Interferon-targeted therapy in systemic lupus erythematosus: Is this an alternative to targeting B and T cells?

Clinical trials of investigational agents in systemic lupus erythematosus (SLE) have focused on targeting dysregulated B and T cells; however, recent translational research findings of the importance of the dysregulation of the innate immune system in SLE have led to clinical trials that target interferon. Three biologics that target type I interferons have been tested for their efficacy and safety in active SLE patients; these phase II trials have tested the hypothesis that down-regulation of interferon-regulated gene expression (the interferon signature) lessen the clinical burden of SLE. Rontalizumab, an anti-interferon-α monoclonal antibody, was studied in patients who had discontinued immunosuppressants. This study failed to show efficacy as assessed by both two outcome assessments; however, in low interferon signature patients, response was higher and corticosteroid usage was less in rontalizumab-treated patients. Sifalimumab, another anti-interferon-α monoclonal antibody, was studied in patients who remained on standard of care therapy. This study showed significantly better efficacy in patients treated with two sifalimumab dosages; significant differences were seen in the high interferon signature group. In a similar design and in a similar population as the sifalimumab study, anifrolumab, a monoclonal antibody that binds to a type I interferon receptor, was studied in patients who remained on standard of care therapy. In this study, one dosage group demonstrated efficacy and statistically significant effects were achieved in both tested dosage groups with secondary end points. Oral corticosteroid reduction to ≤7.5 mg daily was achieved in one of the tested dosage groups and organ-specific outcomes were significantly improved in that same group. For all studies, no significant differences in serious adverse effects were seen; although, herpes zoster infections were increased in sifalimumab- and anifrolumab-treated patients and influenza rates were increased in anifrolumab-treated patients. Anifrolumab is currently in pivotal phase III studies. Data appear to support the concept that targeting type I interferon in SLE patients associates with clinical efficacy and safety. Further data are forthcoming from ongoing phase III clinical trials of anifrolumab. Other drug development efforts should be considered that target plasmacytoid dendritic cells and toll like receptors given the effects these components have on interferon production.