The present inventors successfully produced therapeutic agents for non-small cell lung cancer except adenocarcinoma, comprising as active ingredient an anti-Epiregulin antibody that shows cross-species reactivity between the human animal and cynomolgus which is a non-human animal, an anti-Epiregulin antibody with suppressed chemical degradation, an anti-Epiregulin antibody with reduced isoelectric point, an anti-Epiregulin antibody with increased midpoint temperature of thermal denaturation, or an anti-Epiregulin antibody with reduced amount of aggregates, generated by appropriately substituting amino acid residues in the variable-region sequences of a humanized EP27 antibody that inhibits cancer cell proliferation by exerting a cytotoxicity and a neutralizing activity against human Epiregulin-expressing cancer cells.
