Mild PAH improved by early treatment with bosentan

Implications: While functional class II (FC II) PAH patients have been included in previous clinical trials, the EARLY trial is the first study to concentrate (ie recruit exclusively) FC II PAH patients.  This is important because the definition of functional class II is that a patient has a sight limitation in physical activity. Understanding "slight" is not so easy in clinical practice and there has been some reservation in treating "slightly" ill patients with very expensive drugs without better outcome studies in this target group. Thus the results of the EARLY study (Lancet June 2008) are welcome news to the PAH community.  Analyses were done with 168 patients and showed significant improvements in pulmonary vascular resistance and a strong trend (p = 0.075) toward improvement in 6 minute walk distance in bosentan-treated patients.  These results will certainly compell clinicians to treat patients with "slight" PAH more aggressively.

Analysis:  These results should lead to more widespread use of bosentan (and probably other PAH medications) for FC II patients and help Actelion's bottom line.  Th FCII group of patients may be considerably larger than previously thought and, thus, other companies in the PAH "space" may be benefited as well.