To provide a pharmaceutical composition for treating pancreatic cancer, in particular, KRAS G12C mutation-positive pancreatic cancer. The present inventors have examined compounds having G12C mutation KRAS inhibitory effect. As a result, the present inventors have confirmed that specific quinazoline compounds have G12C mutation KRAS inhibitory effect and a pharmaceutical composition comprising such a compound as an active ingredient has a therapeutic effect on pancreatic cancer, in particular, KRAS G12C mutation-positive pancreatic cancer to thereby complete the present invention.[課題]提供一種胰臟癌，特別是KRAS G12C突變陽性胰臟癌之治療用醫藥組成物。[解決手段]本發明者們探討關於具有G12C突變KRAS抑制作用之化合物，確認了特定之喹唑啉化合物具有G12C突變KRAS抑制作用，含有此等之化合物作為有效成分之醫藥組成物，對於胰臟癌，特別是KRAS G12C突變陽性胰臟癌具有治療效果，完成了本發明。
