– (R)-Afatinib ((R)-BIBW 2992), an isomer of Afatinib, is a potent, orally administered, irreversible inhibitor targeting the ErbB family (EGFR and HER2) with IC50 values of 0.5 nM for EGFR wt, 0.4 nM for EGFR L858R, 10 nM for EGFR L858R/T790M, and 14 nM for HER2, holding potential for research into esophageal squamous cell carcinoma (ESCC), non-small cell lung cancer (NSCLC), and gastric cancer [1].