A Study of Subcutaneous Abatacept to Treat Diffuse Cutaneous Systemic Sclerosis

Inclusion Criteria:

   1. Diagnosis of Systematic Sclerosis (SSc), as defined using the 2013 American College of
   Rheumatology/ European Union League Against Rheumatism classification of SSc

   2. Diffuse Systemic Sclerosis (dcSSc) as defined by LeRoy and Medsger

   3. Disease duration of ≤ 36 months (defined as time from the first non-Raynaud phenomenon
   manifestation)

   4. For disease duration of ≤ 18 months: ≥ 10 and ≤ 35 mRSS units at the screening visit

   5. For disease duration of >18-36 months: ≥ 15 and ≤ 45 mRSS units at the screening visit
   and one of the following:

      - Increase ≥ 3 in mRSS units compared with the last visit within previous 1-6
      months

      - Involvement of one new body area with ≥ 2 mRSS units compared with the last visit
      within the previous 1-6 months

      - Involvement of two new body areas with ≥ 1 mRSS units compared with the last
      visit within the previous 1-6 months

      - Presence of 1 or more Tendon Friction Rub

   6. Age ≥ 18 years at the screening visit

   7. If female of childbearing potential, the patient must have a negative pregnancy test
   at screening and baseline visits

   8. Oral corticosteroids (≤ 10 mg/day of prednisone or equivalent) and NSAIDs are
   permitted if the patient is on a stable dose regimen for

      - 2 weeks prior to and including the baseline visit.

   9. ACE inhibitors, calcium-channel blockers, proton-pump inhibitors, and/or oral
   vasodilators are permitted if the patient is on a stable dose for ≥ 2 weeks prior to
   and including the baseline visit.

Exclusion Criteria:

   1. Rheumatic disease other than dcSSc; it is acceptable to include patients with
   fibromyalgia and scleroderma-associated myopathy

   2. Limited cutaneous systemic sclerosis or sine scleroderma at the screening visit

   3. Major surgery (including joint surgery) within 8 weeks prior to screening visit

   4. Infected ulcer prior to randomization

   5. Treatment with any investigational agent within ≤ 4 weeks (or 5 half-lives of the
   investigational drug, whichever is longer) of the baseline visit

   6. Previous treatment with cell-depleting therapies, including investigational agents,
   including but not limited to, CAMPATH, anti-CD4, anti-CD5, anti-CD3, anti-CD19, and
   ABA

   7. Anti-CD20, and cyclophosphamide within 12 months prior to baseline visit.

   8. Use of Intravenous Immunoglobulin (IVIG) within 12 weeks prior to baseline visit

   9. Previous treatment with chlorambucil, bone marrow transplantation, or total lymphoid
   irradiation

10. Immunization with a live/attenuated vaccine within ≤ 4 weeks prior to the baseline
   visit

11. Treatment with methotrexate, hydroxychloroquine, cyclosporine A, azathioprine,
   mycophenolate mofetil rapamycin, colchicine, or D-penicillamine, within≤ 4 weeks prior
   to the baseline visit

12. Treatment with etanercept within ≤ 2 weeks, infliximab, certolizumab, golimumab, ABA
   or adalimumab within ≤ 8 weeks, anakinra within ≤ 1 week prior to the baseline visit

13. Pulmonary disease with FVC ≤ 50% of predicted, or DLCO (uncorrected for hemoglobin ) ≤
   40% of predicted at the screening visit

14. Pulmonary arterial hypertension (PAH) as determined by right heart catheterization or
   on PAH approved medications for PAH. It is acceptable to use PDFE-5 inhibitors for
   Raynaud's and digital ulcers.

15. Subjects at risk for tuberculosis (TB). Specifically excluded from this study will be
   participants with a history of active TB within the last 3 years, even if it was
   treated; a history of active TB greater than 3 years ago, unless there is
   documentation that the prior anti-TB treatment was appropriate in duration and type;
   current clinical, radiographic, or laboratory evidence of active TB; and latent TB
   that was not successfully treated (≥ 4 weeks).

16. Positive for hepatitis B surface antigen prior to the baseline visit

17. Positive for hepatitis C antigen, if the presence of hepatitis C virus was also shown
   with polymerase chain reaction or recombinant immunoblot assay prior to baseline visit

18. Subjects at risk for tuberculosis (TB). Specifically excluded from this study will be
   participants with a history of active TB within the last 3 years, even if it was
   treated; a history of active TB greater than 3 years ago, unless there is
   documentation that the prior anti-TB treatment was appropriate in duration and type;
   current clinical, radiographic, or laboratory evidence of active TB; and latent TB
   that was not successfully treated (≥ 4 weeks).

19. Any of the following at the screening visit: Hemoglobin <8.5 g/dL; WBC < 3,000/mm3 (<3
   x 109/L); platelets < 100,000/mm3 (<3 x 109/L); serum creatinine > 2 x ULN; serum ALT
   or AST > 2 x ULN

20. Severe skin thickening (mRSS 3) on the inner aspects of thighs, upper arms, or abdomen

21. Patients with a history of anaphylaxis to abatacept