ERBB2 and breast cancer: ARX788 is currently being tested in several phase II clinical trials in advanced metastatic HER2+ breast cancer resistant to other anti-HER2 therapies (NCT05018702, NCT048299604); in combination with the small HER2 tyrosine kinase inhibitor pyrotinib (NCT04983121); in HER2-low breast cancer (NCT05018676, phase II); and in other HER2+ tumors (NCT05041972, NCT03255070, and NCT02512237) (Table 1).