The successful phase IIb trial of anifrolumab in patients with moderate or severe SLE (93) put the grounds for the conception of patient stratification based on endotypic features, e.g., the magnitude of the IFN signature, and in contrast to the failure of the first phase III trial of anifrolumab in SLE (TULIP1) (94), the drug was successful in the subsequent phase III trial TULIP2 (95). This evidence concerns the gene IFNA1 and systemic lupus erythematosus.