Tadekinig-α is a human recombinant IL-18BP (rhIL-18BP) with an IL-18 high affinity and has been investigated in two serious inflammatory conditions that are associated with unusual elevation of IL-18 plasma levels; AOSD/sJIA and a refractory HLH bearing a gain of function mutation named NLR family CARD domain containing 4 (NLRC4)-related MAS. This evidence concerns the gene IL18BP and adult-onset Still disease.