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A Phase 3 Study of Engasertib to Evaluate Safety and Effectiveness in Adults with Moderate to Severe Hereditary Hemorrhagic Telangiectasia

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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study focuses on Hereditary Hemorrhagic Telangiectasia (HHT), a rare inherited condition that causes abnormal blood vessels and often leads to frequent nosebleeds, known medically as epistaxis. The investigational medication being tested is an oral capsule containing Engasertib taken once daily, compared with a matching inactive pill (placebo). Engasertib is a new drug that is being evaluated for its ability to lessen the number of nosebleeds experienced by people with moderate to severe HHT.

The purpose of the trial is to determine whether daily treatment with Engasertib reduces the frequency of epistaxis compared with placebo over a period of about 28 weeks. Participants will receive either the study drug or placebo each day, keep a simple diary to record each nosebleed event, and attend regular clinic visits where basic health checks and blood work are performed to monitor safety. The study is conducted in a double-blind manner, meaning that neither the participants nor the study staff know which treatment is being taken, which helps ensure unbiased results.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial visit and baseline assessments

    You attend the first study visit after joining the trial. during this visit, the study team confirms that you meet the eligibility criteria for hereditary hemorrhagic telangiectasia (hht).

    You receive training on how to use the electronic diary (ediary) to record each nosebleed event, its duration, and any related symptoms.

  2. Step 2

    Randomization to study medication

    After baseline assessments, you are randomly assigned to receive either engasertib or a matching placebo. the assignment is double‑blind, meaning neither you nor the study staff know which product you receive.

  3. Step 3

    Start of study medication

    You begin taking one oral capsule each day (once daily, abbreviated qd). the capsule contains 40 mg of engasertib if you are in the active group, or an identical‑looking capsule with no active drug if you are in the placebo group.

    The medication is taken for a total of 28 weeks, which constitutes the double‑blind treatment period.

  4. Step 4

    Daily recording of nosebleeds

    Every day you log each nosebleed (epistaxis) event in the electronic diary. you record the number of events, how long each lasted, and any related symptoms.

  5. Step 5

    Periodic safety and symptom assessments

    Throughout the 28‑week period you attend scheduled clinic visits where the study team checks your health, reviews the diary entries, and asks you to complete questionnaires that measure the severity of nosebleeds and related quality‑of‑life impacts.

  6. Step 6

    End of double‑blind treatment (week 28)

    At the end of week 28 you stop taking the study medication. a final set of assessments is performed, including the electronic diary summary, the epistaxis severity score (ess) questionnaire, and the nose hht questionnaire.

    The data collected will be used to compare the total number of nosebleeds, total duration of bleeding, and other health measures between the engasertib and placebo groups.

Who can join the trial?

5 criteria

  • You must be 18 years old or older on the day you are screened for the study.
  • You need a confirmed diagnosis of Hereditary Hemorrhagic Telangiectasia (HHT) using the Curaçao criteria. This means you have frequent nosebleeds that happen on their own, plus at least two of the following: multiple small red spots called telangiectases on the lips, inside the mouth, fingers, or nose; internal organ problems such as bleeding spots in the stomach or abnormal blood vessel connections (called arteriovenous malformations) in the lungs, liver, brain, or spine; or a close family member (parent, sibling, or child) who also meets these criteria.
  • You must have an Epistaxis Severity Score (ESS) greater than 4 at the screening visit, and the doctor must think you will have regular nosebleeds that last several minutes. This score is only checked once before you start the study.
  • You need to have low blood iron levels (called anemia) defined as a hemoglobin level below 13 g/dL for men or below 12 g/dL for women, or you must have received either an iron infusion of at least 250 mg, or a red‑cell or whole‑blood transfusion, within the past six months.
  • If you have pre‑diabetes, it must be stable, and if you have diabetes, it must be well‑controlled with a glycosylated hemoglobin (HbA1c) level of 8.0% or lower.

Who cannot join the trial?

5 criteria

  • Having a past or current serious skin disorder that is not well‑controlled, as judged by the doctor.
  • Having had any local treatment that destroys tissue (such as cauterization) or surgery on the small blood‑vessel growths in the nose (nasal telangiectases) within 6 weeks before the screening visit.
  • Using medicines that stop new blood vessels from forming (anti‑angiogenic drugs) – for example, bevacizumab, pazopanib, thalidomide, lenalidomide, pomalidomide, tacrolimus, sirolimus, tamoxifen, raloxifene, or bazedoxifene – within 6 weeks before the screening visit.
  • Taking oral tranexamic acid or epsilon‑aminocaproic acid (both help blood clotting) unless the dose has been stable for at least 4 weeks before screening and will stay the same throughout the study.
  • Having uncontrolled high blood pressure (hypertension) at the screening visit. Blood pressure must be stable on medication before you can be randomly assigned to a treatment group.
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Investigated drugs

Engasertib is an oral capsule being studied as a treatment for hereditary hemorrhagic telangiectasia (HHT). It is intended to reduce how often patients experience nosebleeds. The medication is taken once daily for several months while researchers watch for any side effects and check how well it works to lower the frequency of epistaxis. It is classified as an orphan drug, meaning it is designed for a rare disease.

What is already known about the treatment

  • Engasertib

    Engasertib is taken as a hard‑gelatin capsule taken by mouth, 40 mg once each day. It is an investigational orphan drug that is currently being studied in a Phase 3 trial and is not yet approved for general medical use. The medicine is being tested to help people with hereditary hemorrhagic telangiectasia (HHT) by lowering the number of nosebleeds they experience. Engasertib works by blocking specific proteins that control abnormal blood‑vessel growth, and it is classified as an oral small‑molecule anti‑angiogenic agent.

  • Engasertib Placebo

    The placebo looks like a hard‑gelatin capsule taken by mouth, but it contains no active ingredient and is given once daily. It is used only in clinical studies to serve as a comparison for the active drug and has no therapeutic effect on its own. The placebo helps researchers determine whether any improvement in HHT symptoms is due to Engasertib or other factors. It is classified as an inert control substance in the trial.

Investigated diseases

Hereditary Hemorrhagic Telangiectasia - Hereditary hemorrhagic telangiectasia is an inherited condition that causes fragile, enlarged blood vessels called telangiectasias. These abnormal vessels often appear on the skin, lips, and inside the nose, leading to frequent nosebleeds. Over time, similar lesions can develop in the lungs, liver, and brain, creating abnormal connections between arteries and veins. The disorder usually progresses slowly, with bleeding episodes becoming more common as a person gets older. Because the vessels are delicate, even minor trauma can trigger bleeding.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-524490-17-00Protocol codeHHT-301Estimated enrolment240 patientsSponsorVaderis Therapeutics AG

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