PROBLEM TO BE SOLVED: To provide pyrazine derivatives useful as inhibitors of ATR protein kinase, playing an important role in the DNA damage response (DDR) of a cancer cell.SOLUTION: The invention relates to pyrazine derivatives useful as inhibitors of ATR protein kinase, represented by the following formula, having the functions to stop the DNA repair processes of cancer cells and inhibit the cellular survival of cancer cells, and useful for treatment of cancer [Y is a methylene group or the like; A is a 5 membered heterocycle or the like; Q is an aromatic ring comprising 0-4 hetero atom(s) or the like; L is an alkyl chain; R, Rand Rare H, a ring comprising a hetero atom or the like; Jis CN or the like; m, p and q are 0 or 1 and the like].SELECTED DRAWING: None【課題】癌細胞のDNA損傷応答(DDR)に重要な役割を果たす、ATRプロテインキナーゼのインヒビターとして有用なピラジン誘導体の提供。【解決手段】下記式で代表される、癌細胞のDNA修復プロセスを停止させ、癌細胞の細胞生存を阻害する機能を有する、癌の治療に有効な、ATRプロテインキナーゼのインヒビターとしてのピラジン誘導体。[Yはメチレン基等;Aは5員のヘテロ環等;Qは0~4個のヘテロ原子を含む芳香環等;Lはアルキル鎖;R1、R2及びR5はH、ヘテロ原子を含む環等;J2はCN等;m,p及びqは0又は1等]【選択図】なし