Construction of bispecific antibodies by specific pairing between the heavy chain and the light chain using removable SpyCatcher/SnoopCatcher units.

During the production of bispecific antibodies (bsAbs), nonspecific pairing results in low yields of target bsAb molecules, an issue known as the "mispairing problem." Several antibody engineering techniques have been developed to overcome mispairing issues. Here, we introduce "bsAb by external pairing and excision" (BAPE), a novel chain pairing method that induces specific chain pairing by fusing external SpyCatcher/Tag and SnoopCatcher/Tag units.