(Reuters) – Acceleron Pharma Inc <XLRN.O> said on Monday its investigational treatment for a rare, deadly lung disease called pulmonary arterial hypertension met the main goal in a mid-stage trial, sending its shares surging 79%.

The treatment, sotatercept, showed significant reduction in pulmonary vascular resistance versus placebo at week 24.

It also showed significant improvements in patients functional capacity, which was determined by a six minute walk test.

Pulmonary arterial hypertension, or PAH, occurs when arteries in the lungs constrict, forcing the heart to work harder, often leading to heart failure. Its symptoms include shortness of breath and fatigue.

The disease has no cure, but there are treatments on the market that can manage the condition.

The company has a rare blood disorder drug, Reblozyl, in the market.

(Reporting by Dania Nadeem in Bengaluru; Editing by Shinjini Ganguli)