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Withdrawal of Prostacyclin Pathway Therapy in Patients With Pulmonary Arterial Hypertension Receiving Sotatercept (WATERLOO)

Withdrawal of Background Prostacyclin Pathway Therapy in Patients With Pulmonary Arterial Hypertension Receiving Sotatercept: an Open Label Non-inferiority Trial

Status
Not yet recruiting
Phases
Unknown
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT07700303
Acronym
WATERLOO
Enrollment
78
Registered
2026-07-14
Start date
2026-09-30
Completion date
2030-03-30
Last updated
2026-07-15

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Pulmonary Arterial Hypertension

Keywords

Prostacyclin, sotatercept, open label, non-inferiority, Weatherald, Canadian VIGOUR Centre, CVC, pulmonary arterial hypertension

Brief summary

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.

Interventions

PROCEDUREDiscontinuation of parenteral prostacyclins analogues or selexipag

Discontinuation of parenteral prostacyclins analogues or selexipag

Sponsors

University of Alberta
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

In order to be eligible for this study, a participant must meet all of the following criteria: 1. Adults ≥ 18 years old diagnosed with PAH. 2. Treatment with sotatercept for ≥6 months. 3. Background therapy with ≥2 PAH vasodilator therapies, one of which is a parenteral prostacyclin or selexipag. 4. At low or intermediate-low risk, defined using the 2022 ESC/ERS guidelines 4-strata risk assessment tool (Table 1). 5. RHC at screening or historical within 8 weeks of screening, and after at least 6 months of sotatercept treatment, demonstrating a mPAP ≤40 mmHg and PVR ≤5 WU 6. The ability to adhere to the study visit schedule and to comprehend and comply with all protocol requirements. 7. Ability to provide informed consent.

Exclusion criteria

A potential participant who meets any of the following criteria will be excluded from participation in this study: 1. Known intolerance to sotatercept 2. A RHC at screening or historical within 8 weeks of screening and after ≥6 months of sotatercept treatment demonstrating mPAP \> 40 mmHg or PVR \> 5 WU. 3. Hospitalization for worsening PAH or right heart failure within the 3 months prior to screening. 4. Active listing for lung or heart/lung transplantation. 5. Metastatic cancer or any other condition with a life expectancy \< 6 months, 6. Female patients who are pregnant or who are of childbearing age and are unwilling to use contraception during the study. 7. History of ≥ 3 interruptions or missed doses of sotatercept for any reason within the previous 6 months prior to screening. 8. Patients who received any investigational medication within 1 month prior to screening (unless known to be placebo) or who are scheduled to receive another investigational drug during the course of this study.

Design outcomes

Primary

MeasureTime frameDescription
Change in Mean Pulmonary Arterial Pressure (mPAP) From Baseline to 24 WeeksBaseline to 24 weeksDifference 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.

Secondary

MeasureTime frameDescription
Time to First Occurrence of All-Cause Death or Clinical WorseningBaseline to 24 weeksComparison 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.
Change in EmPHasis-10 Score From Baseline to Week 24Baseline to 24 weeksDifference 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.
Change in EQ-5D-5L Index Score From Baseline to Week 24Baseline to Week 24Difference 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.
Change in EQ Visual Analogue Scale (EQ VAS) Score From Baseline to Week 24Baseline to Week 24Difference 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.
Change in Living with Medicines Questionnaire Version 3 (LMQ-3) Score From Baseline to Week 24Baseline to Week 24Difference 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.
Number of Participants Reporting Prostanoid-Associated Side EffectsBaseline to 24 weeksDifference 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.

Countries

Canada

Contacts

CONTACTCanadian VIGOUR Centre Clinical Trial Project Lead
waterloo@ualberta.ca1-800-707-9098
PRINCIPAL_INVESTIGATORDr. Jason Weatherald, MD, MSc, FRCPC

University of Alberta

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Jul 16, 2026