VIENNA — Patients with functional class II pulmonary arterial hypertension had significantly slower disease progression when treated with bosentan in a study with 185 patients, a finding that may shift the time to diagnose and start treatment of this disease.

The results support starting treatment of pulmonary arterial hypertension “as soon as possible after the diagnosis,” Dr. Nazzareno Galiè said at the annual congress of the European Society of Cardiology. “In PAH it's very important to prevent deterioration, and that's what treatment with bosentan does. The results show that PAH is a progressive disease, even in class II, highlighting the need for early diagnosis and treatment.”

The Endothelin Antagonist Trial in Mildly Symptomatic PAH Patients (EARLY) study “is the only study to focus on class II patients,” and it included a strict definition of class II, said Dr. Galiè, professor of cardiology and head of the Pulmonary Hypertension Centre at the University of Bologna, Italy.

Based on these and other findings, applications have been filed with the Food and Drug Administration and similar agencies in other countries to expand bosentan treatment to patients with class II PAH. Bosentan (Tracleer) is already marketed for treating classes III and IV PAH by Actelion. The new study was sponsored by Actelion, and Dr. Galiè is a speaker for and consultant to Actelion.

“The EARLY study results, and the results from [five] other studies that included class II PAH patients, support the benefit of treating patients with less-severe PAH. The added strength of the data from EARLY is that they demonstrated in a pure cohort of class II patients that early treatment may delay progression of the disease,” commented Dr. Lewis J. Rubin, a coauthor of the study and professor of medicine and director of pulmonary and critical care medicine at the University of California, San Diego. Dr. Rubin is a consultant to Actelion.

The study enrolled patients aged 12 years and older, mean age 44, with PAH rated as functional class II by World Health Organization criteria. The disease could have been idiopathic (as it was in about 60% of patients), or caused by congenital heart disease (17%), connective tissue disease (18%), or HIV infection (5%). The average duration of PAH was about 3 years. Patients were randomized to treatment with either 62.5 mg bosentan b.i.d. for 4 weeks, followed by 125 mg b.i.d. for 5 months, or placebo.

After 6 months of therapy, pulmonary vascular resistance (one of two primary end points) rose from baseline by about 7% among 88 evaluable patients in the placebo group, and fell by about 16% in 80 patients in the bosentan group. The overall effect of bosentan therapy was to lower pulmonary vascular resistance by 23%, compared with placebo, a statistically significant effect.

The second primary end point was change in exercise capacity, measured by distance walked in 6 minutes. By this measure, bosentan was linked to a significant, 19-m boost in distance walked, compared with placebo, Dr. Galiè reported.

Bosentan treatment also led to significant improvements in time to clinical worsening, and a reduction in the percentage of patients whose condition worsened. Symptomatic progression of PAH occurred in 10% of patients on placebo, compared with 1% of the patients treated with bosentan. “With bosentan, there is more preservation of functional class,” Dr. Galiè said. Bosentan also led to significant improvements in self-rated quality of life, and a significant reduction in serum levels of NT-probrain natriuretic peptide (NT-proBNP). The drug was well tolerated, with an adverse event profile similar to the placebo group.

To boost the number of patients with PAH who start treatment early, Dr. Galiè suggested screening for PAH in groups that are known to have a relatively high prevalence of PAH. This includes patients with connective tissue diseases, such as scleroderma, patients infected with HIV, and patients with congenital heart disease.

Three other reports at the meeting dealt with using bosentan to treat PAH; all three studies also were sponsored by Actelion.

One study showed that treatment with bosentan was safe and led to improvements in pulmonary vascular resistance and other measures, Dr. Irene Lang, professor of vascular biology at the Medical University of Vienna, reported at the meeting. Treatment also significantly boosted cardiac index, and cut NT-proBNP levels and dyspnea scores. Another study showed that a single dose of sildenafil in patients on chronic bosentan treatment was safe. The third study showed that the children's formulation had a good safety profile.

“New drugs such as bosentan have dramatically improved outcomes for patients with pulmonary arterial hypertension,” said Dr. Daniel Jones, professor of medicine and dean of the medical school at the University of Mississippi, Jackson, and president of the American Heart Association.

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The study results support the benefit of treating patients withless-severe PAH. DR. RUBIN

Bosentan Slows Progression in Class II PAH