A recently published phase Ib study enrolling highly pretreated patients with advanced HER2-expressing/mutated solid tumors, including HER2-low breast cancer, revealed a remarkable overall response rate (ORR) of 37.0% (95% CI: 24.3–51.3%) in HER2-low breast cancer and an impressive median duration of response of 10.4 months (95% CI: 8.8 month—not evaluable), with no apparent differences in ORR between 1+ and 2+ IHC tumors (35.7% vs. 38.5%)9. The gene discussed is ERBB2; the disease is breast cancer.