Table 1.

Completed phase III clinical trials involving antibody drug conjugates.

	Trastuzumab Emantasine (T-DM1)	Trastuzumab Deruxtecan (T-DXd)	Sacituzumab Govitecan (SG)
Target antigen	HER2	HER2	Trop-2
Linker cleavage	No	Enzymatic	pH-dependent and enzymatic
Membrane-permeable Payload?	No	Yes	Yes
hydrophobic		low
Payload/mechanism of action	Maytansine/ Tubulin inhibitor	Deruxtecan/ Topoisomerase 1 inhibitor	SN-38/ Topoisomerase 1 inhibitor
Drug–antibody ratio (DAR)	3.5:1	8:1	7.6:1
Phase III Setting	HER2-positive ABC 2L [4] Post-neoadjuvant residual disease [5] HER2-positive ABC 3L [14]	HER2- positive ABC 2L [13] HER2-low ABC 2L [21]	TNBC ABC 2L [18] ER/PR+ ABC ≥ 2L [20]
Common AE	fatigue, nausea, musculoskeletal pain, thrombocytopenia, headache, elevated transaminases, reduction in LVEF	nausea, leukopenia, anemia, thrombocytopenia, elevated transaminases, diarrhea, hypokalemia, cough	neutropenia, nausea, diarrhea, fatigue, alopecia, anemia, vomiting, constipation, decreased appetite, rash, abdominal pain

Abbreviations: Advanced breast cancer—ABC; Triple-negative breast cancer—TNBC; prior lines of therapy—L; left ventricular ejection fraction—LVEF.