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Single Ventricle Heart DiseasePhase 3FUEL-2NCT05918211

Fontan Udenafil Exercise Longitudinal Assessment Trial - 2

A Phase 3 study testing Udenafil in people with Single Ventricle Heart Disease, run by Mezzion Pharma Co. Ltd at 40 sites in 2 countries.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

This study will evaluate the clinical efficacy and safety of udenafil, an orally administered, potent and selective inhibitor of PDE5, versus placebo for the treatment of adolescent who have had the Fontan procedure. Read more about this study

Who is it for?
Ages 12 to 18 years
Conditions the study is for
Single Ventricle Heart Disease
What is being tested?
Udenafil
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
436 participants
Where
40 sitesin 2 countries
Study dates
30 Oct 2023to 28 Oct 2025
Phase
Phase 3
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 12 to 18 years
  • All sexes
  • No healthy volunteers
  • Child, Adult

Who may be able to join

  • Males and females with Fontan physiology who are 12 to less than 19 years of age at enrollment.
  • Participant consent or parental/guardian consent and participant assent.
  • Participant fluency in primary language of country in which study is being conducted.
  • Current antiplatelet or anticoagulant therapy.

Who cannot join

  • Height < 132 cm.
  • Weight < 40 kg.
  • Hospitalization for acute decompensated heart failure within the last 12 months.
  • Current intravenous inotropic drugs.
  • Undergoing evaluation for heart transplantation or listed for transplantation.
  • Diagnosis of active protein losing enteropathy or plastic bronchitis within the last 3 years, or a history of liver cirrhosis.
Show all 30Show fewer
  • Known Fontan baffle obstruction, branch pulmonary artery stenosis, or pulmonary vein stenosis resulting in a mean gradient of > 4 mmHg between the regions proximal and distal to the obstruction as measured by either catheterization or echocardiography, obtained prior to screening for the trial.
  • Single lung physiology with greater than 80% flow to one lung.
  • Failure to achieve maximal exertion (defined as RER < 1.10) on screening/baseline exercise test.
  • Peak minute oxygen consumption (VO2) less than 45% or ≥ 80% of predicated for age and gender at enrollment.
  • Severe ventricular dysfunction assessed qualitatively by clinical echocardiography within 6 months prior to enrollment.
  • Severe valvar regurgitation, ventricular outflow obstruction, or severe aortic arch obstruction assessed by clinical echocardiography within six months prior to enrollment.
  • History of significant renal (serum creatinine > 2.0), hepatic (serum AST and/or ALT > 3 times upper limit of normal), gastrointestinal or biliary disorders that could impair absorption, metabolism or excretion of orally administered medications.
  • Inability to complete exercise testing at baseline screening.
  • Subjects with a pacemaker whose heart rate at peak exercise is controlled by the extrinsic pacemaker as opposed to a native atrial rhythm.
  • History of PDE-5 inhibitor use within 12 months prior to enrollment. (Treatment is defined as chronic therapy as opposed to a single dose.)
  • History of any other medication for treatment of pulmonary hypertension within 3 months before study onset.
  • Known intolerance to oral udenafil.
  • Frequent use of medications or other substances that inhibit or induce CYP3A4.
  • Current use of alpha-blockers or nitrates.
  • Ongoing or planned participation in another research protocol that would either prevent successful completion of planned study testing or invalidate its results.
  • Noncardiac medical, psychiatric, and/or social disorder that would prevent successful completion of planned study testing or would invalidate its results.
  • Cardiac care, ongoing or planned, at a non-study center that would impede study completion.
  • For females: Pregnancy at the time of screening, pregnancy planned before study completion, or refusal to use an acceptable method of contraception for study duration if sexually active.
  • Unable to abstain or limit intake of grapefruit juice and grapefruit containing drinks during the duration of the trial.
  • Refusal to provide written informed consent/assent.
  • In the opinion of the investigator, the subject is likely to be non-compliant with the study protocol.
  • History of clinically significant thromboembolic event, in the option of the site Principal Investigator, that may put the subject at increased risk of a subsequent event while participating in the study.
  • Coronavirus disease 2019 (COVID-19) vaccination or symptoms of COVID-19 infection within 7 days of Visit 1.
  • Not taking antiplatelet or anticoagulant therapy.

