A Phase 1/2a, Single- and Multiple-dose Escalation Study of KRRO-110 (REWRITE)

April 14, 2026 updated by: Korro Bio, Inc.

A Phase 1/2a, Single- and Multiple-dose Escalation Study to Evaluate the Safety, Tolerability, Pharmacodynamics, and Pharmacokinetics of KRRO 110 in Healthy Adult Volunteers and in Adult Participants With Alpha-1 Antitrypsin Deficiency (AATD) (REWRITE)

The purpose of this first-in human (FIH) study is to assess the safety, tolerability, and pharmacokinetics (PK) of single and multiple doses of KRRO-110 in both healthy adult participants and in clinically stable patients with Alpha-1 antitrypsin deficiency (AATD).

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.

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.
42

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
  • Phase 1

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 Locations

  • Australia
    • Queensland
      • Brisbane, Queensland, Australia, 4032
        • The Prince Charles Hospital
    • Victoria
      • Melbourne, Victoria, Australia, 3065
        • St. Vincent's Hospital Melbourne
      • Melbourne, Victoria, Australia, 3004
        • Nucleus Network Pty Ltd
  • New Zealand
      • Auckland, New Zealand
        • New Zealand Clinical Research
      • Christchurch, New Zealand
        • New Zealand Clinical Research

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

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

Part A SAD cohort Inclusion Criteria (Healthy Volunteers)

  • Adult male or female participants, 18 to 65 years of age
  • Documented PiMM genotype
  • Participants who are willing to and able to provide signed written informed consent

PiZZ Genotype (Part A SAD and Part B MAD cohorts) Inclusion Criteria (PiZZ Genotype)

  • Adult male or female participants 18 to 70 years of age (inclusive)
  • Documented PiZZ genotype
  • Baseline blood total AAT level < 11 µM/L

Exclusion Criteria:

Exclusion Criteria (Healthy Volunteers)

  • Female participant of childbearing potential or male participant that is unable or unwilling to use an approved, reliable means of contraception
  • Body mass index (BMI) > 32 or < 18.5 kg/m2
  • History or current clinical evidence of hepatic disease
  • Evidence of active infection
  • History of medical condition(s), eg, advance cardiac disease, current or recent malignancy, organ transplantation, or other illness
  • Serology result indicative of any exposure (past or active) to hepatitis C, hepatitis B, or human immunodeficiency virus (HIV)
  • Respiratory or other acute illness within 8 weeks
  • Tobacco use of any kind within 6 months

Exclusion Criteria (PiZZ Genotype)

  • Female participant of childbearing potential or male participant that is unable or unwilling to use an approved, reliable means of contraception
  • BMI > 32 or < 18.5 kg/m2 or weight > 90 kg
  • History of FEV1 < 35%
  • History or current clinical evidence of advanced hepatic disease and/or pulmonary disease
  • Use of an experimental therapy except KRRO-110 within 6 months or 5 half-lives for the experimental therapy, whichever is greater
  • Tobacco use of any kind within 6 months
  • Use of conventionally dosed AAT augmentation therapy within 5 half-lives
  • Serology result consistent with exposure to HIV, or serology consistent with active hepatitis B or hepatitis C infection

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: Double

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: Arm 1: KRRO-110 (Part A and Part B)
KRRO-110 is an RNA editing oligonucleotide encapsulated in a lipid nanoparticle (LNP) administered by intravenous (IV) infusion as a single dose in Part A (SAD), multi-dose in Part B (MAD).
Drug: KRRO-110
KRRO-110 drug product, IV
Placebo Comparator: Arm 2: Placebo (Part A only)
Placebo, IV administration
Drug: KRRO-110
KRRO-110 drug product, IV

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
Safety and Tolerability
Time Frame: From Day 1 to Day 43 in the SAD and from Day 1 to Day 85 in the MAD
Type, frequency, and severity of treatment-emergent adverse events (TEAEs)
From Day 1 to Day 43 in the SAD and from Day 1 to Day 85 in the MAD

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
Pharmacokinetics (PK) of KRRO-110
Time Frame: Day 1 to Day 43 (SAD), and Day 1 to Day 85 (MAD)
PK profile of KRRO-110 including maximum blood concentration (Cmax)
Day 1 to Day 43 (SAD), and Day 1 to Day 85 (MAD)
Pharmacodynamics (PD) of KRRO-110
Time Frame: Day 1 to Day 43 (SAD), and Day 1 to Day 85 (MAD)
PD profile of KRRO-110 based on change from Baseline in alpha-antitrypsin (AAT) enzyme levels at all measured timepoints (PiZZ participants only).
Day 1 to Day 43 (SAD), and Day 1 to Day 85 (MAD)
Pharmacokinetics (PK) of KRRO-110
Time Frame: Day 1 to Day 43 (SAD), and Day 1 to Day 85 (MAD)
PK profile of KRRO-110 half-life (t1/2), area under the concentration-time curve (AUC), and trough level (MAD cohorts only).
Day 1 to Day 43 (SAD), and Day 1 to Day 85 (MAD)

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.
Korro Bio, Inc.

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Study Director, Korro Bio, 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.
January 13, 2025

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, 2025

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.
December 15, 2025

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).
November 4, 2024

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.
November 5, 2024

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.
November 6, 2024

Study Record Updates

Last Update Posted (Actual)

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.
April 17, 2026

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.
April 14, 2026

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.
April 1, 2026

More Information

Terms related to this study

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.
  • KRRO-110-001

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

No

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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