Provided is a compound useful for the prophylaxis or treatment of cancer.The present invention relates to a compound represented by formula (I):wherein each symbol in the formula is as defined in the specification, or a salt thereof or a prodrug thereof, which is useful for the prophylaxis or treatment of cancer.本發明係提供適用於預防或治療癌症之化合物。本發明係關於式(I)表示之化合物或其鹽或其前藥:式中,各代號係如說明書中定義,其係適用於預防或治療癌症。