[Assessment of the combined effects of mitomycin C with alpha-interferon or gamma-interferon by the clonogenic assay technique].

The combined effects of Mitomycin C (MMC) with alpha-interferon (HLBI) or gamma-interferon (TRP-2), which have become attractive drugs for use as Biological Response Modifiers, were investigated using the human tumor clonogenic assay technique. Tumors in this study were five human tumor xenografts serially transplanted into nude mice (three gastric cancer, two colon cancer). When the survival fraction occurring with the combination was smaller than that obtained by multiplication of the survival fractions occurring with either drug alone, the combined effect was considered to be synergism. Four out of five xenografts (three gastric cancer, one colon cancer) showed synergistic effects for the combination of MMC with alpha-interferon. Although two gastric cancer xenografts showed synergism for the combination of MMC with gamma-interferon, antagonistic effects were observed in one gastric cancer and one colon cancer xenograft.