Potentially useful biomarkers include PD-L1, tumor mutational burden, DNA repair mutations, excision repair cross-complementing protein 1 (ERCC1) and excision repair cross-complementing protein 2 (ERCC2), FGFR mutation, EGFR expression or mutation, HER2 expression, PARP expression and circulating tumor DNA (ctDNA). The gene discussed is ERBB2; the disease is neoplasm.