Hereditary Hemorrhagic TelangiectasiaPhase 1/2DIAMONDNCT07623525
DIAG723 in Adults With Hereditary Hemorrhagic Telangiectasia
A Phase 1/2 study testing DIAG723 in people with Hereditary Hemorrhagic Telangiectasia and Pulmonary Arterial Hypertension, run by Diagonal Therapeutics, Inc. at 11 sites in 3 countries.
Trial summary
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). Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Hereditary Hemorrhagic Telangiectasia, Pulmonary Arterial Hypertension
- What is being tested?
- DIAG723
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 93 participants
- Where
- 11 sitesin 3 countries
- Study dates
- 4 Jun 2026to 31 Dec 2027
- Phase
- Phase 1/2
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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
Who cannot join
- 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
Trial locations and contacts
11 sites in 3 countries. Contact the study team or a site near you to ask about taking part.
11 sites in 3 countries
Australia7 sites, 6 recruiting
- Not yet recruiting
Diagonal Investigational Site
Camperdown, New South Wales, 2050
- Recruiting
Diagonal Investigational Site
East Melbourne, Victoria, 3002
- Not yet recruiting
Diagonal Investigational Site
Herston, Queensland, 4029
- Withdrawn
Diagonal Investigational Site
Herston, Queensland, 4029
- Not yet recruiting
Diagonal Investigational Site
Parkville, Victoria, 3052
- Recruiting
Diagonal Investigational Site
Randwick, New South Wales, 2031
- Not yet recruiting
Diagonal Investigational Site
West Perth, Western Australia, 6005
Canada3 sites, 3 recruiting
- Not yet recruiting
Diagonal Investigational Site
Laval, Quebec, H7V 4B3
- Not yet recruiting
Diagonal Investigational Site
Toronto, Ontario, M5B1W8
- Not yet recruiting
Diagonal Investigational Site
Toronto, Ontario, M9L 3A2
New Zealand1 site, 1 recruiting
- Recruiting
Diagonal Investigational Site
Grafton, Auckland, 1010
About this study
Official title: A Phase 1/2, First-in-Human, Multicenter, Ascending Single-Dose and Multi-Dose Study to Assess the Safety of DIAG723, a Novel Bispecific ALK-1 and BMPRII Agonist Antibody in Adult Patients With Hereditary Hemorrhagic Telangiectasia (DIAMOND Trial)
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:
Read more
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.
Read the detailed description
This is a Phase 1/2, randomized, double-blind, placebo-controlled, first-in-human, multicenter study designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary clinical activity of DIAG723, a bispecific agonist monoclonal antibody targeting activin receptor-like kinase 1 (ALK-1) and bone morphogenetic protein receptor type II (BMPRII), in adult patients with hereditary hemorrhagic telangiectasia (HHT).
The study is conducted in three sequential parts (Parts A, B, and C), each evaluating different dosing strategies and patient populations.
Part A (Single Ascending DoseDose in HHT):
Part A is a dose-escalation phase evaluating ascending single-dose levels of DIAG723 administered subcutaneously in sequential cohorts. Within each cohort, participants are randomized to receive DIAG723 or placebo. Dose escalation proceeds in a stepwise manner following review of safety, tolerability, and pharmacokinetic data. Sentinel dosing is implemented to allow for early safety assessment prior to dosing additional participants. Participants are monitored in an inpatient setting following dosing, with continued outpatient follow-up through the end of the assessment period.
Part B (Multiple-Dose Expansion in HHT):
Part B evaluates the safety, tolerability, pharmacokinetics, and preliminary clinical activity of DIAG723 administered as a multiple-dose regimen in patients with HHT symptoms. Participants are randomized to receive DIAG723 or placebo and receive repeated subcutaneous administrations over a planned treatment period of approximately 13 weeks. Dose levels and regimens evaluated in Part B are informed by available safety, pharmacokinetic, and pharmacodynamic data from Part A. An independent data monitoring process is used to support dose selection and cohort progression.