Trial locations and contacts

40 sites in 2 countries. Contact the study team or a site near you to ask about taking part.

WG Kim contact

443.699.6746

wgkim@mezzion.com

40 sites in 2 countries

United States37 sites, 37 recruiting

  • University of Michigan

    Ann Arbor, Michigan, 48109

    Cynthia Smith, 734-615-0590, csmithw@med.umich.edu

    Kurt Schumacher, MD

    Recruiting

  • Children's Healthcare of Atlanta

    Atlanta, Georgia, 30329

    Jessica Braun, 404-785-3828, jessica.braun@choa.org

    Michael Lopez, MD

    Recruiting

  • Children's Hospital of Georgia

    Augusta, Georgia, 30912

    Michelle Collins, 706-721-9680, MCOLLINS2@augusta.edu

    Mark Vranicar, MD

    Recruiting

  • Boston Children's Hospital

    Boston, Massachusetts, 02115

    Tom Giorgio, 617-355-4201, thomas.giorgio@cardio.chboston.org

    Rahul Rathod, MD

    Recruiting

  • MUSC Pediatric Research Group

    Charleston, South Carolina, 29425

    Susannah C Wakefield, 843-792-8317, wakefies@musc.edu

    Andrew Atz, MD

    Recruiting

  • Dana.Amaro@atriumhealth.org

    Charlotte, North Carolina, 28204

    Dana Amaro, 704-355-4692, dana.amaro@atriumhealth.org

    Matthew Schwartz, MD

    Not yet recruiting

  • Lurie Children's Hospital

    Chicago, Illinois, 60611

    Jessica Bhavsar, 312-227-4432, jbhavsar@luriechildrens.org

    Kendra Ward, MD

    Recruiting

  • University of Chicago

    Chicago, Illinois, 60637

    Becky Puplava, 773-702-2879, rpuplava@bsd.uchicago.edu

    Michael Earing, MD

    Recruiting

  • Cincinnati Childrens Hospital Medical Center

    Cincinnati, Ohio, 45206

    Mariah Palmer, 513-636-9516, Mariah.Palmer@cchmc.org

    Sasha Opotowsky, MD

    Recruiting

  • Cleveland Clinic

    Cleveland, Ohio, 44195

    Ewing Paige, 216-445-8798, ewingp@ccf.org

    Shahnawaz Amdani, MD

    Recruiting

  • Nationwide Children's Hospital

    Columbus, Ohio, 43215

    Victoria Shay, 614-355-5819, victoria.shay@nationwidechildrens.org

    Omar Khalid, MD

    Recruiting

  • UT Southwestern Medical Center

    Dallas, Texas, 75235

    Aruna Ayalasomayajula, 702-340-7830, aruna.ayalasomayajula@utsouthwestern.edu

    Matt Lemler, MD

    Recruiting

  • Children's Hospital of Colorado

    Denver, Colorado, 80045

    Andrea DeMarsh, 216-906-7931, andrea.demarsh@childrenscolorado.org

    Roni Jacobsen

    Recruiting

  • Duke University Medical Center

    Durham, North Carolina, 27710

    Alexi Pifer, alexis.pifer@duke.edu

    Melissa Harward, melissa.harward@duke.edu

    Recruiting

  • UF Health Shands Hospital

    Gainesville, Florida, 32608

    Dalia Lopez-Colon, 352-281-6723, dalylc@ufl.edu

    Dipankar Gupta, MD

    Recruiting

  • Joe DiMaggio Children's Hospital

    Hollywood, Florida, 33021

    Norma Barton, 954-265-4466, NBarton@mhs.net

    Melissa Diamond, MD

    Recruiting

  • Texas Children's Hospital

    Houston, Texas, 77030

    Sara Stephens, 832-826-5613, sara.stephens@bcm.edu

    Daniel Penny, MD

    Recruiting

  • Children's Mercy Hospital Kansas City

    Kansas City, Missouri, 64108

    Dara Watkins, 816-302-3633, djwatkins@cmh.org

    Jonathan B Wagner, MD

    Recruiting

  • Arkansas Children's

    Little Rock, Arkansas, 72202

    Wendy Haley, 501-364-2237, haleyw@archildren's.org

    Dala Zakaria, MD

    Recruiting

  • Children's Hospital of Los Angeles

    Los Angeles, California, 90027

    Matthew Dam, 323-361-7881, mdam@chla.usc.edu

    Jon Detterich, MD

    Recruiting

  • Children's Hospital of Wisconsin

    Milwaukee, Wisconsin, 53226

    Jennifer Yauck, 414-266-2325, jyauck@childrenswi.org

