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Sitaxsentan for the Treatment of Pulmonary Arterial Hypertension

A 1-Year, Prospective, Open-Label Observation of Outcome and Survival

      Background

      Despite advances in the management of pulmonary arterial hypertension (PAH), the mortality rate remains excessive. Long-term efficacy evaluations are needed to guide therapeutic management. The purpose of this study is to present 1-year observational data with two endothelin antagonists, sitaxsentan and bosentan, in a prospective, open-label study.

      Methods

      The present study was a prospective, international, multicenter, randomized, open-label extension of the Sitaxsentan To Relieve Impaired Exercise-2 trial. All-cause mortality, time to discontinuation (all causes) from monotherapy, time to discontinuation due to adverse events, time to elevations in and time to discontinuation due to elevated hepatic transaminases, and time to first clinical worsening event were evaluated. Patients initially receiving sitaxsentan at 50 mg were excluded from the main analysis. The distributions of time-to-event variables are estimated using Kaplan-Meier methods, and treatment effects are evaluated using the Cox proportional hazards model.

      Results

      Patients treated with sitaxsentan at 100 mg had 96% overall survival and a 34% risk for a clinical worsening event by 1 year. In addition, there was a 6% risk of elevated aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) levels > 3 × upper limit of normal range (ULN) at 1 year and a 15% risk of discontinuation due to adverse events. Patients treated with bosentan had 88% overall survival and a 40% risk of a clinical worsening event by 1 year. In addition, there was a 14% risk for elevated AST and/or ALT levels > 3 × ULN at 1 year and a 30% risk of discontinuation due to adverse events.

      Conclusions

      At 1 year, sitaxsentan therapy appears safe and efficacious for patients with PAH; reductions in mortality and the risk for clinical worsening events provide support for durability of efficacy.

      Key words

      Abbreviations:

      ALT (alanine aminotransferase), AST (aspartate aminotransferase), CI (confidence interval), ET (endothelin), ETRA (endothelin-receptor antagonist), IPAH (idiopathic pulmonary arterial hypertension), PAH (pulmonary arterial hypertension), PAH-CHD (pulmonary arterial hypertension associated with congenital heart defect), PAH-CTD (pulmonary arterial hypertension associated with connective tissue disease), 6MWD (6-min walk distance), STRIDE (Sitaxsentan To Relieve Impaired Exercise), ULN (upper limit of normal range), WHO (World Health Organization)
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      Linked Article

      • Correction: Chest 2008; 134:775–782
        CHESTVol. 135Issue 4
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          In the October 2008 issue, in the article by Benza et al, “Sitaxsentan for the Treatment of Pulmonary Arterial Hypertension: A 1-Year, Prospective, Open-Label Observation of Outcome and Survival” (Chest 2008; 134:775–782), CHEST inadvertently omitted the conflicts of interest statements for the authors. CHEST regrets the omission. They are as follows: Dr. Barst has received grants, been a consultant for and/or has participated in speaking activities for Actelion, Encysive, Gilead, Pfizer, Novartis, United Therapeutics, GlazoSmithKline, and INO.
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