Part C (Multiple-Dose Expansion in HHT with Pulmonary Arterial Hypertension):
Part C evaluates the safety, tolerability, pharmacokinetics, and clinical effects of DIAG723 in a population of patients with HHT and concomitant pulmonary arterial hypertension. Participants are randomized to receive DIAG723 or placebo and receive the same general multiple-dose treatment approach as in Part B. Dose selection for Part C is informed by cumulative data from Part A and Part B, with additional assessments conducted to characterize effects in this specific patient population.
Across all study parts, participants are randomized using an interactive response system, and study treatment is administered under double-blind conditions. A Safety Review Committee and an independent Data Safety Monitoring Board provide ongoing review of safety data and support dose-escalation and progression decisions throughout the study. Dose escalation and cohort progression are guided by predefined safety criteria and overall risk-benefit assessment.
All doses are administered by subcutaneous injection, and participants undergo safety monitoring, pharmacokinetic sampling, and clinical assessments at scheduled study visits. The study includes both inpatient and outpatient components depending on the study part and stage of participation.
This study is designed to characterize the safety profile and pharmacokinetic properties of DIAG723 and to support selection of appropriate doses and regimens for further clinical development in HHT.
- Being tested
- DIAG723, Placebo
- Keywords
- Hereditary Hemorrhagic Telangiectasia, HHT, BMPRII, ALK1, Bone morphogenetic protein receptor type II
- Medical subject headings
- Telangiectasia, Hereditary Hemorrhagic, Pulmonary Arterial Hypertension
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
DIAG723Biological
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
PlaceboOther
Sterile normal saline (0.9% NaCl) administered subcutaneously in volumes matched to DIAG723 to maintain study blinding.
| Study group | Role | What they receive |
|---|---|---|
| DIAG723 | Experimental | 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. Receives: Biological: DIAG723 |
| 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). Receives: Other: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Incidence of Treatment-Emergent Adverse Events (TEAEs) - Part A (Single Dose)
Number and proportion of participants experiencing TEAEs following single-dose administration of DIAG723.
Measured: From first dose through Day 28
Incidence of Serious Adverse Events (SAEs) - Part A (Single Dose)
Number and proportion of participants experiencing SAEs following single-dose administration of DIAG723.
Measured: From first dose through Day 28
Incidence of Dose-Limiting Toxicities (DLTs) - Part A (Single Dose)
Number and proportion of participants experiencing DLTs during the dose-escalation period following single-dose administration.
Measured: From first dose through Day 28
Number of participants with abnormal laboratory tests results - Part A (Single Dose)
Laboratory assessments include hematology (complete blood count), clinical chemistry (basic metabolic panel; liver function tests; renal function; electrolytes; thyroid-stimulating hormone, free T4, free T3; cortisol; luteinizing hormone; lipase; amylase), coagulation (prothrombin time/international normalized ratio, activated partial thromboplastin time), and urinalysis.
Measured: Baseline through Day 28
Number of participants with abnormal vital signs - Part A (Single Dose)
Vital sign measurements include body temperature, heart rate, respiratory rate, blood pressure, and oxygen saturation.
Measured: Baseline through Day 28
Change from Baseline in Electrocardiogram (ECG) Parameters - Part A (Single Dose)
Change from baseline in ECG parameters, including QTc interval.
Measured: Baseline through Day 28
Incidence of Treatment-Emergent Adverse Events (TEAEs) - Part B (Multiple Dose)
Number and proportion of participants experiencing TEAEs following multiple-dose administration of DIAG723.
Measured: From first dose through 28 days after final dose
Incidence of Serious Adverse Events (SAEs) - Part B (Multiple Dose)
Number and proportion of participants experiencing SAEs following multiple-dose administration.
Measured: From first dose through 28 days after final dose
Incidence of Dose-Limiting Toxicities (DLTs) - Part B (Multiple Dose)
Number and proportion of participants experiencing DLTs during multiple-dose treatment.
