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KRRO-121

Phase 1

Urea Cycle Disorders, Inborn | Small molecule | Rare Disease |Korro Bio, Inc.|Last Updated: Aug 20, 2026

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLED
Total Trials1
Total Enrollment30

FDA Designations

No designations recorded

Clinical trial landscape

KRRO-121 · 1 trial · 11 indications

Phase 1 1
NCT07773246Phase 1/2 Study of KRRO-121 in Healthy Volunteers and Patients With UCDUrea Cycle Disorders, Inborn
NOT YET_RECRUITING30 Analytics
PHASE1NOT YET_RECRUITING
Phase 1/2 Study of KRRO-121 in Healthy Volunteers and Patients With UCD
Urea Cycle Disorders, InbornUnlock trial analytics

Study Endpoints

Primary Endpoints

Incidence of dose limiting toxicities (DLT) (Safety and Tolerability)
Day 1 through 14 days post-dose

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.

Frequency and severity of treatment-emergent adverse events (TEAEs; per Common Terminology Criteria for Adverse Events [CTCAE]) (Safety and Tolerability)
Day 1 through Day 50

Any adverse event (AE) per Common Terminology Criteria for Adverse Events (CTCAE),

Secondary Endpoints

Maximum blood concentration (Cmax)
Day 1 to Day 50
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Study Design & Arms

AllocationRANDOMIZED
MaskingTRIPLE
ModelSEQUENTIAL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
KRRO-121EXPERIMENTALKRRO-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.
PlaceboPLACEBO_COMPARATORPlacebo

Interventions

NameTypeDescription
KRRO-121DRUGKRRO-121, subcutaneous injection
PlaceboDRUGPlacebo, subcutaneous injection
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Eligibility Criteria

Age Range18 Years to 65 Years
SexALL
Healthy VolunteersYes
Study Sites1

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 childbeari...

Countries:Australia
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Recent Changes (Last 90 Days)

LOWAug 20, 2026NCT07773246NEW_TRIAL: changed
LOWAug 20, 2026NCT07773246NEW_TRIAL: changed
LOWAug 20, 2026NCT07773246NEW_TRIAL: changed
LOWAug 20, 2026NCT07773246NEW_TRIAL: changed

Frequently asked questions about KRRO-121

What is KRRO-121 used for?

KRRO-121 is an investigational small molecule being developed for the treatment of inborn urea cycle disorders, a group of rare genetic conditions that impair the body's ability to remove ammonia from the blood. It is being studied in patients with various urea cycle disorders, including ornithine transcarbamylase deficiency, arginase 1 deficiency, and citrin deficiency.

What does KRRO-121 target?

KRRO-121 is a small molecule designed to address inborn urea cycle disorders, which involve deficiencies in enzymes or transporters of the urea cycle. The specific molecular target of KRRO-121 has not been disclosed in the available information.

Who makes KRRO-121?

KRRO-121 is being developed by Korro Bio, Inc., a biopharmaceutical company listed on the stock exchange under the ticker symbol KRRO. The company is conducting clinical research on this investigational therapy for urea cycle disorders.

What phase is KRRO-121 in?

KRRO-121 is in Phase 1 clinical development. A Phase 1/2 study is planned to evaluate the drug in healthy volunteers and patients with urea cycle disorders, but the trial has not yet started recruiting participants.

What clinical trials is KRRO-121 in?

KRRO-121 is being studied in a Phase 1/2 clinical trial with the identifier NCT07773246. This randomized, double-blind, placebo-controlled study plans to enroll 30 participants in Australia, including healthy volunteers and patients with urea cycle disorders.

Is KRRO-121 the same as any other drug?

KRRO-121 is the primary name for this investigational drug. No alternative names have been reported for this asset in the available information.