Treatment of Systemic Lupus Erythematosus (SLE) With N-acetylcysteine

Subjects will take NAC in a dose range of 2.4 g/day to 4.8 g/day which will be titrated to tolerance during an initial 3-month open label period. After the 3-month open label period, patients in each arm will continue taking equal numbers of capsules representing a dosage that has been titrated to tolerance. As an example, the patients tolerating 2.4 g/day, or 4 capsules containing 600 mg of NAC, after 3 months will be randomized to take 4 NAC or 4 placebo (2.4 g/day dextrose) capsules twice daily for the 9 subsequent months. The primary outcome variable will be the response (yes/no) in the SLE Respinder Index or SRI at Month 12 (reduction ≥ 4 points in SELENA-SLEDAI score and therefore also called SRI-4; no new BILAG A organ domain score and no more than 1 new BILAG B organ domain score; and no worsening in Physician's Global Assessment (PGA) score) by ≥ 0.3 points versus baseline). A positive response will also require no treatment failure, defined as the need for non-protocol treatment, i.e., new or increased immunosuppressives or antimalarials; increased or parenteral corticosteroids; or premature discontinuation from study treatment. Corticosteroids can be tapered off at the investigator's discretion, based on disease activity. Four weeks after randomization, once tapered, corticosteroids can only be increased again to the dosage preceding the last taper step; any larger increase will be deemed a treatment failure. In addition, any increase in corticosteroid dosage during the last 3 months of the trial will result in declaration of treatment failure. We will monitor tolerance and safety, and assess SLEDAI, BILAG, FAS, PROMIS, ASRS, prednisone use, liver and bone marrow function as secondary outcomes.