A Study of Patients Having Pulmonary Hypertension Associated With Sickle Cell Disease and Completing an ASSET Study

This study will assess the safety and efficacy of bosentan therapy (in a study known as ASSET) for patients who have high blood pressure in the lungs associated with sickle cell disease. That form of hypertension places people at risk for complications, including shortness of breath, pain, pneumonia, and death. Previous studies have shown that bosentan can be helpful in reducing pulmonary hypertension. Patients ages 16 and older who have completed the 16-week treatment in the ASSET 1 or ASSET 2 study and who are not pregnant or breastfeeding may be eligible for this study. The research will be conducted in about 25 hospitals in the United States and Europe. Up to 30 participants will be enrolled. The screening visit will involve a physical examination, blood sample of about 3 teaspoons for laboratory tests, and a pregnancy test. Patients' doctors will give them bosentan tablets (62.5 mg each), to take one in the morning and one in the evening. After 1 month, patients will be told whether the dose should be increased to 125 mg tablets to take twice a day. Two weeks after the increase in dose, a blood test will be done to analyze the drug's effects on the liver. After the start of treatment, patients will return for visits every 6 months, when there will be a 6-minute walking test to measure exercise capacity and evaluate shortness of breath. There will be follow-up for patients up to the end of the study and for 28 days after the last dose of bosentan is taken, to collect information about side effects. Some patients on bosentan have had changes in liver function and red blood cell count. Side effects commonly reported are headache, flushed appearance, inflammation of the throat and nasal passages, and gastrointestinal symptoms. If patients have sudden worsening in breathing in the first few weeks after taking bosentan, they should immediately tell their doctors, because it may be necessary to change the treatment.

The object of this study is to assess long-term safety, tolerability and efficacy of bosentan in patients with pulmonary hypertension (PH) associated with sickle cell disease (SCD). The study population will include male and female patients with sickle cell disease (SS,S-beta-Thalassemia) who have previously completed the 16-week treatment period of the double-blind study of bosentan (ASSET 1 or ASSET 2). Patients who meet all the inclusion criteria and none of the exclusion criteria will be started on 62.5 mg bid for 4 weeks and then start the maintenance dose of 125 mg bid (or stay on 62.5 mg if their weight is less than 40kg/90lbs). Patients will be divided into two groups. Group A will consist of patients who begin this study within 4 weeks of completing ASSET 1 or ASSET2. Group B will consist of patients who begin this study longer than 4 weeks after completing ASSET I or ASSET 2. Patients will remain on drug until the FDA approves the drug for use in patients with pulmonary hypertension or until the sponsor decides to stop the study.