A Trial to Assess the Efficacy and Safety of Engasertib in Participants With Moderate to Severe Hereditary Hemorrhagic Telangiectasia (HHT)

The primary objective of this trial is to assess the efficacy of engasertib 40 mg once daily (QD) in reducing the frequency of epistaxis compared to placebo QD during 28 weeks of double-blind treatment in participants with moderate to severe HHT.

Inclusion Criteria: 1. Participants are ≥18 years of age at the Screening Visit. 2. Participants have a definite diagnosis of HHT by the Curaçao criteria, defined as spontaneous and recurrent epistaxis and having at least 2 of the following criteria: 1. Multiple telangiectases at characteristic sites: lips, oral cavity, fingers, or nose; 2. Visceral lesions: gastrointestinal telangiectasia and/or pulmonary, hepatic, cerebral, or spinal arteriovenous malformations (AVMs); or 3. A first degree relative with HHT according to these criteria. 3. Participants must have an ESS \>4 at screening, and, in the judgement of the Investigator, participants are expected to have regular epistaxis that typically lasts for several minutes. This criterion is assessed at screening only and does not require reconfirmation prior to randomization on Day 1. 4. Participants have anemia OR in the prior 6 months have received a parenteral infusion of at least 250 mg of iron OR in the prior 6 months have received a red cell or whole blood transfusion. Exclusion Criteria: 1. History or current diagnosis of clinically significant electrocardiogram (ECG) abnormalities. 2. History of significant or uncontrolled skin disorders per Investigator's judgement. 3. Local ablative (eg, cauterization) or surgical procedures on nasal telangiectases \