Blinatumomab is a bispecific molecule of very small size made from a single polypeptide chain comprising the variable heavy chain and light chain of an anti-CD3 monoclonal antibody joined to the variable heavy chain and light chain of an anti-CD19 monoclonal antibody. The idea is that the antibody redirects the T-cell lysis to the tumor B-cell.
The BiTE antibody transiently creates a cytolytic synapse between a cytotoxic T-cell and the cancer target cell; in this case a B-cell lymphoma cell. Granules containing granzymes and the pore-forming protein, perforin, fuse with the T-cell membrane and discharge their toxic content leading to the death of the target cell
Blinatumomab has a very short serum half-life of only 2-3 hours and therefore must be administered by continuous infusion over 4-8 weeks using portable minipumps.