Table 3.

Site-specific antibody conjugation with proteins and peptides.

Categories of Payloads	MOA of Payload	Antibody Formats	Specific Site Used	Conjugation Chemistry	References
Proteins	Enzyme	mAb	C-terminal FGly in HC	Oxime or Hydrazino-iso-Pictet–Spangler reaction and click chemistry	[88,89]
	Immunotoxin	mAb	M252 in Fc	Peptide-directed photo-cross-linking	[42]
	Cytosolic delivery through toxin	mAb	HC C-terminal LPSTGGK	Sortase A (SrtA)-mediated transpeptidation	[90]
Antibody fragments	Bispecific Fab as T cell engager (Fab-Fab)	Fab	Unnatural amino acid in LC or HC	Click chemistry	[91,92,93]
	Biparatopic scFv	scFv	C-terminus	SpyTag and SpyCatcher-mediated ligation	[94,95]
Peptides or cyclic peptides	Antimicrobial macrocyclic peptide (ABCs)	mAb	HC C-terminal (GS)6-LPETGGG	Sortase A (SrtA)-mediated transpeptidation	[96]
	Internalization through CPP	Nb	C-terminal LPETG	Sortase A (SrtA)-mediated transpeptidation	[97]
	Cytosolic delivery through cyclic CPP	Nb	C-terminus	Intein-mediated thioester (or expressed protein ligation)	[98]