The purpose of this study is to evaluate the efficacy and safety of ILT-101 (human recombinant interleukin 2 (IL-2)) in patients with moderate to severe systemic lupus erythematosus.

Interleukin 2 (IL-2) plays an important role on immune homeostasis by acting on T lymphocytes. In systemic lupus erythematosus, there is a so called "insufficiency" in a subpopulation of T lymphocytes, the regulatory T cells (Tregs) leading to altered immune balance between regulatory and effector T cells. These cells seem to play a major role in the physiopathology of the disease. Many researches enlighten the fact that this Tregs/Teffs balance can be restored by administering low dose of IL-2. It is thus assumed that treatment with low dose of IL-2 may impact positively the progression of the disease and thus help patients improving their clinical outcomes.

Inclusion Criteria:

• Confirmed diagnosis of SLE
• Active SLE
• On stable background therapy for 1 month
• Using highly effective contraception

Exclusion Criteria:

• Serious organ failure (renal functional impairment, severe central nervous system manifestations, severe heart failure, liver failure)
• Any clinical evidence of active chronic infection HIV, hepatitis B, hepatitis C
• Clinical significant pleuritis or pericarditis
• Type1 Diabetes and/or CROHN's disease
• Use of Benlysta (belimumab) in the past 4 weeks
• Use of Rituximab in the past 6 months
• Vaccination with live attenuated virus in the last month