Harmony-HHT: ATV-1601 in Participants With Hereditary Hemorrhagic Telangiectasia (HHT)

May 15, 2026 updated by: Atavistik Bio, Inc

A Randomized, Placebo-Controlled, Double-Blind, Proof-of-Concept Study of ATV-1601 in Participants With Hereditary Hemorrhagic Telangiectasia (HHT)

This is a 2-part study evaluating ATV-1601 in participants with moderate to severe HHT. Part 1 is a randomized, double-blind, placebo-controlled study evaluating 3 dosing regimens of ATV-1601. Patients completing Part 1 may participate in the Part 2 open-label extension to receive ATV-1601.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Part 1: This is a Phase 1/2 proof-of-concept, double-blind, multicenter, placebo-controlled study to evaluate the safety, pharmacokinetics and efficacy of 3 oral dosing regimens of ATV-1601. Participants who meet eligibility requirements will be randomized in a double-blind manner to one of 3 doses of ATV-1601 or placebo. Participants will receive double-blind study treatment for a 16-week period.

Part 2: Eligible participants who complete Part 1 may enroll in an open-label extension study to receive up to 2 years of additional treatment. All participants in the open-label extension will receive ATV-1601. Once the recommended Phase 2 dose (RP2D) is determined based on Part 1, all participants in Part 2 will have the option to switch to the RP2D.

Study Type

Interventional

Enrollment (Estimated)

100

Phase

  • 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

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

Yes

Description

Inclusion Criteria:

  • Ability to provide informed consent prior to any study-specific procedures
  • Confirmed diagnosis of hereditary hemorrhagic telangiectasia (HHT) based on Curaçao criteria
  • Moderate to severe HHT with an ESS ≥ 4
  • Anemia at Screening and/or requirement for at least 1 red-cell unit (RUE) in the previous 6 months
  • Adequate hematologic, renal, and hepatic function per protocol-defined laboratory criteria
  • Use highly effective contraception during the study and for a protocol-defined period after last dose

Exclusion Criteria:

  • Clinically significant abnormalities of glucose metabolism including diagnosed Type 1 or uncontrolled Type 2 diabetes
  • Chronic cardiac disease, or cardiac rhythm abnormalities
  • History of significant cardiovascular, hepatic, renal, or hematologic disease not related to HHT that may confound study results
  • Use of prohibited concomitant medications within a protocol-defined washout period prior to first dose (including strong CYP modulators and certain herbal supplements)
  • Recent (within 6 weeks) major surgery or local ablative procedures, or procedures on nasal telangiectasias
  • Prior AKT inhibitor
  • Pregnant or breastfeeding women

Additional Criteria for Open-Label Extension:

  • Participants must complete the double-blind treatment period (Part 1)

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: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Part 1: 60 mg QD
Active drug, once daily
Drug: ATV-1601
Administered orally, daily
Other Names:
  • Active drug, capsule
Experimental: Part 1: 100 mg QD
Active drug, once daily
Drug: ATV-1601
Administered orally, daily
Other Names:
  • Active drug, capsule
Experimental: Part 1: 60 BID
Active drug, twice daily
Drug: ATV-1601
Administered orally, daily
Other Names:
  • Active drug, capsule
Experimental: Part 1: Placebo
Control Arm
Drug: Placebo
Administered orally, daily
Other Names:
  • Inactive, Placebo

