A drug containing, as an active ingredient, a compound represented by ALK inhibitors such as brigatinib, AP26113-analog, and AZD3463 has been found to be effective against a non-small cell lung cancer having a point mutation at C797S in EGFR which has acquired a resistance to chemotherapy agents. Further, the drug used in combination with an anti-EGFR antibody demonstrates a notable suppression effect on the tumor growth. The drug has a potential to be a therapeutic agent effective against a non-small cell lung cancer which is resistant to gefitinib, a first generation therapeutic agent and osimertinib, a third generation therapeutic agent.
