Bispecific antibodies

A classic monoclonal antibody has one target; a bispecific antibody has two. In the design most used in cancer treatment — sometimes called a bispecific T-cell engager (BiTE) — one arm attaches to a marker on the cancer cell (for example CD19 on leukaemia cells or BCMA on myeloma cells) and the other arm attaches to CD3, a protein present on T cells. By holding the T cell right next to the cancer cell, the antibody activates it exactly where it is needed and helps it kill the tumour cell, even when the T cell would not have recognized the cancer on its own. Because the drug is a ready-made protein rather than a cell product, it does not require collecting and engineering the patient's own cells, but it must be given repeatedly. Activating many T cells at once can release large amounts of cytokines, so — as with CAR-T — cytokine release syndrome with fever and low blood pressure is a known risk, alongside infusion reactions and flu-like symptoms; the first doses are therefore given under close medical supervision. According to NCI, teclistamab is one of three bispecific T-cell engagers approved by the FDA for adults with multiple myeloma that has come back or stopped responding after several earlier therapies.