor or research team.

Nucleus Network Pty Ltd Study Director

CONTACT

[email protected]

(03) 8593 9801

Sponsors and collaborators

Lead sponsor

Korro Bio, Inc.

Industry

Registry information

Official study 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

Acronym: ANCHOR

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Aug 19, 2026
Registry last updated
Aug 19, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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