    Stephanie Handler, MD

    Recruiting

  • Vanderbilt University Medical Center

    Nashville, Tennessee, 37232

    Sherry Bowman, 615-936-0061, sherry.bowman@vumc.org

    Benjamin Frischhertz, MD

    Recruiting

  • Yale School of Medicine

    New Haven, Connecticut, 06510

    Amanda Catucci, 631-897-6722, amanda.catucci@yale.edu

    Meredith Leslie, MD

    Recruiting

  • Mt. Sinai Children's Hospital

    New York, New York, 10029

    Xueru Mu, 347-335-7148, xueru.mu@mssm.edu

    Neha Bansel, MD

    Not yet recruiting

  • New York-Presbyterian Children's Hospital

    New York, New York, 10032

    Katrina Golub, 212-342-1562, kg2697@cumc.columbia.edu

    Christopher Petit, MD

    Recruiting

  • University of Nebraska Children's Hospital and Medical Center

    Omaha, Nebraska, 68114

    Morgan Loeffelbein, 402-559-0681, mloeffelbein@unmc.edu

    Angela Yetman, MD

    Recruiting

  • Children's Hospital of Philadelphia

    Philadelphia, Pennsylvania, 19104

    Faith Alunni, 570-430-5058, alunnif@chop.edu

    Jon Edelson, MD

    Recruiting

  • Phoenix Children's Hospital

    Phoenix, Arizona, 85016

    Jade Porche, 602-933-6835, jporche@phoenixchildrens.com

    Arash Sabati, MD

    Recruiting

  • Children's Hospital of Pittsburgh

    Pittsburgh, Pennsylvania, 15224

    Niklas Gerhart, 412-692-6742, gerhartne4@upmc.edu

    Lauren Carlozzi, MD

    Recruiting

  • Primary Children's Medical Center

    Salt Lake City, Utah, 84113

    Andrea Dunn, 801-213-7609, andrea.dunn@hsc.utah.edu

    Richard Williams, MD

    Recruiting

  • Rady Children's Hospital

    San Diego, California, 92123

    Mark Abcede, 619-987-0650, mabcede1@rchsd.org

    Jessica Haley, MD

    Recruiting

  • UCSF Benioff Children's Hospital

    San Francisco, California, 94158

    Aisling Conneally, 510-600-2965, aisling.conneally@ucsf.edu

    Doaa Aly, MD

    Recruiting

  • Seattle Children's Hospital

    Seattle, Washington, 98105

    Ranjini Prakash, 206-987-2000, Ranjini.Prakash@seattlechildrens.org

    Matthew Files, MD

    Recruiting

  • Washington University

    St Louis, Missouri, 63130

    Mason Basler, 618-579-5674, basler@wustl.edu

    William Orr, MD

    Recruiting

  • Johns Hopkins All Children's Hospital

    St. Petersburg, Florida, 33701

    Lexie Dallas, 727-767-2465, adallas@jhmi.edu

    Jamie Decker, MD

    Recruiting

  • Childrens National Medical Center

    Washington D.C., District of Columbia, 20010

    Stacy Davenport, 240-547-9804, amatthews@childrensnational.org

    Sairah Khan, MD

    Recruiting

  • Nemours Children's Hospital

    Wilmington, Delaware, 19803

    Carol Prospero, 302-651-6686, carol.prospero@nemours.org

    Mark Cartoski, MD

    Recruiting

Other trials in United States

South Korea3 sites, 3 recruiting

  • Sejong General Hospital

    Bucheon-si, Gyeonggi-do, 14754

    Jiyeun Jeong, 010-9221-5114, seize86@naver.com

    Yubin Min, 032-340-1782, yubin0812@naver.com

    Recruiting

  • Seoul National University Children's Hospital

    Seoul, 03080

    Gowoon Choi, go9979@snu.ac.kr

    Gibeom Kim, MD

    Recruiting

  • Yonsei Severance Hospital

    Seoul, 03722

    Juwon Heo, jwheo92@yuhs.ac

    Saeyong Jung, MD

    Recruiting

Other trials in South Korea

About this study

Official title: Fontan Udenafil Exercise Longitudinal Assessment Trial (FUEL-2)

This study will evaluate the clinical efficacy and safety of udenafil, an orally administered, potent and selective inhibitor of PDE5, versus placebo for the treatment of adolescent who have had the Fontan procedure.

