MUC1 and neoplasm: The Muc1-Bi-1 bispecific antibody was first constructed by fusing two single domain antibodies, anti-Muc1 VHH (GenBank: FJ799116.1) targeting Muc1 positive tumor cells, and anti-CD16 VHH, which binds CD16 on NK cells and recruits NK cells [23] (Fig 1A top sequence).