Therapeutic Drug Monitoring of Mycophenolate Mofetil in Lupus Nephritis

Systemic lupus erythematosus (SLE) is an inflammatory, chronic, and multisystem autoimmune disease characterized by periods of activity and remission. Lupus nephritis (LN) is the most frequent renal complication and is associated with high morbidity, manifesting as nephritic or nephrotic syndrome, complement consumption, and positivity for anti-double-stranded DNA antibodies. Mycophenolate mofetil (MMF) is an immunosuppressive agent that modifies the course of LN and is converted into mycophenolic acid (MPA), its measurable active metabolite. However, MMF exhibits complex interindividual and interethnic variability in metabolism, reinforcing the need for personalized strategies through therapeutic drug monitoring (TDM) to ensure renal remission. The objective of this study is to determine whether the implementation of MPA TDM results in a higher rate of renal remission over 12 months compared with standard treatment. This is a randomized, blinded clinical trial to be conducted at a teaching hospital in Maranhão over a 12-month period. From an estimated population of 187 eligible patients with LN receiving MMF, 100 consecutive participants will be randomized (50 per group). MPA monitoring will occur at three time points (T1, T2, T5), while clinical and laboratory outcome assessments will be performed quarterly (T1-T5). The primary outcome will be the renal remission rate; secondary outcomes include serum MPA levels, adverse events, hospitalizations, and medication adherence. This study will generate evidence on precision therapeutics applied to MMF in LN within the Brazilian public health system (SUS), particularly regarding the pilot use of TDM for dose optimization and maximization of clinical response.