The comparable TMB between HER2-mutated and HER2-amplified NSCLC in late-stage disease was likely due to the increased tumor mutation load of late-stage HER2-mutated tumors, as indicated by our results that in HER2-mutated NSCLC, patients with late-stage disease had higher TMB than those with early-stage disease. The gene discussed is ERBB2; the disease is non-small cell lung carcinoma.