ERBB2 and esophageal squamous cell carcinoma: We next evaluated our panel of ESCC models for their in vitro sensitivity to erlotinib, a reversible small-molecule EGFR inhibitor, and afatinib, an irreversible small-molecule EGFR/ERBB2 inhibitor, finding a range of sensitivities (Fig. 1c and Supplementary Table 1).