Data Presented on Sotatercept, a PAH Treatment

According to Biospace, Acceleron Pharma has presented preliminary data from their ongoing Phase 2 trial of sotatercept, a treatment for pulmonary arterial hypertension (PAH). The study, titled SPECTRA, is designed to evaluate hemodynamics and oxygen uptake.

About PAH

PAH is a form of high blood pressure that causes the pulmonary arteries of the lungs to progressively thicken and harden. The heart then has to work harder to get blood to the lungs, which can result in damage and possibly failure. Symptoms may not appear until there has been considerable progression, but when they do appear they include fainting, shortness of breath, dizziness, fatigue, chest pain, and swelling in the ankles and legs. These are caused by a mutated BMPR2, which plays a role in the growth and death of cells. It is passed down in an autosomal dominant pattern. In cases of secondary hypertension, the cause is another disease or the use of certain street drugs.


This trial is single-arm, exploratory, multi-center, and open-label, designed to investigate the effects of sotatercept in combination with the standard of care in adults with PAH that has been categorized as Class III by the World Health Organization. The primary endpoint is change from baseline in peak oxygen uptake after 24 weeks of treatment. This will be evaluated with invasive cardiopulmonary exercise testing. Secondary endpoints include exercise tolerance and capacity, cardiac index, ventilatory efficiency, hemodynamics, right heart catheterization, pulmonary vascular resistance, and more.

25 patients have enrolled, and their dosages will begin at 0.3 mg/kg for one cycle, followed by 0.7 mg/kg for the rest of the treatment period, which will last for six months. Participants are also welcome to take part in the 18 month extension study.

The Data Presented

Researchers witnessed improvements in hemodynamic measures, exercise tolerance, and exercise capacity. The largest hemodynamic improvement was pulmonary vascular resistance, which was reduced by 35.9%. Mean pulmonary arterial pressure was also greatly reduced, as it was lowered by 29.5%.

While results are still being gathered, participants in the trial have already experienced benefits. For example, one woman entered the trial with PAH that was considered Class III and left with PAH categorized as Class I. She saw significant improvements in hemodynamics and function.

In addition, minimal adverse events were seen. Any that were present remained consistent with data that has already been published on PAH. This is very exciting, as pulmonary arterial hypertension is a condition that requires more treatment options.

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