DIAG723 in Adults With Hereditary Hemorrhagic Telangiectasia

Sponsor
Diagonal Therapeutics, Inc.
Study ID
NCT07623525
Phase
PHASE1/PHASE2
Status
Recruiting
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Conditions

  • Hereditary Hemorrhagic Telangiectasia
  • Pulmonary Arterial Hypertension

Eligibility Criteria

Sex
ALL
Age
18 Years - N/A
Healthy Volunteers
Not accepted

Interventions

  • DIAG723 — BIOLOGICAL
    Bispecific agonist monoclonal antibody targeting ALK-1 and BMPRII, administered subcutaneously as: Single ascending dose in Part A; Multiple doses (7 doses over 13 weeks) in Parts B and C
  • Placebo — OTHER
    Sterile normal saline (0.9% NaCl) administered subcutaneously in volumes matched to DIAG723 to maintain study blinding.

Study Details

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.

Key Dates

First listed
Jun 3, 2026
Start date
Jun 4, 2026
Status verified
Jul 2026
Primary completion
Nov 30, 2027
Completion
Dec 31, 2027

Study Design

Enrollment
93 participants (estimated)
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT

Arms

  • Experimental: DIAG723
    Participants receive DIAG723 administered subcutaneously. Part A (dose-escalation): Single ascending dose across planned cohorts, randomized 3:1 DIAG723:placebo. Part B (multi-dose HHT): Multiple-dose regimens over 13 weeks (7 doses administered every other week), randomized 2:1. Part C (multi-dose HHT + PAH): Same 13-week multi-dose regimen in patients with pulmonary arterial hypertension, randomized 4:1. Doses/regimens in Parts B and C are selected based on Part A safety and PK data.
  • Placebo Comparator: Placebo Comparator
    Participants receive placebo (sterile normal saline, 0.9% NaCl) administered subcutaneously in a volume matched to DIAG723 to maintain blinding. Matching single-dose administration in Part A. Matching multi-dose regimens (every-other-week dosing for 13 weeks) in Parts B and C. Randomization ratios consistent with each study part (3:1, 2:1, 4:1).

Primary Outcome Measure

Incidence of Treatment-Emergent Adverse Events (TEAEs) - Part A (Single Dose) [ Time Frame: From first dose through Day 28 ]

Central Contacts

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