ERBB2 and breast cancer: A smaller phase Ib trial (NCT03032107) evaluating the combination of T-DM1 and pembrolizumab among 20 pretreated patients with HER2-positive BC has reported an ORR of 20% (95% CI 5.7–43.7%) and median PFS of 9.6 months (95% CI 2.8–16 months).