Afatinib was evaluated in a compassionate use program in heavily pretreated patients with HER2-mutant NSCLC and showed a median time-to-treatment failure (TTF) of 2.9 months, with interesting variations among subtypes; notably, the HER2 exon 20 YVMA insertion subtype showed a median TTF of 9.6 months [27]. The gene discussed is ERBB2; the disease is non-small cell lung carcinoma.