A monocarboxylic acid amide resulting from the formal condensation of the carboxy group of 6-aminonicotinic acid with ammonia. An inhibitor of the NADP(+)-dependent enzyme, 6-phosphogluconate dehydrogenase, it interferes with glycolysis, resulting in ATP depletion and synergizes with DNA-crosslinking chemotherapy drugs, such as cisplatin, in killing cancer cells.