A Study of the Efficacy and Safety of Belimumab in Adults With Systemic Sclerosis Associated Interstitial Lung Disease

Inclusion Criteria:

1. Participant is 18 years of age inclusive, or older at the time of signing theinformed consent.

2. Documented diagnosis of SSc as defined by the American College of Rheumatology /European League Against Rheumatism 2013 SSc classification criteria.

3. Diffuse cutaneous disease, defined as presence of thickened skin with mRSS >0 overat least one skin area proximal to elbows and/or knees in addition to distal areasinvolvement on Day 1.

4. Total mRSS ≥15 on Day 1.

5. Evidence of interstitial lung disease on centrally read screening HRCT.

6. Anticentromere antibody negative on central test at screening.

7. Evidence for active or progressive disease

8. Participant has an area of uninvolved or mildly thickened skin that, in the opinionof the investigator, would allow SC injection at the abdomen or the front, middleregion of the thigh.

9. Participant is capable and willing to self-administer the study medication or has acaregiver who is capable and willing to administer the study medication throughoutthe study.

10. A female participant is eligible to participate if she is not pregnant orbreastfeeding, and one of the following conditions applies: Is a Woman of Non-Childbearing Potential (WONCBP) OR Is a Woman of ChildbearingPotential (WOCBP) and using a contraceptive method that is highly effective.

11. Capable of giving signed informed consent.

Exclusion Criteria:

1. Systemic sclerosis-like illness, including but not limited to localized scleroderma (morphoea), eosinophilic fasciitis, sclerodermoid graft-versus-host disease, fibromucinous conditions (scleroedema, scleromyxoedema), scleroderma-like conditions thatare associated with environmental chemical and drug exposure (e.g., toxic rapeseedoil, vinyl chloride, bleomycin, gadolinium-based contrast agents [nephrogenicsystemic fibrosis], or due to metabolic disease).

2. Primary diagnosis of a rheumatic autoimmune disease other than dcSSc, including butnot limited to rheumatoid arthritis, systemic lupus erythematosus, polymyositis,dermatomyositis, systemic vasculitis, Sjogren's syndrome, antisynthetase syndrome,or mixed connective tissue disease, as determined by the investigator.

3. FVC ≤45% of predicted, or a DLco (corrected for hemoglobin) ≤40% of predicted orrequiring supplemental oxygen at screening.

4. Pulmonary arterial hypertension, as determined by the investigator at, or prior tofirst day of dosing (Day 1).

5. SSc renal crisis within 6 months prior to the first day of dosing (Day 1).

6. History or presence of cardiovascular, respiratory, hepatic, renal,gastrointestinal, endocrine, hematologic, or neurological disorders capable ofsignificantly altering the absorption, metabolism, or elimination of drugs;constituting a risk when taking the study intervention or interfering with theinterpretation of data.

7. Obstructive pulmonary disease (pre-bronchodilator FEV1/FVC <0.7).

8. Significant emphysema on screening HRCT (extent of emphysema exceeds extent of ILD).

9. Previous or planned major organ transplant (e.g., heart, lung, kidney, liver) orbone marrow transplant (e.g., autologous stem cell transplant).

10. Treatment with biologic agents, such as intravenous immunoglobulin or monoclonalantibodies, including marketed drugs, within 3 months or 5 half-lives (whichever islonger) prior to dosing.

11. Treatment with rituximab within 6 months prior to Day 1.

12. Treatment with non-biologic systemic immunosuppressive medication, other thanmycophenolate, methotrexate or azathioprine (including, but not limited tocyclosporine A, tacrolimus, leflunomide, oral or parenteral gold, Janus kinase (JAK)inhibitors) within 3 months prior to Day 1.

13. Treatment with cyclophosphamide (oral or intravenous) within 6 months prior to Day

15. Use of anti-fibrotic agents including colchicine, D-penicillamine, pirfenidone ortyrosine kinase inhibitors (e.g., nintedanib, nilotinib, imatinib, dasatinib) within 4 weeks prior to Day 1.

16. Cytotoxic drugs such as, chlorambucil, nitrogen mustard, or other alkylating agentswithin 6 months of Day 1.

17. Treatment with IM or IV corticosteroids within 1 month prior to Day 1.