Read the detailed description

This study is a 26 week, prospective, multicenter, randomized, double-blinded, placebo-controlled safety and efficacy study of udenafil vs. placebo in adolescent subjects who have had the Fontan procedure. The primary efficacy endpoint will be change from baseline at 26 weeks in peak minute oxygen consumption (VO2 mL/kg/min) as measured by maximal cardiopulmonary exercise test (CPET) reading laboratory who will be blinded to treatment allocation.

Being tested
Udenafil, Placebo
Keywords
Fontan, Maximal Oxygen Consumption, Work Rate, VO2 at VAT, Ventilatory Efficiency

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • UdenafilDrug

    Active drug

  • PlaceboDrug

    Matching Placebo

Study groups in NCT05918211
Study groupRoleWhat they receive
DrugExperimentalApproximately 218 subjects dosed with udenafil will be enrolled at approximately 30 sites.
Receives: Drug: Udenafil
PlaceboExperimentalApproximately 218 subjects dosed with matching placebo will be enrolled at approximately 30 sites.
Receives: Drug: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Change in Exercise Capacity

    The change in exercise capacity (as measured by maximal VO2 at maximum exercise effort) from baseline to 26 weeks (or study completion)

    Measured: Baseline to 26 Weeks

Secondary outcomes (4)

  1. Change in VO2 at the ventilatory anaerobic threshold (VAT)

    Change in peak oxygen consumption (VO2) from baseline to Week 26 as measured by maximal central cardiopulmonary exercise test (CPET) reading laboratory.

    Measured: Baseline to 26 weeks

  2. Change in Enhanced Liver Fibrosis (ELF) Score

    Change from baseline to Week 26 in the Enhanced Liver Fibrosis (ELF) Score calculated by the change in the following biomarkers: hyaluronic acid, amino-terminal propeptide of type III collagen, and tissue inhibitor of metalloproteinase-1. subjects with scores of <7.7 were assigned to the no or mild fibrosis group; 7.7 to 9.8 to the moderate fibrosis group, and >9.8 to the severe fibrosis group.

    Measured: Baseline to 26 weeks

  3. Work rate (watts) at ventilatory anaerobic threshold (VAT)

    Change from baseline to 26 weeks in work rate in watts at the ventilatory anaerobic threshold as measured by the central cardiopulmonary exercise test reading laboratory.

    Measured: Baseline to 26 weeks

  4. Change in ventilatory efficiency (VE/VCO2) at ventilatory anaerobic threshold

    Change from baseline to Week 26 in ventilatory efficiency calculated by ventilatory efficiency divided by minute carbon dioxide production at the ventilatory anaerobic threshold (VE/VCO2 at VAT).

    Measured: Baseline to 26 weeks

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted26 Jun 2023
  2. Study start30 Oct 2023
  3. Primary completion28 Oct 2025 (estimated)
  4. Study completion28 Oct 2025 (estimated)

Resources

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 3
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Model description
Randomized, double-blind, placebo-controlled safety and efficacy study of udenafil versus placebo of approximately 436 subjects enrolled equally between the two arms (udenafil and placebo)
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
436 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT05918211
Sponsor's protocol ID
MZ_Udenafil-05
Acronym
FUEL-2
Status last verified
Oct 2025
First submitted
15 Jun 2023
Last updated
28 Oct 2025
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
No

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing Udenafil in people with Single Ventricle Heart Disease, run by Mezzion Pharma Co. Ltd at 40 sites in 2 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 30 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 28 Oct 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 40 sites in United States, South Korea. 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. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

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 WG Kim (443.699.6746, wgkim@mezzion.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Change in Exercise Capacity (time frame: Baseline to 26 Weeks). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT05918211.

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 28 Oct 2025; AzTrials last refreshed its copy on 6 Nov 2026.

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