The present invention relates to inhibitors of deubiquitinating enzymes, particularly ubiquitin C-terminal hydrolase 30 or ubiquitin-specific peptidase 30 (USP30), which have utility in a variety of therapeutic fields including cancer and conditions associated with mitochondrial dysfunction. Relates to cyano-substituted heterocycles of formula (I) having activity as (I)本発明は、癌及びミトコンドリア機能不全を伴う状態を含む様々な治療分野において有用性を有する、脱ユビキチン化酵素、特に、ユビキチンＣ末端加水分解酵素３０又はユビキチン特異的ペプチダーゼ３０（ＵＳＰ３０）の阻害剤としての活性を有する式（Ｉ）のシアノ置換複素環類に関する。（Ｉ）
