A Study of Subcutaneous Abatacept to Treat Diffuse Cutaneous Systemic Sclerosis

This study is a randomized placebo-controlled double-blind phase 2 trial of patients with dcSSc. Eligible participants will be randomized in a 1:1 ratio to either 125 mg SC abatacept or matching placebo, stratified by duration of dcSSc disease duration (\<18 months vs \>18 to \</=36 months). Study participants will be treated for 12 months on double-blind study medication, followed by an additional 24 weeks of open-label SC abatacept therapy. 86 patients will be randomized in approximately 35 centers in the US, Canada and Europe, with the goal of analyzing 74 participants. The investigators study will test whether abatacept is statistically superior to placebo in reducing the MRSS at month 12 and explore the ability of abatacept to prevent or reverse progression in patients with early disease duration and lower MRSS scores, and reverse established disease in patients with longer disease duration and higher MRSS scores.