Development of atacicept, a soluble fusion protein decoy receptor (incorporating the ligand-binding domain of the transmembrane activator and cyclophilin ligand activator (TACI, also known as TNFRSF13B)), designed to block two B-cell cytokines B-cell activating factor of the TNF family (BAFF, also known as BLyS, TNFSF13B) and a proliferation-induced ligand (APRIL, TNFSF13), unexpectedly led to severe adverse events and exacerbated symptoms and lesions when tested in clinical trials in MS patients15. This evidence concerns the gene TNFSF13B and myeloid sarcoma.