DIAG723 in Adults With Hereditary Hemorrhagic Telangiectasia

This is a Phase 1/2, randomized, double-blind, placebo-controlled, first-in-human study evaluating the safety, tolerability, pharmacokinetics, and preliminary efficacy of subcutaneously administered DIAG723 in adult patients with hereditary hemorrhagic telangiectasia (HHT). The study consists of three parts: Part A (dose escalation): Single ascending subcutaneous doses of DIAG723 are evaluated in sequential cohorts to assess safety, tolerability, and pharmacokinetics. Part B (dose expansion): Multiple doses of DIAG723 administered over 13 weeks are evaluated in patients with HHT to assess safety and preliminary efficacy. Part C (dose expansion): Multiple doses of DIAG723 administered over 13 weeks are evaluated in patients with HHT and concomitant pulmonary arterial hypertension to assess safety and exploratory clinical effects in this population. Participants will be randomized within each study part to receive DIAG723 or placebo. The study includes dose escalation in Part A and dose expansion in Parts B and C.

Inclusion Criteria: * Adult patients ≥18 years with a clinical or genetic diagnosis of HHT * Adequate hepatic and renal function * Part B: Epistaxis and anemia or transfusion/iron history * Part C: HHT with documented pre-capillary pulmonary arterial hypertension Exclusion Criteria: * Active or recent systemic infection * Recent thromboembolic events * Use of anti-angiogenic drugs within 6 weeks * Pregnancy or lactation * Recent participation in another investigational study