Although the addition of trastuzumab did not confer survival benefit in patients with HER2-amplified/overexpressing NSCLC, promising results were seen with trastuzumab-emtansine (T-DM1), with responses correlating with the levels of HER2 protein expression by immunohistochemistry (IHC), but the latter was still regarded as a rather insufficient predictive biomarker [20,21,22]. The gene discussed is ERBB2; the disease is non-small cell lung carcinoma.