“…Metoprine (DDMP) (2,4-diammino-5-(3',4'-dichlorophenyl)-6-methylpyrimidine ( Figure 1) is a lipidsoluble inhibitor of dihydrofolate reductase that produces antitumor effects in mice (Burchenal, Goetchius & Stock, 1952;Sirotnak, Dorick & Moccio, 1976), rats (Denlinger, Cavallito & Nichol, 1976), and man (Murphy, Ellison & Kamofsky, 1954 0306-5251/81/110675406 $01.00 (Murphy et al, 1954;Alberto, Brugarolas, & DeJager, 1979;Currie, Kempin & Young, 1981;Miller, Nichol & Rundles, 1976;Pnrce, Goldie & Hill, 1975;Price & Hill, 1976;Price, Goldie & Hill, 1977). In the murine sarcoma 180 model, improvement in the therapeutic index of the DDMP has been noted with the incorporation of citrovorum-factor rescue into dosage schedules (Price & Hill, 1976); clinical studies at Memorial Hospital were conducted to evaluate this regimen in man.…”