Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) plays a key role in one-carbon (1C) metabolism in human mitochondria, and its high expression correlates with poor survival of patients with various types of cancer. An isozyme-selective MTHFD2inhibitor is highly attractive for potential use in cancer treatment. Herein, we disclose a novel isozyme-selective MTHFD2inhibitor DS44960156, with a tricyclic coumarin