A Phase 1/2 interventional study of ATV-1601 and Placebo in Hereditary Hemorrhagic Telangiectasia (HHT) and Osler Weber Rendu Disease, sponsored by Atavistik Bio, Inc. Recruiting at 10 sites in 2 countries. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-11-06.
Sponsored by Atavistik Bio, Inc · Phase 1/2, Interventional, and Treatment
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.
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.
106 studies on the registry are indexed under Telangiectasia, Hereditary Hemorrhagic; 24 are open to participants now.
This study's planned enrollment of 100 is above the median of 33 across 61 interventional studies indexed under Telangiectasia, Hereditary Hemorrhagic.
Browse Telangiectasia, Hereditary Hemorrhagic studies →Atavistik Bio, Inc is the lead sponsor of 2 studies on the registry; 1 is open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Additional Criteria for Open-Label Extension:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Washout period
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Active drug, once daily
Drug: ATV-1601
Active drug, once daily
Drug: ATV-1601
Active drug, twice daily
Drug: ATV-1601
Control Arm
Drug: Placebo
Administered orally, daily
Also known as: Active drug, capsule
Administered orally, daily
Also known as: Inactive, Placebo
Part 1: Safety and tolerability
Number and severity of treatment-emergent adverse events (TEAEs) and study drug-related TEAEs
Time frame: 16 weeks
Part 2: Safety and tolerability
Type, incidence, severity, timing, seriousness and relatedness of AEs and laboratory abnormalities
Time frame: 24 months
Part 1: Change in Epistaxis duration
28-day total duration compared to baseline
Time frame: 16 weeks
Part 1: Epistaxis frequency
28-day frequency of nosebleeds compared to baseline
Time frame: 16 weeks
Part 1: Epistaxis intensity
28-day average epistaxis intensity (6-point scale) of nosebleeds compared to baseline
Time frame: 16 weeks
Part 1: Intensity-weighted epistaxis duration
28-day intensity-weighted duration of nosebleeds
Time frame: 16 weeks
Part 1: Epistaxis Severity Score (ESS)
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.
Time frame: 16 weeks
Part 1: Change in Hemoglobin
Hemoglobin levels compared to baseline
Time frame: 16 weeks
Part 1: Change in Parenteral iron use
Amount of parenteral iron administered compared to 16-weeks prior to treatment initiation
Time frame: 16 weeks
Part 1: Change in Blood transfusion requirements
Amount of packed red blood cell (PRBC) transfusions and rate of transfusion independence compared to 16-weeks prior to treatment initiation
Time frame: 16 Weeks
Part 1: Pharmacokinetics - Maximum observed concentration (Cmax)
Maximum plasma concentration
Time frame: 16 Weeks
Part 1: Pharmacokinetics - Area under the concentration-time curve over the dosing interval (AUCtau)
Systemic exposure of ATV-1601 over the dosing interval
Time frame: 16 Weeks
Part 1: Pharmacokinetics - Area under the concentration-time curve extrapolated to infinity (AUCinf)
Total systemic exposure of ATV-1601 extrapolated to infinite time
Time frame: 16 Weeks
Part 1: Pharmacokinetics - Time to maximum concentration (Tmax)
Time to reach maximum plasma concentration
Time frame: 16 Weeks
Part 1: Pharmacokinetics - minimum concentration (Cmin)
Pre-dose trough plasma concentration
Time frame: 16 Weeks
Part 1: Pharmacokinetics - Half-life (t½)
Time required for plasma concentration to decrease by half
Time frame: 16 Weeks
Part 2: Epistaxis duration
28-day total duration every 4 weeks
Time frame: Up to 2 years
Part 2: Epistaxis frequency
Total number of nosebleeds every 4 weeks
Time frame: Up to 2 years
Part 2: Epistaxis Severity Score (ESS)
Severity of nosebleeds using a score of 0-10 automatically calculated based on responses to 6 questions.
Time frame: At 12 weeks and every 12 weeks thereafter up to study completion
Part 2: Change in Hemoglobin
Hemoglobin levels compared to baseline
Time frame: Monthly during Part 2
Part 2: Parenteral iron use
Total amount of parenteral iron infused (mg) compared to baseline (12 weeks prior to treatment initiation
Time frame: At 12 weeks and every 12 weeks thereafter up to study completion
Part 2: Blood transfusion requirements
Total number of packed red blood cell (PRBC) transfusions (units) compared to baseline
Time frame: At 12 weeks and every 12 weeks thereafter during part 2
Part 2: Transfusion independence
Proportion of participants who do not require PRBC transfusions
Time frame: At 12 weeks and every 12 weeks thereafter during part 2
Plan to share: No
No publications or documents are linked to this record.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Telangiectasia, Hereditary Hemorrhagic →
Atavistik Bio, Inc