An interventional study of Discontinuation of parenteral prostacyclins analogues or selexipag in Pulmonary Arterial Hypertension, sponsored by University of Alberta. Not yet recruiting at 1 site in Canada. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-23.
Sponsored by University of Alberta · Not applicable, Interventional, and Treatment
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Among 85 studies in Pulmonary Arterial Hypertension with a site in Canada — 8 open to participants now, 12 under way, 5 of them phase 3. Pulmonary Arterial Hypertension · Canada.
Among the 85 studies in Pulmonary Arterial Hypertension with a site in Canada, this one is the 48th largest by planned enrollment of the 78 interventional ones that give a count, is one of 3 that started in 2026, is one of 6 with no phase, reaches primary completion later than 7 of the 11 other live ones, and was the 85th registered.
699 studies on the registry are indexed under Pulmonary Arterial Hypertension; 140 are open to participants now.
Browse Pulmonary Arterial Hypertension studies →8 of the 85 studies in Pulmonary Arterial Hypertension with a site in Canada are open now. Recruiting first, the newest first:
Diagonal Therapeutics, Inc. · Sites in Canada, Australia, New Zealand
Ages 18+
Inhibikase Therapeutics · Sites in Canada, United States, Argentina and 11 more countries
Ages 18–75
AllRock Bio, Inc. · Sites in Canada, United States, Australia and 6 more countries
Ages 18–80
Gossamer Bio USA, Inc. · Sites in Canada, United States, Argentina and 27 more countries
Ages 18–75
Duke University · Sites in Canada, United States
Ages 0–20 · Healthy volunteers
A study can be open while its sites in Canada have not opened yet or have stopped. Only those recruiting at a site in Canada →
Of the 90 Pulmonary Arterial Hypertension studies recruiting now, 51 (57%) set no upper age limit and 24 (27%) stop at 75 or younger; 18 take children under 18; 11 take healthy volunteers.
This study: 18 Years and older · all sexes · no healthy volunteers.
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85 studies; the count open now beside each. This study's row is marked.
A study in two phases is counted once above. Listed by phase, each with its combined phases: Phase 1 9 · Phase 2 20 · Phase 3 42 · Phase 4 7
First in 2003; this study’s year is marked. 3 started in 2026.
By drug class, each counting the studies that test any of its medicines:
This study's planned enrollment of 78 is above the median of 40 across 477 interventional studies indexed under Pulmonary Arterial Hypertension.
Median enrollment 163 across the 78 interventional studies, 490 across the 7 observational. Of the 66 that completed or were terminated, 39 (59%) have results posted.
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65 of 85 have an industry lead sponsor. The 10 most frequent:
University of Alberta is the lead sponsor of 824 studies on the registry; 171 are open to participants now.
Of its 5 completed or terminated interventional studies of FDA-regulated products, 3 (60%) have results posted.
University of Alberta has 2 studies filed under Pulmonary Arterial Hypertension — fewer than ten, so there is no comparison to draw.
5 of the studies in Pulmonary Arterial Hypertension with a site in Canada that are under way reach primary completion within a year, 2 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT03683186Phase 3United TherapeuticsA Study Evaluating the Long-Term Efficacy and Safety of Ralinepag in Subjects With PAH Via an Open-Label Extension | 2026-12 |
| NCT06274801Phase 3Gossamer Bio USA, Inc.Open-label Extension Study of Seralutinib in Adult Subjects With PAH (PROSERA-EXT) | 2026-12 |
| NCT04278404Duke UniversityPharmacokinetics, Pharmacodynamics, and Safety Profile of Understudied Drugs Administered to Children Per Standard of Care (POPS) | 2026-11 |
| NCT07175038AllRock Bio, Inc.A Study of ROC-101 in Patients With Pulmonary Arterial Hypertension (PAH) and Pulmonary Hypertension Associated With Interstitial Lung Disease (ILD-PH) (ROCSTAR STUDY) | 2027-03 |
| NCT07623525Diagonal Therapeutics, Inc.DIAG723 in Adults With Hereditary Hemorrhagic Telangiectasia | 2027-11-30 |
Add all 5 to your calendar (.ics) → With an account.
Among the 85 studies in Pulmonary Arterial Hypertension with a site in Canada, from their registry updates:
Nothing recorded among them since 2026-09-25.
This tab as a report to print or save as PDF → With an account.
Pulmonary arterial hypertension (PAH) is a rare lung disease that leads to elevated blood pressure in the lungs and strain on the right side of the heart. For many years, treatments for PAH have included drugs that target the prostacyclin pathway using intravenous, subcutaneous, oral, and inhaled drugs. These drugs help widen the blood vessels in the lungs so the heart does not have to work as hard. However, these medicines can cause side effects such as jaw pain, flushing, diarrhea, and nausea, and the pump therapy can be very hard to manage day-to-day.
