2. チロシンキナーゼ阻害剤によるGISTの治療適応

Application of Tyrosine Kinase Inhibitor to GIST Patients

要旨　GISTにおけるimatinib mesylateの基本的な適応条件はKIT陽性であることのみだが，手術により根治可能なGIST症例に対し安易に使うべきではない．imatinibの効果はc-kit遺伝子，PDGFレセプターα遺伝子の突然変異のタイプに大きく依存しており，治療効果を予測する上でこれら遺伝子の突然変異検索は必須となる．アジュバント療法としてのimatinibの投与の有用性については，欧米などの臨床試験の結果を待って判断すべきであろう．imatinib投与中に腫瘍が再増殖した場合，耐性クローン部分を外科的に除去できれば，imatinibはその後も適応となる．

　Imatinib mesylate is allowed to be applied to KIT-positive GISTs in Japan, but it should not be indiscriminately used for surgically treatable GISTs. Since the effect of Imatinib depends on the types of mutations of c-kit gene or PDGFR αgene, an analysis of the mutation of these genes is essential to predict the patient's response to the drug. Use of Imatinib as adjuvant therapy is now being studied, so the results will give information whether its use as adjuvant therapy is required or not. In patients with regrowth of GISTs after Imatinib administration, the drug could be continuously applied if the resistant clone has been successfully removed.

　1) Division of Surgical Pathology, Osaka University Medical Hospital, Suita, Japan