Table 4.

Development of HER3-directed antibody–drug conjugates.

Antibody–Drug Conjugates	Study Population	Clinical Trial Phase	Adverse Events	Status Finding	Reference
U3-1402	Advanced or metastatic CRC	NCT04479436 phase II		Terminated
	Naïve patients with HR + /HER2-early BC	NCT04610528 phase I		Active, not recruiting
	Metastatic or unresectable NSCLC	NCT03260491 phase I	Nausea, vomiting, fatigue, decreased appetite, and alopecia	Active, not recruiting U3-1402 has antitumor activity and a manageable safety profile	[186,187,188]
	HER3 + metastatic BC	NCT02980341 phase I + II	Nausea, vomiting, and decreased appetite	Active, not recruiting In a preliminary analysis, U3-1402 demonstrated antitumor activity and a manageable safety profile	[189,190]
	Metastatic or locally advanced EGFR-mutated NSCLC	NCT04619004 phase II		Active, not recruiting
	Locally advanced or metastatic EGFR-mutated NSCLC	NCT04676477 phase I		Recruiting
	Metastatic BC	NCT04699630 phase II		Recruiting
	Advanced BC	NCT04965766 phase II		Recruiting
	Metastatic or locally advanced EGFR-mutated NSCLC after failure of EGFR TKI therapy	NCT05338970 phase III		Recruiting

NSCLC: non-small cell lung cancer, BC: breast cancer, HNSCC: head and neck squamous cell carcinoma; AEs: adverse events; PFS: progression-free survival; ESCC: esophageal squamous cell carcinoma; CRC: colorectal cancer; OS: overall survival; TKI: tyrosine kinase inhibitor.