[Effects of combination chemotherapy of MCNU with various anti-cancer agents]

Combination chemotherapy using the water-soluble nitrosourea MCNU with various anti-cancer agents was studied using L1210 leukemia and P388 leukemia. In titration experiments MCNU showed remarkable antitumor effects at doses from 5 mg/kg to 80 mg/kg, producing numbers of 60-day survivors with L1210 leukemia. In L1210 leukemia, respective combinations of MCNU with the antimetabolites, MTX, 6-MP, 6-TG, MCNU, 5-FU and Cyclo-C showed enhanced antitumor effects. MCNU combined with each of ADR, MMC and CPM also showed marked anti-tumor effects with 60-day survivors. In P388 leukemia MCNU combined with each of ADR, MMC, VDS and CPM produced strong anti-tumor effects with numbers of 60-day survivors. In the results of these combinations, especially the combinations of MCNU + 5-FU in L1210 leukemia and MCNU + CPM in both L1210 and P388 leukemia, a significant increase in mean survival time was achieved. These combinations also produced many 60-day survivors which were considered to be due to the synergistic antitumor effects of the combined drugs.