Previously we used this approach to establish biomarkers of trastuzumab response in metastatic/recurrent HER2-positive breast cancers (Sorokin et al., 2020a), ramucirumab response in gastric cancer (Sorokin et al., 2020d), and for building gene signature for ganglioside GD2 expression in cancer cells (Sorokin et al., 2020c). The gene discussed is ERBB2; the disease is gastric cancer.