Measured: From first dose through 28 days after final dose
Number of participants with abnormal laboratory tests results - Part B (Multiple Dose)
Laboratory assessments include hematology (complete blood count), clinical chemistry (basic metabolic panel; liver function tests; renal function; electrolytes; thyroid-stimulating hormone, free T4, free T3; cortisol; luteinizing hormone; lipase; amylase), coagulation (prothrombin time/international normalized ratio, activated partial thromboplastin time), and urinalysis.
Measured: Baseline through Week 15
Number of participants with abnormal vital signs - Part B (Multiple Dose)
Vital sign measurements include body temperature, heart rate, respiratory rate, blood pressure, and oxygen saturation.
Measured: Baseline through Week 17
Change from Baseline in Electrocardiogram (ECG) Parameters - Part B (Multiple Dose)
Change from baseline in ECG parameters, including QTc interval.
Measured: Baseline through Week 17
Incidence of Treatment-Emergent Adverse Events (TEAEs) - Part C (Multiple Dose, HHT with PAH)
Number and proportion of participants experiencing TEAEs following multiple-dose administration in participants with HHT and pulmonary arterial hypertension.
Measured: From first dose through 28 days after final dose
Incidence of Serious Adverse Events (SAEs) - Part C (Multiple Dose, HHT with PAH)
Number and proportion of participants experiencing SAEs in this population.
Measured: From first dose through 28 days after final dose
Incidence of Dose-Limiting Toxicities (DLTs) - Part C (Multiple Dose, HHT with PAH)
Number and proportion of participants experiencing DLTs during treatment.
Measured: From first dose through 28 days after final dose
Number of participants with abnormal laboratory tests results - Part C (Multiple Dose, HHT with PAH)
Laboratory assessments include hematology (complete blood count), clinical chemistry (basic metabolic panel; liver function tests; renal function; electrolytes; thyroid-stimulating hormone, free T4, free T3; cortisol; luteinizing hormone; lipase; amylase), coagulation (prothrombin time/international normalized ratio, activated partial thromboplastin time), and urinalysis.
Measured: Baseline through Week 15
Number of participants with abnormal vital signs - Part C (Multiple Dose, HHT with PAH)
Vital sign measurements include body temperature, heart rate, respiratory rate, blood pressure, and oxygen saturation.
Measured: Baseline through Week 17
Change from Baseline in Electrocardiogram (ECG) Parameters - Part C (Multiple Dose, HHT with PAH)
Change from baseline in ECG parameters, including QTc interval.
Measured: Baseline through Week 17
Secondary outcomes (20)
Area Under the Plasma Concentration-Time Curve (AUC) of DIAG723 - Part A
Plasma AUC following single-dose administration of DIAG723.
Measured: Pre-dose through Day 28
Maximum Observed Plasma Concentration (Cmax) of DIAG723 - Part A
Maximum observed plasma concentration following single-dose administration.
Measured: Pre-dose through Day 28
Time to Maximum Plasma Concentration (Tmax) of DIAG723 - Part A
Time to reach maximum plasma concentration following single-dose administration.
Measured: Pre-dose through Day 28
Area Under the Plasma Concentration-Time Curve (AUC) of DIAG723 - Part B (Multiple Dose)
Plasma AUC following repeated dosing of DIAG723.
Measured: Pre-dose through 28 days after final dose
Maximum Observed Plasma Concentration (Cmax) of DIAG723 - Part B (Multiple Dose)
Maximum observed plasma concentration following multiple-dose administration.
Measured: Pre-dose through 28 days after final dose
Time to Maximum Plasma Concentration (Tmax) of DIAG723 - Part B (Multiple Dose)
Time to reach maximum plasma concentration following multiple-dose administration.
Measured: Pre-dose through 28 days after final dose
Incidence of Anti-Drug Antibodies (ADA) to DIAG723 - Part A (Single Dose)
Number and proportion of participants with detectable anti-drug antibodies following single-dose administration.
