Medialis differentiated GSK- ERA within the Endothelin Receptor Antagonist Class

Pulmonary arterial hypertension (PAH) is a disorder primarily of small pulmonary arteries which results in a progressive rise in pulmonary vascular resistance and right ventricular failure. It consists of 4 classes of increasing severity relating to exercise tolerance.


The endothelin receptor class of medicines is used to treat class II and III PAH. Following the withdrawal of the Pfizer- ERA, 2 remained in this class: GSK- ERA & Actelion- ERA. Initial differentiation was based around a reduced incidence of drug-drug interaction & reduced Liver Function test abnormalities on treatment. The assumption here was that differentiation could only be on the basis of safety profile and not on efficacy.

Questions still remained as to whether there was any difference in expected improvement in exercise tolerance, measured in studies using the 60-minute walk test.


Informal review of randomised placebo-controlled trials with GSK-ERA and Actelion-ERA suggested a statistically significant difference in improvement in a 6-minute walk test would be unlikely given the nature of the disease and the small populations examined. However, clinicians in the therapy area were still willing to accept clinically meaningful differences and were familiar with this as a concept. Various strategies were considered in meeting this need for evidence.

Asset generation

A mixed treatment comparison and meta analysis were carried out with the focus on the primary outcome of improvement in a 6-minute walk test efficacy measure.

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