While RFC, TOPO1 and TOPO2A have not been specifically validated in EC patients, based on biochemical mechanisms of action, it would be valuable to consider multiplexed molecular diagnostics to identify the status of these tumor targets along with the three validated resistance markers (ERCC1, TUBB3, TS) and the three antibody-based therapy targets (HER2, EGFR, PD-L1) in an effort to augment first-line therapy choices (Figure 4). The gene discussed is ERBB2; the disease is neoplasm.