Alpha-1 Anti-trypsin DeficiencyPhase 1/2REWRITENCT06677307
A Phase 1/2a, Single- and Multiple-dose Escalation Study of KRRO-110
A Phase 1/2 study testing KRRO-110 in people with Alpha-1 Anti-trypsin Deficiency and AATD, run by Korro Bio, Inc. at 5 sites in 2 countries.
Trial summary
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). Read more about this study
- Who is it for?
- Ages 18 to 70 yearsHealthy volunteers can take part
- Conditions the study is for
- Alpha-1 Anti-trypsin Deficiency, AATD
- What is being tested?
- KRRO-110
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 42 participants
- Where
- 5 sitesin 2 countries
- Study dates
- 13 Jan 2025to 15 Dec 2025
- Phase
- Phase 1/2
- 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 18 to 70 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- 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
Who cannot join
- 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)
Show all 16Show fewer
- Respiratory or other acute illness within 8 weeks
- Tobacco use of any kind within 6 months
- 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
Trial locations and contacts
5 sites in 2 countries.
5 sites in 2 countries
Australia3 sites
The Prince Charles Hospital
Brisbane, Queensland, 4032
Nucleus Network Pty Ltd
Melbourne, Victoria, 3004
St. Vincent's Hospital Melbourne
Melbourne, Victoria, 3065
New Zealand2 sites
New Zealand Clinical Research
Auckland
New Zealand Clinical Research
Christchurch
About this study
Official title: 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).
- Conditions
- Alpha-1 Anti-trypsin Deficiency, AATD
- Being tested
- KRRO-110
- Medical subject headings
- alpha 1-Antitrypsin Deficiency
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
KRRO-110Drug
KRRO-110 drug product, IV
| Study group | Role | What they receive |
|---|---|---|
| Arm 1: KRRO-110 (Part A and Part B) | Experimental | 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). Receives: Drug: KRRO-110 |
| Arm 2: Placebo (Part A only) | Placebo comparator | Placebo, IV administration Receives: Drug: KRRO-110 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Safety and Tolerability
Type, frequency, and severity of treatment-emergent adverse events (TEAEs)
Measured: From Day 1 to Day 43 in the SAD and from Day 1 to Day 85 in the MAD
Secondary outcomes (3)
Pharmacokinetics (PK) of KRRO-110
PK profile of KRRO-110 including maximum blood concentration (Cmax)
Measured: Day 1 to Day 43 (SAD), and Day 1 to Day 85 (MAD)
Pharmacodynamics (PD) of KRRO-110
PD profile of KRRO-110 based on change from Baseline in alpha-antitrypsin (AAT) enzyme levels at all measured timepoints (PiZZ participants only).
Measured: Day 1 to Day 43 (SAD), and Day 1 to Day 85 (MAD)
Pharmacokinetics (PK) of KRRO-110
PK profile of KRRO-110 half-life (t1/2), area under the concentration-time curve (AUC), and trough level (MAD cohorts only).
Measured: Day 1 to Day 43 (SAD), and Day 1 to Day 85 (MAD)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Nov 2024
- Study start13 Jan 2025
- Primary completion31 Oct 2025
- Study completion15 Dec 2025
Why it stopped: The study was terminated for business decision reasons.
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Alpha-1 Anti-trypsin 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 1/2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Sequential
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 42 participants (actual)
Sponsor and investigators
- Lead sponsor
- Korro Bio, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Study Director, Study director, Korro Bio, Inc.
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06677307
- Sponsor's protocol ID
- KRRO-110-001
- Acronym
- REWRITE
- Status last verified
- Apr 2026
- First submitted
- 4 Nov 2024
- Last updated
- 17 Apr 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 17 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- 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)
- ClinicalTrials.gov ID
- NCT06677307
- Acronym / sponsor ID
- REWRITE / KRRO-110-001
- Conditions
- Alpha-1 Anti-trypsin Deficiency, AATD
- Phase
- Phase 1/2
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: The study was terminated for business decision reasons.
- Enrolment
- 42 participants (actual)
- Lead sponsor
- Korro Bio, Inc.Industry (pharma, biotech, devices)
- Study start
- 13 Jan 2025 (actual)
- Primary completion
- 31 Oct 2025 (actual)
- Study completion
- 15 Dec 2025 (actual)
- First posted
- 6 Nov 2024 (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 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 design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Sequential
- Masking
- Double blind (participant, investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Arm 1: KRRO-110 (Part A and Part B) | Experimental | Drug: KRRO-110KRRO-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). |
| Arm 2: Placebo (Part A only) | Placebo comparator | Drug: KRRO-110Placebo, IV administration |
Who may qualify
- Ages
- 18 to 70 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (8 listed)
- 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)
Key exclusion criteria (16 listed)
- 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
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 |
|---|---|---|
| KRRO-110KRRO-110 drug product, IV | Drug | Arm 1: KRRO-110 (Part A and Part B), Arm 2: Placebo (Part A only) |
Primary outcome
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)
3 secondary outcomes
Pharmacokinetics (PK) of KRRO-110
Time frame: 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)
Pharmacokinetics (PK) of KRRO-110
Time frame: Day 1 to Day 43 (SAD), and Day 1 to Day 85 (MAD)
Results and safety
The study was stopped early (reason given: The study was terminated for business decision reasons.). Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 17 Apr 2026.
- 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.
Study Director study director
Korro Bio, Inc.
5 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1/2 study testing KRRO-110 in people with Alpha-1 Anti-trypsin Deficiency and AATD, run by Korro Bio, Inc. at 5 sites in 2 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 8 inclusion and 16 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 17 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 5 sites in Australia, New Zealand. 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 combined phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
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 for business decision reasons.). 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?
Safety and Tolerability (time frame: From Day 1 to Day 43 in the SAD and from Day 1 to Day 85 in the MAD). 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 17 Apr 2026.