PROBLEM TO BE SOLVED: To provide a novel cancer therapeutic agent or preventive agent for tumors which have a RET gene abnormality, particularly a secondary mutation in a fusion gene of a RET gene and other genes, and are refractory to RET inhibitors except alectinib and the like, or resistant to such RET inhibitors.SOLUTION: The invention provides a therapeutic agent or a preventive agent containing as active ingredients a compound (alectinib) and the like represented by formula (II) for tumors which have a RET gene abnormality and are refractory to RET inhibitors except the compound or resistant to such RET inhibitors, or for the metastasis of the tumors.SELECTED DRAWING: Figure 2COPYRIGHT: (C)2016,JPO&INPIT【課題】RET遺伝子異常、特にRET遺伝子と他の遺伝子との融合遺伝子に二次的変異を有する腫瘍であって、アレクチニブ等以外のRET阻害薬が無効又はかかるRET阻害薬に耐性の腫瘍に対する新規な癌治療剤又は予防剤。【解決手段】式(II)で表される化合物(アレクチニブ)等を有効成分として含有する、RET遺伝子異常を有する腫瘍であって、前記化合物を除いたRET阻害薬が無効若しくはかかるRET阻害薬に耐性を有する腫瘍、又は前記腫瘍の転移に対する治療剤又は予防剤。【選択図】図2
