Targeted therapies in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic, multisystem disorder characterised by loss of tolerance to endogenous nuclear antigens and autoantibody formation. Recent insight into the immunopathogenesis of lupus has provided the foundation for a novel class of agents which target specific, dysregulated components of the immune system. Efforts have focused predominantly on B-cell depleting therapies, of which belimumab was the first to demonstrate success in phase III studies and thus receive marketing authorisation. Off-label prescribing of rituximab in refractory cases is common and supported by uncontrolled studies, which suggest a favourable risk:benefit profile. However, two placebo-controlled trials failed to show benefit, possibly because of inappropriate patient selection and other aspects of trial methodology. Inhibition of dysregulated co-stimulatory signals and cytokines are other therapeutic strategies currently under investigation. Some candidate drugs failed to meet primary endpoints in early-phase clinical trials, yet demonstrated clinical benefit when alternative assessment criteria were applied or specific patient sub-groups analysed. Well-designed studies of greater size and duration are needed to clarify the therapeutic utility of these agents. Future immunomodulatory strategies targeting interferon-alpha, T cells, oxidative stress and epigenetic abnormalities may reduce multisystem disease activity and prolong survival in this complex and heterogeneic disease.