NCT07700303Not yet recruiting
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
Source: ClinicalTrials.gov · Last updated 23 Sept 2026
Brief summary (registry, in English)
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.
- Status (registry)
- Not yet recruiting
- Study type
- Interventional
- Enrollment
- 78 (estimated)
- First submitted
- 15 Jun 2026
- Start date
- Oct 2026
- Primary completion date
- Mar 2028
- Lead sponsor
- University of Alberta
- NCT number
- NCT07700303
What you commit to
- Study type: Interventional
- Planned participants: 78
- From Oct 2026 to the primary completion date, Mar 2028
- 1 site in 1 country
- Visits and tests: ask the trial team, the registry does not list them
Built from the registry fields of ClinicalTrials.gov. It describes the study, not your situation.
Who cannot take part
Copied verbatim from ClinicalTrials.gov and grouped by topic. Only the trial team decides who can take part.
Prior treatment
- Hospitalization for worsening PAH or right heart failure within the 3 months prior to screening.
- History of ≥ 3 interruptions or missed doses of sotatercept for any reason within the previous 6 months prior to screening.
- 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.
Other illness
- Active listing for lung or heart/lung transplantation.
- Metastatic cancer or any other condition with a life expectancy \< 6 months,
Age
- Female patients who are pregnant or who are of childbearing age and are unwilling to use contraception during the study.
Other
- Known intolerance to sotatercept
- 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.
Who the study is looking for
- Adults ≥ 18 years old diagnosed with PAH.
- Treatment with sotatercept for ≥6 months.
- Background therapy with ≥2 PAH vasodilator therapies, one of which is a parenteral prostacyclin or selexipag.
- At low or intermediate-low risk, defined using the 2022 ESC/ERS guidelines 4-strata risk assessment tool (Table 1).
- 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
- The ability to adhere to the study visit schedule and to comprehend and comply with all protocol requirements.
- Ability to provide informed consent.
Age in the registry: 18 years to - · Sex: All · Does not accept healthy volunteers
Sites (1)
Sites in registry order. Pick your city on the disease page to sort them by distance.
| Site | City | Country | Site status |
|---|---|---|---|
| University of Alberta Hospital Coordinator of this site? Confirm its status | Edmonton | Canada | Unknown status |
This page is information, not medical advice. Discuss any trial with your doctor.