Bi-specific killer engagers (BiKEs) carry two single chain variable fragments (scFv) that bind to an activating NK receptor such as CD16 and a tumor-specific antigen such as CD19 or CD33, while tri-specific killer engagers (TRiKEs) are BiKEs that contain an additional scFv to further enhance NK cell cytotoxicity [176]. The gene discussed is CD33; the disease is neoplasm.