TNFSF13B and systemic lupus erythematosus: Billions of dollars have been spent on research and development and clinical trials over the past few decades, yet belimumab (monoclonal antibody against B-cell-activating factor of the tumour-necrosis-factor family, BAFF) is the only US Food and Drug Administration–approved targeted biological therapy for SLE (Navarra et al., 2011; Furie et al., 2011), and there is a great need to develop new effective therapies (Merrill et al., 2018).