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Part 1: Safety and tolerability
Time Frame: 16 weeks
Number and severity of treatment-emergent adverse events (TEAEs) and study drug-related TEAEs
16 weeks
Part 2: Safety and tolerability
Time Frame: 24 months
Type, incidence, severity, timing, seriousness and relatedness of AEs and laboratory abnormalities
24 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Part 1: Change in Epistaxis duration
Time Frame: 16 weeks
28-day total duration compared to baseline
16 weeks
Part 1: Epistaxis frequency
Time Frame: 16 weeks
28-day frequency of nosebleeds compared to baseline
16 weeks
Part 1: Epistaxis intensity
Time Frame: 16 weeks
28-day average epistaxis intensity (6-point scale) of nosebleeds compared to baseline
16 weeks
Part 1: Intensity-weighted epistaxis duration
Time Frame: 16 weeks
28-day intensity-weighted duration of nosebleeds
16 weeks
Part 1: Epistaxis Severity Score (ESS)
Time Frame: 16 weeks
The Epistaxis Severity Score (ESS) is a validated 6-question instrument with scores ranging from 0 to 10, where higher scores indicate more severe epistaxis symptoms.
16 weeks
Part 1: Change in Hemoglobin
Time Frame: 16 weeks
Hemoglobin levels compared to baseline
16 weeks
Part 1: Change in Parenteral iron use
Time Frame: 16 weeks
Amount of parenteral iron administered compared to 16-weeks prior to treatment initiation
16 weeks
Part 1: Change in Blood transfusion requirements
Time Frame: 16 Weeks
Amount of packed red blood cell (PRBC) transfusions and rate of transfusion independence compared to 16-weeks prior to treatment initiation
16 Weeks
Part 1: Pharmacokinetics - Maximum observed concentration (Cmax)
Time Frame: 16 Weeks
Maximum plasma concentration
16 Weeks
Part 1: Pharmacokinetics - Area under the concentration-time curve over the dosing interval (AUCtau)
Time Frame: 16 Weeks
Systemic exposure of ATV-1601 over the dosing interval
16 Weeks
Part 1: Pharmacokinetics - Area under the concentration-time curve extrapolated to infinity (AUCinf)
Time Frame: 16 Weeks
Total systemic exposure of ATV-1601 extrapolated to infinite time
16 Weeks
Part 1: Pharmacokinetics - Time to maximum concentration (Tmax)
Time Frame: 16 Weeks
Time to reach maximum plasma concentration
16 Weeks
Part 1: Pharmacokinetics - minimum concentration (Cmin)
Time Frame: 16 Weeks
Pre-dose trough plasma concentration
16 Weeks
Part 1: Pharmacokinetics - Half-life (t½)
Time Frame: 16 Weeks
Time required for plasma concentration to decrease by half
16 Weeks
Part 2: Epistaxis duration
Time Frame: Up to 2 years
28-day total duration every 4 weeks
Up to 2 years
Part 2: Epistaxis frequency
Time Frame: Up to 2 years
Total number of nosebleeds every 4 weeks
Up to 2 years
Part 2: Epistaxis Severity Score (ESS)
Time Frame: At 12 weeks and every 12 weeks thereafter up to study completion
Severity of nosebleeds using a score of 0-10 automatically calculated based on responses to 6 questions.
At 12 weeks and every 12 weeks thereafter up to study completion
Part 2: Change in Hemoglobin
Time Frame: Monthly during Part 2
Hemoglobin levels compared to baseline
Monthly during Part 2
Part 2: Parenteral iron use
Time Frame: At 12 weeks and every 12 weeks thereafter up to study completion
Total amount of parenteral iron infused (mg) compared to baseline (12 weeks prior to treatment initiation
At 12 weeks and every 12 weeks thereafter up to study completion
Part 2: Blood transfusion requirements
Time Frame: At 12 weeks and every 12 weeks thereafter during part 2
Total number of packed red blood cell (PRBC) transfusions (units) compared to baseline
At 12 weeks and every 12 weeks thereafter during part 2
Part 2: Transfusion independence
Time Frame: At 12 weeks and every 12 weeks thereafter during part 2
Proportion of participants who do not require PRBC transfusions
At 12 weeks and every 12 weeks thereafter during part 2

Collaborators and Investigators

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

Sponsor

Atavistik 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 (Estimated)

June 1, 2026

Primary Completion (Estimated)

December 1, 2027

Study Completion (Estimated)

March 1, 2030

Study Registration Dates

First Submitted

May 12, 2026

First Submitted That Met QC Criteria

May 15, 2026

First Posted (Actual)

May 22, 2026

Study Record Updates

Last Update Posted (Actual)

May 22, 2026

Last Update Submitted That Met QC Criteria

May 15, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • ATV-1601-102
  • Harmony-HHT (Other Identifier: Atavistik Bio Inc)

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

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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