A Long-term Study of KT-621 Administered Orally to Participants With Asthma Previously Enrolled in a KT-621 Asthma Study (BREADTH-EXT)

June 24, 2026 updated by: Kymera Therapeutics, Inc.

A Multicenter, Open-Label, Long-Term Extension Study to Evaluate the Long-Term Safety and Tolerability of KT-621 in Participants With Asthma Previously Enrolled in a KT-621 Asthma Study

This Phase 2b open-label, long-term extension study is designed to evaluate the long-term safety and efficacy of KT-621 in participants with asthma who were previously enrolled in the parent study (KT621-AS-202) of KT-621 for asthma. The main goals of this study are to investigate the long-term safety and tolerability of KT-621, the long-term efficacy of KT-621 at treating asthma, and how KT-621 behaves in the body long-term.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

264

Phase

  • Phase 2

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 Locations

  • United States
    • Florida
      • Tampa, Florida, United States, 33607
        • Recruiting
        • Kymera Investigative Site

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

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Must have completed all visits of the parent study, per its protocol, up to the end of treatment (EoT) visit.
  • Must be willing and able to comply with scheduled visits, treatment plan, laboratory tests, other study-related procedures, and questionnaires, including completing the electronic diary (e-diary), for the duration of the study as required by the study protocol.
  • Must agree to contraceptive requirements in compliance with the clinical study and local requirements.

Exclusion Criteria:

  • Must not have experienced any clinically significant change in health status during the parent study, which, in the opinion of the Investigator, would interfere with participant safety, study evaluations, or compliance with study procedures; or otherwise make the participant unsuitable for participation in this study.
  • Must not have developed an AE during the parent study, that in the opinion of the Investigator or of the Sponsor's Medical Monitor, could indicate that continued treatment may present an unreasonable risk for the participant.
  • Must not have met permanent discontinuation criteria and/or permanently discontinued study treatment for any reason during the parent study.
  • Must not be a member of the Sponsor or site's investigational team or their immediate family.
  • Must not be unsuitable to enter the study for any other reason, as judged by the Investigator, including potential risk of noncompliance to study procedures.

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: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: KT-621
Drug: KT-621
Oral drug

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Incidence of treatment-emergent adverse events (TEAEs)
Time Frame: From baseline through Week 52
From baseline through Week 52
Incidence of treatment-emergent serious adverse events (SAEs)
Time Frame: From baseline through Week 52
From baseline through Week 52

Secondary Outcome Measures

Outcome Measure
Time Frame
Change from baseline in pre-bronchodilator FEV1
Time Frame: From baseline (as assessed in the parent study) to Week 52
From baseline (as assessed in the parent study) to Week 52
Change from baseline in post-bronchodilator FEV1
Time Frame: From baseline (as assessed in the parent study) to Week 52
From baseline (as assessed in the parent study) to Week 52
Change from baseline in Asthma Control Questionnaire 5-question version (ACQ-5) score
Time Frame: From baseline (as assessed in the parent study) to Week 52
From baseline (as assessed in the parent study) to Week 52
Change from baseline in Standardized Asthma Quality of Life Questionnaire [AQLQ(S)] global Score
Time Frame: From baseline (as assessed in the parent study) to Week 52
From baseline (as assessed in the parent study) to Week 52
Plasma concentration of KT-621 derived from plasma concentration time data
Time Frame: From baseline to Week 52
From baseline to Week 52

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Kymera Therapeutics, 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 (Estimated)

July 1, 2026

Primary Completion (Estimated)

December 1, 2028

Study Completion (Estimated)

December 1, 2028

Study Registration Dates

First Submitted

June 24, 2026

First Submitted That Met QC Criteria

June 24, 2026

First Posted (Actual)

June 30, 2026

Study Record Updates

Last Update Posted (Actual)

June 30, 2026

Last Update Submitted That Met QC Criteria

June 24, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • KT621-AS-203

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

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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