Anti-Human CD3 x CD19 (Blinatumomab) [Clone AMG103],Leinco,C2530

Blinatumomab is a Bispecific T cell Engager (BiTE) antibody developed as a cancer immunotherapeutic drug 1,2,3,4 . Blinatumomab induces apoptosis of target B cells by binding simultaneously to the C19 surface antigen of all B cells (healthy and malignant) as well as the epsilon subunit of the CD3 invariant antigen of the T cell TCR (T cell receptor) 4 . Binding is achieved via two large single-chain variable fragments arranged in tandem, with the CD19-binding fragment at the N-terminal and the CD3 binding fragment at the C-terminal. The fragments are linked by a flexible, non-immunogenic, non-glycosylated five amino acid peptide (four glycine and one serine), which confers a high degree of rotational flexibility to facilitate simultaneous epitope binding. In this way, blinatumomab targets malignant B cells for apoptosis via CD19, a B-lymphocyte-specific receptor responsible for promoting activation and differentiation of normal B cells that functions as a costimulatory molecule of the B cell receptor 2 . Blinatumomab binding forces the colocalization of cytotoxic T lymphocytes and B cells expressing CD19 4 . A structurally normal cytolytic immune synapse is formed, and, in T cells, activation events trigger the delivery of granzyme and perforin into the synaptic space, inducing apoptosis of the targeted B cells. Recruitment and activation of T cells occurs after the second arm of blinatumomab binds to the target cell antigen. An activated T cell can kill several B cells. Blinatumomab is a B lineage-specific antitumor mouse monoclonal antibody 4 . The CD19-targeting fragment is derived from the parental murine monoclonal antibody HD37, while the CD3-binding fragment is derived from the parental murine monoclonal antibody L2K-07 1,3,4 . Blinatumomab is only one-third the size of traditional antibodies at 504 amino acids and a molecular weight of 55 kDa 4 . Other names for blinatumomab are MT103, MEDI‐538, bscCD19xCD3, and AMG103. Blinatumomab is a non-glycosylated fusion protein.