Human epidermal growth factor receptor 2 (HER2) amplification or activating mutations are found in 1.6%–4% of non-small cell lung cancer (NSCLC). Pyrotinib has been reported to have better potency in NSCLC patients with HER2 exon 20 insertion (ex20ins) mutations; however, more clinical evidence is urgently needed to guide pyrotinib-based therapy in NSCLC with HER2 amplification or heterogeneous mutations. We retrospectively analyzed advanced NSCLC patients with HER2 amplification or mutations who were treated with pyrotinib-based therapy between September 25, 2018 and October 30, 2020 in our hospital. Molecular dynamics simulation was used to explore the bioactive conformation and binding mechanisms of pan-ErbB tyrosine kinase inhibitors (TKIs) including pyrotinib for different HER2 ex20ins variants. In this study, 79 eligible patients were included with 70 ex20ins variants, 6 missense mutations and 3 primary HER2 amplifications identified. A775_G776insYVMA insertion was the most common observed subtype. The median progression-free survival (mPFS) was 5.8 (95% CI: 4.1–7.4) months. Use of pyrotinib-based therapy in first-/second-line settings showed a significantly better prognosis than that observed in third-line settings or above (mPFS: 9.1 vs. 4.4 months; P = 0.0003). Compared with HER2 amplification and exon 20 non-YVMA insertion variants, patients with HER2 missense mutations had a visible mPFS benefit (12.2 vs. 6.8 vs. 5.2 months). Computational docking simulations revealed that pyrotinib failed to interact with the specific insertion variant P780_Y781insGSP. These results indicated that pyrotinib-based therapy exhibited good anti-tumor activity and acceptable safety profile in HER2-altered advanced NSCLC.
