Aminopterin is a synthetic derivative of pterins with antineoplastic and immunosuppressive properties. As a folate analog, aminopterin competes for the folate binding site of the enzyme dihydrofolate reductase, thereby blocking tetrahydrofolate synthesis, and resulting in depletion of nucleotide precursors and inhibition of DNA, RNA and protein synthesis. Aminopterin was marketed by Lederle Laboratories (Pearl River, New York) in the United States from 1953 to 1964 for the indication of pediatric leukemia. The closely related antifolate methotrexate was simultaneously marketed by the company during the same period. Aminopterin was discontinued by Lederle Laboratories in favor of methotrexate due to manufacturing difficulties of the former. During the period Aminopterin was marketed, the agent was used off-label to safely treat over 4,000 patients with psoriasis in the United States, producing dramatic clearing of lesions. The use of aminopterin in cancer treatment was supplanted in the 1950s by methotrexate due to the latter's better therapeutic index in a rodent tumor model. Now in a more pure preparation and supported by laboratory evidence of superior tumor cell uptake in vitro, aminopterin is being investigated in clinical trials in leukemia as a potentially superior antifolate to methotrexate.

Cridanimod (Virexxa) is a small-molecule immunomodulator and interferon inducer, which, in preliminary studies, has been shown to increase progesterone receptor expression in endometrial tissue. Restoration of progesterone receptor expression may re-sensitize endometrial tumor tissue to progestin therapy in previously unresponsive tumors. Cridanimod was originally developed by Polysan and Pharmsynthez and licensed to Xenetic Biosciences. Virexxa is currently being studied in an ongoing Phase 2 multi-national study in conjunction with progestin therapy for the treatment of endometrial cancer in women with the recurrent or persistent disease who have failed progestin monotherapy.

Buformin (1-butylbiguanide) is an oral antidiabetic drug of the biguanide class. AMPK activator. AMPK is a potential therapeutic target in the prevention and the treatment of type 2 diabetes and insulin resistance. Major classes of antidiabetic drugs have been reported to activate AMPK. Buformin exerts its anti-tumorigenic activity via activation of AMPK and inhibition of the mTOR signaling pathways in endometrial cancer cells. Toxicity: guinea pig LD50 subcutaneous 18 mg/kg; mouse LD50 intraperitoneal 140 mg/kg and 300 mg/kg oral. Buformin was withdrawn from the market in many countries due to an elevated risk of causing lactic acidosis.

Gestonorone is a progesterone analogue indicated for the treatment of benign prostatic hyperplasia and endometrial cancer. The drug is approved in many countries and used under the names Primostat and Depostat.