Measured: From first dose through Day 28
Incidence of Anti-Drug Antibodies (ADA) to DIAG723 - Part B (Multiple Dose)
Number and proportion of participants with detectable anti-drug antibodies following multiple-dose administration.
Measured: From first dose through 28 days after final dose
Change from Baseline in Epistaxis Frequency - Part B (Multiple Dose)
Change from baseline in frequency of epistaxis events as recorded in a participant-reported electronic daily diary.
Measured: Baseline through end of treatment (13 weeks)
Change from Baseline in Epistaxis Flow Intensity, Duration, and Intensity-Adjusted Duration - Part B (Multiple Dose)
Change from baseline in epistaxis flow intensity, event duration, and intensity-adjusted duration as recorded in an electronic daily diary.
Measured: Baseline through end of treatment (13 weeks)
Change from Baseline in Hemoglobin - Part B (Multiple Dose)
Change from baseline in hemoglobin concentration.
Measured: Baseline through Week 15
Change from Baseline in Hematocrit - Part B (Multiple Dose)
Change from baseline in hematocrit.
Measured: Baseline through Week 15
Change in Mean Corpuscular Volume (MCV) Following Multi-dose Treatment With DIAG723 (Part B)
Change from baseline in mean corpuscular volume (MCV, fL) during Part B following multi-dose treatment with DIAG723.
Measured: Baseline through Week 15
Change from Baseline in Red Blood Cell Count Following Multi-dose Treatment With DIAG723
Measured: Baseline through Week 15
Change from Baseline in White Blood Cell Count Following Multi-dose Treatment With DIAG723 (Part B)
Measured: Baseline through Week 15
Change from Baseline in Platelet Count Following Multi-dose Treatment With DIAG723 (Part B)
Measured: Baseline through Week 15
Change in Red Blood Cell (RBC) Units Transfused During Treatment With DIAG723 (Part B)
Change from baseline in the number of RBC units transfused, comparing a pre-treatment baseline period to the on-treatment period during Part B.
Measured: Baseline through Week 15
Change in Elemental Iron Infused During Treatment With DIAG723 (Part B)
Change from baseline in total milligrams of elemental iron administered via infusion, comparing a pre-treatment baseline period to the on-treatment period during Part B.
Measured: Baseline through Week 15
Change in Hematologic Support Score (HSS) Following Treatment With DIAG723 (Part B)
The Hematologic Support Score ranges from 0 to 100, with higher scores indicating greater transfusion and iron supplementation burden and worse outcomes.
Measured: Baseline through Week 17
Change in Hematologic Impact Score (HIS) Following Treatment With DIAG723 (Part B)
The Hematologic Impact Score ranges from 0 to 100, with higher scores indicating greater hematologic disease burden and worse outcomes.
Measured: Baseline through Week 17
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Jun 2026
- Study start4 Jun 2026
- Primary completion30 Nov 2027 (estimated)
- Study completion31 Dec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Hereditary Hemorrhagic TelangiectasiaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 1/2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- This is a 3-part sequential study (Parts A, B, and C) with separate randomization within each part
- Masking
- Triple blind
- Who is masked
- Participant, Care provider, Investigator
- Enrolment
- 93 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Diagonal Therapeutics, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07623525
- Sponsor's protocol ID
- DIAG723-PT-CL-001
- Acronym
- DIAMOND
- Status last verified
- Sep 2026
- First submitted
- 19 May 2026
- Last updated
- 8 Sep 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 8 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 1/2, First-in-Human, Multicenter, Ascending Single-Dose and Multi-Dose Study to Assess the Safety of DIAG723, a Novel Bispecific ALK-1 and BMPRII Agonist Antibody in Adult Patients With Hereditary Hemorrhagic Telangiectasia (DIAMOND Trial)
- ClinicalTrials.gov ID
- NCT07623525
- Acronym / sponsor ID
- DIAMOND / DIAG723-PT-CL-001
- Keywords
- Hereditary Hemorrhagic Telangiectasia, HHT, BMPRII, ALK1, Bone morphogenetic protein receptor type II
- Phase
- Phase 1/2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 93 participants (estimated)
- Lead sponsor
- Diagonal Therapeutics, Inc.Industry (pharma, biotech, devices)
- Study start
- 4 Jun 2026 (actual)
- Primary completion
- 30 Nov 2027 (estimated)
- Study completion
- 31 Dec 2027 (estimated)
- First posted
- 3 Jun 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
This is a Phase 1/2, randomized, double-blind, placebo-controlled, first-in-human, multicenter study designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary clinical activity of DIAG723, a bispecific agonist monoclonal antibody targeting activin receptor-like kinase 1 (ALK-1) and bone morphogenetic protein receptor type II (BMPRII), in adult patients with hereditary hemorrhagic telangiectasia (HHT).
