Oxythiamine chloride HCl is a thiamine antimetabolite that has anticancer activities. It is converted by thiamine pyrophosphokinase to oxythiamine pyrophosphate, a transketolase inhibitor. Oxythiamine decreases transketolase activity in breast cancer. It inhibits the nonoxidative synthesis of ribose and decreases RNA and DNA synthesis in pancreatic cancer. In vivo, oxythiamine induces cell cycle arrest at the G1 phase and apoptosis in an adenocarcinoma model. Oxythiamine, in combination with sorafenib, reduces tumor growth in an SMMC mouse xenograft model and has also been used to induce thiamine deficiency in mice.