A Randomized, Double-Blind, Placebo-Controlled, Phase II Multicenter Trial of a Monoclonal Antibody to CD20 (Rituximab) for the Treatment of Systemic Sclerosis-Associated Pulmonary Arterial Hypertension (SSc-PAH)

Inclusion Criteria

– Subject must be between the ages of 18 and 75 at the time of randomization.

– Clinical diagnosis of systemic sclerosis (either limited or diffuse cutaneous disease).

– Diagnosis of SSc-PAH within the past 5 years

– Screening 6MWD of at least 100 meters.

– Subjects must have been treated with background medical therapy for PAH  for a minimum of 12 weeks and have been on stable dose(s) of those medical therapy(ies) for at least 4 weeks prior to randomization.

Exclusion Criteria

– Persistent hypotension with systolic blood pressure (SBP) < 90 mmHg.

-Treatment with cyclophosphamide within 4 weeks of randomization.

– Treatment with biologic agents (including, but not limited to TNF inhibitors, anakinra, abatacept, and tocilizumab) within 4 weeks prior to treatment

– If being treated with methotrexate, azathioprine, mycophenolate, cyclosporine, hydroxychloroquine, penicillamine, and/or prednisone at ≤ 10mg daily, changes in dosage within 4 weeks prior to randomization. Subjects taking prednisone or equivalent corticosteroid > 10mg daily are excluded.

– History of coronary artery disease

– Interstitial lung disease as characterized by diffuse pulmonary infiltrates on chest xray and a total lung capacity (TLC) of < 70% predicted.