The study is conducted in three sequential parts (Parts A, B, and C), each evaluating different dosing strategies and patient populations.
Part A (Single Ascending DoseDose in HHT):
Part A is a dose-escalation phase evaluating ascending single-dose levels of DIAG723 administered subcutaneously in sequential cohorts. Within each cohort, participants are randomized to receive DIAG723 or placebo. Dose escalation proceeds in a stepwise manner following review of safety, tolerability, and pharmacokinetic data. Sentinel dosing is implemented to allow for early safety assessment prior to dosing additional participants. Participants are monitored in an inpatient setting following dosing, with continued outpatient follow-up through the end of the assessment period.
Part B (Multiple-Dose Expansion in HHT):
Part B evaluates the safety, tolerability, pharmacokinetics, and preliminary clinical activity of DIAG723 administered as a multiple-dose regimen in patients with HHT symptoms. Participants are randomized to receive DIAG723 or placebo and receive repeated subcutaneous administrations over a planned treatment period of approximately 13 weeks. Dose levels and regimens evaluated in Part B are informed by available safety, pharmacokinetic, and pharmacodynamic data from Part A. An independent data monitoring process is used to support dose selection and cohort progression.
Part C (Multiple-Dose Expansion in HHT with Pulmonary Arterial Hypertension):
Part C evaluates the safety, tolerability, pharmacokinetics, and clinical effects of DIAG723 in a population of patients with HHT and concomitant pulmonary arterial hypertension. Participants are randomized to receive DIAG723 or placebo and receive the same general multiple-dose treatment approach as in Part B. Dose selection for Part C is informed by cumulative data from Part A and Part B, with additional assessments conducted to characterize effects in this specific patient population.
Across all study parts, participants are randomized using an interactive response system, and study treatment is administered under double-blind conditions. A Safety Review Committee and an independent Data Safety Monitoring Board provide ongoing review of safety data and support dose-escalation and progression decisions throughout the study. Dose escalation and cohort progression are guided by predefined safety criteria and overall risk-benefit assessment.
All doses are administered by subcutaneous injection, and participants undergo safety monitoring, pharmacokinetic sampling, and clinical assessments at scheduled study visits. The study includes both inpatient and outpatient components depending on the study part and stage of participation.
This study is designed to characterize the safety profile and pharmacokinetic properties of DIAG723 and to support selection of appropriate doses and regimens for further clinical development in HHT.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, care provider, investigator)
- Number of arms
- 2
- Model description
- This is a 3-part sequential study (Parts A, B, and C) with separate randomization within each part
| Arm | Type | Receives |
|---|---|---|
| DIAG723 | Experimental | Biological: DIAG723Participants 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 | Other: PlaceboParticipants 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). |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- 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
Key exclusion criteria (5 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| DIAG723Bispecific 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 | Biological | DIAG723 |
| PlaceboSterile normal saline (0.9% NaCl) administered subcutaneously in volumes matched to DIAG723 to maintain study blinding. | Other | Placebo Comparator |
Primary outcome
Incidence of Treatment-Emergent Adverse Events (TEAEs) - Part A (Single Dose)
Time frame: From first dose through Day 28
Number and proportion of participants experiencing TEAEs following single-dose administration of DIAG723.
