Table 1.

Characteristics of the antibody–drug conjugates currently approved or in late stages of development (phase III studies)

Agent	Target	Payload (mechanism of action)	DAR	Bystander effect	US FDA-approved indications	Toxicities of special interest
Ado-trastuzumab emtansine	HER2	Maytansine (antimicrotubule)	3–4	No	HER2+ MBC previously treated with trastuzumab and taxane Early-stage HER2+ BC with residual disease following neoadjuvant therapy (adjuvant)	AST/ALT elevations, thrombocytopenia, neuropathy
Trastuzumab deruxtecan	HER2	Exatecan (topoisomerase 1 inhibitor)	8	Yes	HER2-positive MBC previously treated with trastuzumab, taxane and T-DM1	ILD, neutropenia, anemia, nausea
Trastuzumab duocarmazine (SYD985)	HER2	Duocarmycin prodrug	2.8	Yes	Not approved to date	Fatigue, conjunctivitis, dry eyes
Disitamab vedotin (RC48-ADC)	HER2	Monomethyl auristatin E	4	No	Not approved to date	Neutropenia, AST/ALT elevations
Sacituzumab govitecan	TROP-2	SN-38 (topoisomerase 1 inhibitor)	7.6	Yes	Metastatic TNBC previously treated with at least two lines of CT in the metastatic setting	Neutropenia, anemia, diarrhea
Ladiratuzumab vedotin	LIV-1	Monomethyl auristatin E	4	No	Not approved to date	Neutropenia, anemia

ALT alanine transaminase, AST aspartate aminotransferase, BC breast cancer, CT chemotherapy, DAR drug-to-antibody ratio, HER2+ HER2-positive by American Society of Clinical Oncology/College of American Pathologists guidelines, ILD interstitial lung disease, MBC metastatic breast cancer, T-DM1 trastuzumab emtansine, TNBC triple-negative breast cancer