A newer medicine called sotatercept works in a different way. It helps fix some of the root causes of PAH. Early reports suggest that some people do very well on sotatercept and may not need to keep taking their prostacyclin therapy. However, investigators do not yet know if it is safe to stop prostacyclin therapies or how to do so. This study, called WATERLOO, is designed to find out whether slowly stopping prostacyclin therapy while the participant is doing well on sotatercept is safe. Investigators will compare people who stop their prostacyclin therapy to people who keep taking it. This study is being done at PAH expert centres in Canada and Europe.
Inclusion Criteria: In order to be eligible for this study, a participant must meet all of the following criteria:
Exclusion Criteria: A potential participant who meets any of the following criteria will be excluded from participation in this study:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The control group will continue prostacyclin pathway therapies as per their authorized indications, with no change in dosage.
Dose de-escalation and discontinuation of parenteral prostacyclins analogues or selexipag
Procedure: Discontinuation of parenteral prostacyclins analogues or selexipag
Discontinuation of parenteral prostacyclins analogues or selexipag
Change in Mean Pulmonary Arterial Pressure (mPAP) From Baseline to 24 Weeks
Difference between the prostacyclin pathway therapy withdrawal group and the continuation group in the change in mean pulmonary arterial pressure (mPAP), measured in mmHg, from baseline to Week 24 by right heart catheterization.
Time frame: Baseline to 24 weeks
Time to First Occurrence of All-Cause Death or Clinical Worsening
Comparison between the prostacyclin pathway therapy withdrawal group and the continuation group in the time to first occurrence of the composite endpoint of all-cause death or clinical worsening. Clinical worsening is defined as any of the following: hospitalization for worsening PAH, decline in 6-minute walk distance (6MWD) ≥10% from baseline on two consecutive tests at least 4 hours apart accompanied by worsening WHO functional class, or worsening ESC/ERS 4-strata risk status.
Time frame: Baseline to 24 weeks
Change in EmPHasis-10 Score From Baseline to Week 24
Difference between the prostacyclin pathway therapy withdrawal group and the continuation group in the change from baseline to Week 24 Unit of Measure: Score Range: 0-50 Higher scores indicate worse pulmonary hypertension-related quality of life.
Time frame: Baseline to 24 weeks
Change in EQ-5D-5L Index Score From Baseline to Week 24
Difference between the prostacyclin pathway therapy withdrawal group and the continuation group in the change from baseline to Week 24 in the EQ-5D-5L Index Score. Unit of Measure: Index score Country-specific value set; Higher scores indicate better health status.
Time frame: Baseline to Week 24
Change in EQ Visual Analogue Scale (EQ VAS) Score From Baseline to Week 24
Difference between the prostacyclin pathway therapy withdrawal group and the continuation group in the change from baseline to Week 24 in the EQ-5D-5L Index Score. Unit of Measure: score Range: 0-100 Higher scores indicate better perceived health.
Time frame: Baseline to Week 24
Change in Living with Medicines Questionnaire Version 3 (LMQ-3) Score From Baseline to Week 24
Difference between the prostacyclin pathway therapy withdrawal group and the continuation group in the change from baseline to Week 24 in the EQ-5D-5L Index Score. Unit of Measure: Score Range: 41-205 Higher scores indicate a greater medication burden.
Time frame: Baseline to Week 24
Number of Participants Reporting Prostanoid-Associated Side Effects
Difference between the prostacyclin pathway therapy withdrawal group and the continuation group in the number of participants reporting prostanoid-associated side effects, including jaw pain, flushing, nausea, diarrhea, and myalgia.
Time frame: Baseline to 24 weeks
Number of Participants Experiencing Adverse Events (AEs)
Difference between the prostacyclin pathway therapy withdrawal group and the continuation group in the number of participants experiencing one or more adverse events.
Time frame: Baseline to 24, 52 and 104 (End of Study) weeks
Number of Participants Experiencing Serious Adverse Events (SAEs)
Difference between the prostacyclin pathway therapy withdrawal group and the continuation group in the number of participants experiencing one or more serious adverse events.
Time frame: Baseline to 24, 52 and 104 (End of Study) weeks
Participant Enrollment Rate
Number of participants enrolled per site per month during the 24-week recruitment period.
Time frame: Baseline to 24 weeks
Protocol Adherence Rate
Proportion of participants who complete study procedures according to protocol through Week 24 without major protocol deviations.
Time frame: Baseline to Week 24
Completeness of Secondary and Exploratory Outcome Data
Proportion of expected secondary and exploratory outcome data points successfully collected through Week 24.
Time frame: Baseline to Week 24
Plan to share: Undecided
Start is estimated for Oct 2026; primary completion for Mar 2028, 17 months later.
Of 60 non-industry interventional studies with no phase under Pulmonary Arterial Hypertension, half reached primary completion within 44 months of starting (the median), counting those still running; a quarter within 18 and three quarters within 63. This study's planned 17 months is below that.
Counting every sponsor, half of 65 studies reached it within 42 months; a quarter within 18 and three quarters within 71.
How these figures are worked out, and which studies are left out of them.
This study is not yet recruiting, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
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Pulmonary Arterial Hypertension →