A synthetic dihydrotriazine derivative with antineoplastic properties. As an antifolate agent related to methotrexate (MTX), triazinate inhibits the enzyme dihydrofolate reductase (DHFR), resulting in decreased tetrahydrofolate production and interference with thymidylate synthesis. Unlike MTX, this agent is not converted to polyglutamate forms. Triazinate also inhibits the transport of folates and may be selectively toxic to MTX-resistant tumor cells.