Among 16 tumor specimens with sufficient tissue quality for NGS, CCNE1 amplification was the most common co-occurring copy number alteration, found in 40% of HER2-positive tumors and trended to lack of response to HER2-targeted therapy (66.7% of non-responders had CCNE1 amplification versus 22.2% of responders, P = 0.08). Here, ERBB2 is linked to neoplasm.