bispecific antibody

A bispecific antibody is an engineered antibody with two different grips, so a single molecule can grab two distinct targets at once. A normal antibody is like a tool with two identical jaws; a bispecific is rebuilt so each jaw clamps a different thing, letting it physically link two players together.

This dual grip enables tricks a single-target antibody cannot perform. The most famous example pulls an immune cell and a cancer cell into direct contact: one arm binds a marker on a T cell, the other binds a marker on the tumor, forcing the T cell to attack a cancer cell it would otherwise ignore. Other bispecifics block two signals at once or shuttle a payload across a barrier.

Building such molecules is challenging because the two halves of an antibody must be made to pair correctly rather than scrambling, and engineering solutions like the 'knobs-into-holes' design exist to fix this. Like other antibody drugs, bispecifics are large proteins given by infusion, and bridging two cell types can bring potent but sometimes dangerous immune effects.