Incidence of Serious Adverse Events (SAEs) - Part A (Single Dose)
Time frame: From first dose through Day 28
Number and proportion of participants experiencing SAEs following single-dose administration of DIAG723.
Incidence of Dose-Limiting Toxicities (DLTs) - Part A (Single Dose)
Time frame: From first dose through Day 28
Number and proportion of participants experiencing DLTs during the dose-escalation period following single-dose administration.
Number of participants with abnormal laboratory tests results - Part A (Single Dose)
Time frame: Baseline through Day 28
Laboratory assessments include hematology (complete blood count), clinical chemistry (basic metabolic panel; liver function tests; renal function; electrolytes; thyroid-stimulating hormone, free T4, free T3; cortisol; luteinizing hormone; lipase; amylase), coagulation (prothrombin time/international normalized ratio, activated partial thromboplastin time), and urinalysis.
Number of participants with abnormal vital signs - Part A (Single Dose)
Time frame: Baseline through Day 28
Vital sign measurements include body temperature, heart rate, respiratory rate, blood pressure, and oxygen saturation.
Change from Baseline in Electrocardiogram (ECG) Parameters - Part A (Single Dose)
Time frame: Baseline through Day 28
Change from baseline in ECG parameters, including QTc interval.
Incidence of Treatment-Emergent Adverse Events (TEAEs) - Part B (Multiple Dose)
Time frame: From first dose through 28 days after final dose
Number and proportion of participants experiencing TEAEs following multiple-dose administration of DIAG723.
Incidence of Serious Adverse Events (SAEs) - Part B (Multiple Dose)
Time frame: From first dose through 28 days after final dose
Number and proportion of participants experiencing SAEs following multiple-dose administration.
Incidence of Dose-Limiting Toxicities (DLTs) - Part B (Multiple Dose)
Time frame: From first dose through 28 days after final dose
Number and proportion of participants experiencing DLTs during multiple-dose treatment.
Number of participants with abnormal laboratory tests results - Part B (Multiple Dose)
Time frame: Baseline through Week 15
Laboratory assessments include hematology (complete blood count), clinical chemistry (basic metabolic panel; liver function tests; renal function; electrolytes; thyroid-stimulating hormone, free T4, free T3; cortisol; luteinizing hormone; lipase; amylase), coagulation (prothrombin time/international normalized ratio, activated partial thromboplastin time), and urinalysis.
Number of participants with abnormal vital signs - Part B (Multiple Dose)
Time frame: Baseline through Week 17
Vital sign measurements include body temperature, heart rate, respiratory rate, blood pressure, and oxygen saturation.
Change from Baseline in Electrocardiogram (ECG) Parameters - Part B (Multiple Dose)
Time frame: Baseline through Week 17
Change from baseline in ECG parameters, including QTc interval.
Incidence of Treatment-Emergent Adverse Events (TEAEs) - Part C (Multiple Dose, HHT with PAH)
Time frame: From first dose through 28 days after final dose
Number and proportion of participants experiencing TEAEs following multiple-dose administration in participants with HHT and pulmonary arterial hypertension.
Incidence of Serious Adverse Events (SAEs) - Part C (Multiple Dose, HHT with PAH)
Time frame: From first dose through 28 days after final dose
Number and proportion of participants experiencing SAEs in this population.
Incidence of Dose-Limiting Toxicities (DLTs) - Part C (Multiple Dose, HHT with PAH)
Time frame: From first dose through 28 days after final dose
Number and proportion of participants experiencing DLTs during treatment.
Number of participants with abnormal laboratory tests results - Part C (Multiple Dose, HHT with PAH)
Time frame: Baseline through Week 15
Laboratory assessments include hematology (complete blood count), clinical chemistry (basic metabolic panel; liver function tests; renal function; electrolytes; thyroid-stimulating hormone, free T4, free T3; cortisol; luteinizing hormone; lipase; amylase), coagulation (prothrombin time/international normalized ratio, activated partial thromboplastin time), and urinalysis.
