Effect of combined use of anticancer drugs with a polysaccharide preparation, Krestin, on mouse leukemia P388.

When CDF1 mice inoculated intraperitoneally with leukemia P388 were treated intraperitoneally with mitomycin-C, of which dose was not so effective, on day 1 and given intraperitoneally polysaccharide preparation, Krestin, on day 2, 5, or 8 after tumor inoculation, best therapeutic results judged from 60-day survivors were obtained by combined use of mitomycin-C on day 1 and Krestin on day 5. Besides mitomycin-C, none of anticancer drugs such as cyclophosphamide, 5-fluorouracil, and 6-mercaptopurine was effective in this system. From these results, it was concluded that in this system, enhancement of anti-tumor effect of mitomycin-C by Krestin depends on the time of Krestin administration and that the combination effect is observed with mitomycin-C but not with cyclophosphamide, 5-fluorouracil, or 6-mercaptopurine.