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NCT Number: NCT07601425

Harmony-HHT: 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.

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Key information

Conditions

Hereditary Hemorrhagic Telangiectasia (HHT) Arteriovenous Malformations Cardiovascular Abnormalities Cardiovascular Diseases Congenital Abnormalities Congenital, Hereditary, and Neonatal Diseases and Abnormalities Disease Hematologic Diseases Hemic and Lymphatic Diseases Hemorrhagic Disorders Hemostatic Disorders Osler Weber Rendu Disease Pathologic Processes Pathological Conditions, Signs and Symptoms Telangiectasia, Hereditary Hemorrhagic Telangiectasis Vascular Diseases Vascular Malformations

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 1 / Phase 2

Primary location

Massachusetts General Hospital

Boston, Massachusetts, 02114, United States

Location status: Recruiting

Location contact

Study Director

CONTACT

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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)

Treatment and study plan

ATV-1601

Drug

Administered orally, daily

Other names: Active drug, capsule

Placebo

Drug

Administered orally, daily

Other names: Inactive, Placebo

Primary outcomes

  1. Part 1: Safety and tolerability

    Time frame: 16 weeks

    Number and severity of treatment-emergent adverse events (TEAEs) and study drug-related TEAEs

  2. Part 2: Safety and tolerability

    Time frame: 24 months

    Type, incidence, severity, timing, seriousness and relatedness of AEs and laboratory abnormalities

Secondary outcomes

  1. Part 1: Change in Epistaxis duration

    Time frame: 16 weeks

    28-day total duration compared to baseline

  2. Part 1: Epistaxis frequency

    Time frame: 16 weeks

    28-day frequency of nosebleeds compared to baseline

  3. Part 1: Epistaxis intensity

    Time frame: 16 weeks

    28-day average epistaxis intensity (6-point scale) of nosebleeds compared to baseline

  4. Part 1: Intensity-weighted epistaxis duration

    Time frame: 16 weeks

    28-day intensity-weighted duration of nosebleeds

  5. 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.

  6. Part 1: Change in Hemoglobin

    Time frame: 16 weeks

    Hemoglobin levels compared to baseline

  7. Part 1: Change in Parenteral iron use

    Time frame: 16 weeks

    Amount of parenteral iron administered compared to 16-weeks prior to treatment initiation

  8. 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

  9. Part 1: Pharmacokinetics - Maximum observed concentration (Cmax)

    Time frame: 16 Weeks

    Maximum plasma concentration

  10. 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

  11. 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

  12. Part 1: Pharmacokinetics - Time to maximum concentration (Tmax)

    Time frame: 16 Weeks

    Time to reach maximum plasma concentration

  13. Part 1: Pharmacokinetics - minimum concentration (Cmin)

    Time frame: 16 Weeks

    Pre-dose trough plasma concentration

  14. Part 1: Pharmacokinetics - Half-life (t½)

    Time frame: 16 Weeks

    Time required for plasma concentration to decrease by half

  15. Part 2: Epistaxis duration

    Time frame: Up to 2 years

    28-day total duration every 4 weeks

  16. Part 2: Epistaxis frequency

    Time frame: Up to 2 years

    Total number of nosebleeds every 4 weeks

  17. 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.

  18. Part 2: Change in Hemoglobin

    Time frame: Monthly during Part 2

    Hemoglobin levels compared to baseline

  19. 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

  20. 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

  21. 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

Study contacts

Contact information is provided by the study sponsor or research team.

Study Director

CONTACT

[email protected]

857-285-5400

Sponsors and collaborators

Lead sponsor

Atavistik Bio, Inc

Industry

Registry information

Official study title

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

Important dates

Study start
2026
Primary completion
2027
Study completion
2030
First posted
May 22, 2026
Registry last updated
Jul 30, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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