Trastuzumab, tested only as a single agent, has been shown to achieve 7% response in heavily pretreated patients with AOC with 3+ and 2+ HER2 immunostaining by immunohistochemistry (IHC).

The antibody-drug conjugate trastuzumab deruxtecan has been approved since January 2021 for pretreated adults with HER2-positive breast cancer that has metastasized or can no longer be operated on.