Number of participants with abnormal vital signs - Part C (Multiple Dose, HHT with PAH)
Time frame: Baseline through Week 17
Vital sign measurements include body temperature, heart rate, respiratory rate, blood pressure, and oxygen saturation.
Change from Baseline in Electrocardiogram (ECG) Parameters - Part C (Multiple Dose, HHT with PAH)
Time frame: Baseline through Week 17
Change from baseline in ECG parameters, including QTc interval.
20 secondary outcomes
Area Under the Plasma Concentration-Time Curve (AUC) of DIAG723 - Part A
Time frame: Pre-dose through Day 28
Maximum Observed Plasma Concentration (Cmax) of DIAG723 - Part A
Time frame: Pre-dose through Day 28
Time to Maximum Plasma Concentration (Tmax) of DIAG723 - Part A
Time frame: Pre-dose through Day 28
Area Under the Plasma Concentration-Time Curve (AUC) of DIAG723 - Part B (Multiple Dose)
Time frame: Pre-dose through 28 days after final dose
Maximum Observed Plasma Concentration (Cmax) of DIAG723 - Part B (Multiple Dose)
Time frame: Pre-dose through 28 days after final dose
Time to Maximum Plasma Concentration (Tmax) of DIAG723 - Part B (Multiple Dose)
Time frame: Pre-dose through 28 days after final dose
Incidence of Anti-Drug Antibodies (ADA) to DIAG723 - Part A (Single Dose)
Time frame: From first dose through Day 28
Incidence of Anti-Drug Antibodies (ADA) to DIAG723 - Part B (Multiple Dose)
Time frame: From first dose through 28 days after final dose
Change from Baseline in Epistaxis Frequency - Part B (Multiple Dose)
Time frame: Baseline through end of treatment (13 weeks)
Change from Baseline in Epistaxis Flow Intensity, Duration, and Intensity-Adjusted Duration - Part B (Multiple Dose)
Time frame: Baseline through end of treatment (13 weeks)
Change from Baseline in Hemoglobin - Part B (Multiple Dose)
Time frame: Baseline through Week 15
Change from Baseline in Hematocrit - Part B (Multiple Dose)
Time frame: Baseline through Week 15
Change in Mean Corpuscular Volume (MCV) Following Multi-dose Treatment With DIAG723 (Part B)
Time frame: Baseline through Week 15
Change from Baseline in Red Blood Cell Count Following Multi-dose Treatment With DIAG723
Time frame: Baseline through Week 15
Change from Baseline in White Blood Cell Count Following Multi-dose Treatment With DIAG723 (Part B)
Time frame: Baseline through Week 15
Change from Baseline in Platelet Count Following Multi-dose Treatment With DIAG723 (Part B)
Time frame: Baseline through Week 15
Change in Red Blood Cell (RBC) Units Transfused During Treatment With DIAG723 (Part B)
Time frame: Baseline through Week 15
Change in Elemental Iron Infused During Treatment With DIAG723 (Part B)
Time frame: Baseline through Week 15
Change in Hematologic Support Score (HSS) Following Treatment With DIAG723 (Part B)
Time frame: Baseline through Week 17
Change in Hematologic Impact Score (HIS) Following Treatment With DIAG723 (Part B)
Time frame: Baseline through Week 17
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 8 Sep 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
11 sites in 3 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1/2 study testing DIAG723 in people with Hereditary Hemorrhagic Telangiectasia and Pulmonary Arterial Hypertension, run by Diagonal Therapeutics, Inc. at 11 sites in 3 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 8 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 11 sites in Australia, Canada, New Zealand. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Diagonal Therapeutics (339-233-4291, clinicalinfo@diagonaltx.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Incidence of Treatment-Emergent Adverse Events (TEAEs) - Part A (Single Dose) (time frame: From first dose through Day 28). The study lists 18 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 8 Sep 2026.