Study of Ambrisentan With Antifibrotic Agent Combination Therapy in Diffuse Systemic Sclerosis

This is an open label, single center study to determine the efficacy and safety of ambrisentan and antifibrotic agent combination in systemic sclerosis. Up to twenty patients will be recruited within the next year who have early diffuse systemic sclerosis and are presently receiving treatment with any of the following antifibrotic agents - cellcept, colchicine, azathioprine, D-penicillamine, methotrexate or cyclophosphamide. Ambrisentan will be added to the present agent and then followed for 12 months. Patients, male or female, \> 18 years with a clinical diagnosis of systemic sclerosis fulfilling the criteria of the American College of Rheumatology (formerly the American Rheumatism Association) classification criteria for systemic sclerosis (24), and diffuse cutaneous involvement based on the criteria of LeRoy et al A thorough baseline evaluation will determine the extent and severity of systemic sclerosis in the individual patients using laboratory studies and the clinical evaluation. Monthly follow-ups will capture any safety issues related to the combination therapy based again on laboratory studies and clinical evaluation. At the six month and twelve month follow-up a thorough evaluation will again be undertaken to evaluate the extent and severity of the disorder. Event driven follow-ups will also take place to record and establish any safety issues that may arise. Clinical end-points will be the focus of this study. Dosing of ambrisentan will begin at 5mg daily for the first month. Half the patients will remain at 5mg daily, while the remaining patients will be increased to a maintenance dose of 10mg daily on the fourth week. Subjects will continue their present dose and schedule of disease modifying/antifibrotic medication for the duration of the study.