Phase 4 Trial Shows Opsumit Can Improve Ventricle Function for Pulmonary Arterial Hypertension Patients

A recent Phase 4 study has shown that Opsumit can improve function of the right heart ventricle for patients with pulmonary arterial hypertension (PAH). The right ventricle pumps blood to the lungs, while the left pumps blood out of the heart and to the rest of the body. Together, these ventricles make up the hearts lower chambers.

Opsumit is already approved as an oral treatment which can sooth symptoms and slow disease progression. This treatment works by widening and relaxing the blood vessels, which lowers the patient’s blood pressure.


The REPAIR trial was a phase 4, multi-center and open-label investigation run by Actelion. It included 87 PAH patients who were symptomatic. Initial measurements were recorded at week 26 but patients remained on the therapy for 52 weeks in total.

The REPAIR trial was the very first trial to specifically examine RVSV (RV stroke volume) as its primary endpoint (through an MRI). This is a measure of the total amount of blood that is ejected from the heart’s right ventricle each time it contracts. Essentially, this study was examining what effects this treatment could have on the function and blood flow of the right ventricle. This is an important inquiry because right ventricle dysfunction can be a sign that PAH is progressing.

However, this wasn’t the only thing measured in this trial. Also investigated were any changes to the patients’ pulmonary vascular resistance, which is a measure for the strain the heart is undergoing. Additionally, the capacity volume of the right ventricle, exercise capacity, and their WHO functional class (measuring disease severity) was recorded.


For 39% of trial participants their first ever PAH treatment was through this trial. These individuals were given both Opsumit as well as a vasodilator compound. Another 25% had never been on another therapy but were only given Opsumit. 36% of patients had already been taking a vasodilator compound and their only new addition was Opsumit.

Results were documented for 71 patients. By week 26 there was a,

  • 12mL increase of RVSV
  • 38% decrease of pulmonary vascular resistance
  • Improvement in ventricle cavity volume
  • Improvement in ventricle mass
  • Improvement in exercise capacity
  • 56.3% of participants moved to a milder WHO class
  • No patient moved to a worse WHO class
  • The same safety and tolerability data as previous investigations were recorded

Further, the improvements in exercise capacity scores and RVSV at the 26th week were maintained until the trials conclusion at week 52.

These findings are important as it is known that deterioration of the right ventricle is one of the most severe results of PAH. Researchers contend the results from the REPAIR trial show that either by itself, or combined with other therapies, Opsumit can benefit patients.

You can read more about this trial and findings here.

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