The aim of the study is to investigate whether the cells which line the blood vessels (called "endothelial cells") are involved in the processes which contribute to Pulmonary Arterial Hypertension (PAH). PAH is a rare condition in which a narrowing of blood vessels carrying blood through the lungs puts an increased workload on the heart; it has to work harder to pump blood through the lungs. Previous studies have shown that these "endothelial cells" may be involved in causing this narrowing. We have shown that a particular protein (called TSPO) which is present on these cells, might be involved in this process. The purpose of the study is to use a drug (called XBD173) which targets TSPO, in order to learn how it affects endothelial cells and the blood vessels. Patients will be invited to participate by their local pulmonary hypertension hospital. Participants will be treated with XBD173 (180mg daily, in three divided doses of 60mg). The total period of treatment for each patient is 6 weeks, followed by 4 weeks follow up off XBD173. If a patient does not tolerate the XBD173 the local PI will determine whether to stop XBD173, reduce the dose to 60mg OD or BD, or pause dosing and restart at 60mg OD or BD. Participants will undergo an echocardiogram and an 18-FDG PET scan of the heart and lung before and after the intervention period. Doses of 180mg per day (in two doses of 90mg) have been well tolerated in patients with cerebral small vessel disease in another ongoing study (IRAS 339664). The proposed study will recruit patients with PAH attending specialist clinics that have an approved implanted cardiopulmonary monitor (CardioMEMSTM Heart Failure system) that permits remote sensing. The monitor will have been implanted on clinical grounds. Patients with stable readings for at least a month will be considered for recruitment. These stable readings provide a good baseline from which to measure the effect of the study drug and relate to changes in blood biomarkers. Remote sensing offers greater oversight of the patient and closer safety monitoring. Remotely acquired patient data are reviewed twice a week via a central clinical team based in Sheffield. Relevant data will be shared as de-identifiable information, and sent to Imperial College London (upon request) as pseudonymised (coded) data if there are any concerns regarding patients' safety. Follow-up would be scheduled by telephone or video conferencing with hospital visits being optional. The most common side effects reported with XBD173 include nervous system and gastrointestinal symptoms, but the frequencies of these side effects are no higher than placebo. The end of the study will be the last visit of the last subject.
Age range
18 Years – 75 Years
Sex
ALL
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To determine whether changes in endothelial cell dysfunction are associated with changes in total pulmonary resistance in patients with pulmonary arterial hypertension
Timeframe: By week 6
To determine whether changes in endothelial cell dysfunction are associated with changes in total pulmonary resistance in patients with pulmonary arterial hypertension
Timeframe: By week 6