Merck & Co – known as MSD outside the US and Canada – has announced positive topline results from a phase 3 trial of sotatercept as an add-on to stable background therapy for the treatment of pulmonary arterial hypertension (PAH).
PAH is a rare, progressive and life-threatening blood vessel disorder characterised by the constriction of small pulmonary arteries and elevated blood pressure in the pulmonary circulation, resulting in a significant strain on the heart.
Currently, an estimated 40,000 people in the US and 30,000 people in the EU are living with PAH and the disease progresses rapidly for many patients despite current standard-of-care treatment, with the five-year mortality rate for patients with PAH approximately 43%.
The phase 3 STELLAR trial is a randomised double-blind, placebo-controlled, multicentre, parallel-group study designed to evaluate the safety and efficacy of sotatercept, an investigational activin receptor type IIA-Fc fusion protein, compared to placebo.
The study met its primary efficacy outcome measure, demonstrating a statistically significant and clinically meaningful improvement in six-minute walk distance from baseline at 24 weeks.
Moreover, eight of nine secondary efficacy outcome measures achieved statistical significance, including the outcome measure of proportion of participants achieving multicomponent improvement, as well as the outcome measure of time to death or the first occurrence of a clinical worsening event.
The overall safety profile of sotatercept in the study was generally consistent with what has been observed in phase 2, the company reported.
Sotatercept has been granted Breakthrough Therapy designation by the US Food and Drug Administration, as well as Priority Medicines designation by the European Medicines Agency for the treatment of PAH.
Commenting on the positive results, Dr Dean Li, president, Merck Research Laboratories, said: “In the phase 3 STELLAR study, sotatercept added to currently approved background therapy showed a profound effect on the primary efficacy outcome measure of improvement from baseline to 24 weeks in six-minute walk distance. The results from the secondary efficacy outcomes, including a favourable benefit seen in patients’ time to a clinical-worsening event, are especially noteworthy.
“We believe that in totality, the results observed in the STELLAR study suggest that sotatercept has the potential to transform the treatment of patients with PAH. We are moving with urgency on our regulatory applications to bring this investigational therapy to these patients.”