Given other known irreversible ErbB inhibitors, HKI-272, BIBW2992, CI1033, and PF-00299804 are active in both EGFR- and ErbB2-dependent tumor xenograft models [15], [19], [20], [35], [36], [37], whereas EKB569 shows poorer efficacy in ErbB2-dependent tumor modes than in EGFR-dependent models [35], our results that AST1306 is more efficacious in ErbB2- than EGFR-dependent models suggest that AST1306 is somewhat different from the known irreversible ErbB family inhibitors. This evidence concerns the gene EGFR and neoplasm.