(R)-Afatinib ((R)-BIBW 2992) is the Afatinib isomer. Afatinib is an orally active, potent and irreversible dual specificity inhibitor of ErbB family ( EGFR and HER2 ), with IC 50 values of 0.5 nM, 0.4 nM, 10 nM and 14 nM for EGFR wt , EGFR L858R , EGFR L858R/T790M and HER2, respectively. Afatinib can be used for the research of esophageal squamous cell carcinoma (ESCC), non-small cell lung cancer (NSCLC) and gastric cancer.