Trimetrexate is a quinazoline derivative. It is a dihydrofolate reductase inhibitor.
It has been used with leucovorin in treating pneumocystis pneumonia.
It has been investigated for use in treating leiomyosarcoma. It is a methotrexate (MTX) analog that is active against transport-deficient MTX-resistant tumor cells that overcome the acquired and natural resistance to methotrexate. Other uses include skin lymphoma.