[In vitro chemosensitivity tests of human lung small cell carcinomas--with reference to combination cancer chemotherapy].

Four human lung small cell carcinoma (SCC) cell lines were used for the experimental cancer chemotherapy with a single agent and combination method. The chemosensitivity of SCC cell lines including H-69, H-128, Lu-24 and Lu-134 were assessed by the clonogenic assay according to the method of Salmon and Humburger. Cyclophosphamide (CPA) showed the most excellent antitumor effect against these 4 strains followed by tetra-hydropyranyl adriamycin and adriamycin (ADM). In vitro combination clonogenic assay was conducted by mixing the half of the concentration of two matched drugs and the synergistic effect was evaluated according to the method of Berenbaum. Whereas the synergistic effects were frequently observed in the combination of drugs which were effective by the single usage, it was found that the combination of CPA + mitomycin C and CPA + ADM showed high efficacy rates against these cell lines in comparison with other matchings. From these findings, it was concluded that the combination chemosensitivity test in clonogenic assay might be a promising method to evaluate the chemosensitivity of the individual patient. And it was supposed that this method might be also useful as an early phase III study to predict the useful combination of newly developed antitumor agents.