Shares of United Therapeutics Corp. shot up 38 percent on news that a preliminary analysis of data from the TRIUMPH-1 Phase III trial of Viveta in pulmonary arterial hypertension (PAH) showed it "robustly met its primary endpoint."

United, of Silver Springs, Md., and it's subsidiary Lung Rx Inc., said they will focus on completing regulatory filings to take the product, an inhaled formulation of treprostinil, to the market.

In the randomized, double-blind, placebo-controlled trial, 235 patients received an approved oral therapy for PAH, either bosentan (Tracleer), an endothelin receptor antagonist, or sildenafil (Revatio), a phosphodiesterase-5 inhibitor. In addition, patients were administered Viveta or placebo in four daily inhalation sessions with a maximum dose of 45 mcg per session over the course of the 12-week trial.

The primary efficacy endpoint was the change in six-minute walk (6MW) distance at 12 weeks measured at peak exposure, defined by the trial protocol as 10-60 minutes after inhalation of Viveta, relative to baseline. A preliminary analysis of results showed an improvement in median 6MW distance by approximately 20 meters (p<0.0006) in patients receiving Viveta compared to patients receiving placebo.

The trough exposure, defined as a minimum of four hours after inhalation of Viveta, for treatment change in 6MW distance at week 12 relative to baseline showed an increase in median 6MW distance of approximately 14 meters (p<0.01). Additionally, the 6MW distance at week six relative to baseline was significantly improved, with an increase in median 6MW distance of approximately 18 meters (p<0.0005).

Preliminary analysis of other secondary efficacy measures, including change in Borg Dyspnea Scale rating (shortness of breath test), NYHA functional class, time to clinical worsening (as defined by death, transplant, atrial septostomy, hospitalization due to PAH or initiation of another approved PAH therapy), and the 6MW distance at treatment day one, did not differ significantly between the Viveta and placebo groups (p>0.05). Analysis of two remaining secondary endpoints, quality of life and signs and symptoms of disease (composite measure), is ongoing.

Full data will be presented at a future medical meeting and in journal articles.

Shares of United (NASDAQ:UTHR) climbed $25.67, to close at $94.11.