Correlation of in vitro cytotoxicity with preclinical in vivo antitumor activity

Several human and murine tumor cell lines were evaluated in an in vitro cytotoxicity assay as prescreens for fermentation extracts and pure materials subsequently tested in vivo against P388 leukemia or B16 melanoma. Each material, regardless of its in vitro cytotoxicity, was evaluated in vivo. At the criteria levels of in vitro positivity and in vivo activity invoked, a highly significant relationship between these two endpoints was demonstrated for each cell line. When cell lines were compared, most of them performed in a similar manner, with HCT-116 human colon carcinoma cells providing a modest advantage predicting for P388 activity in some comparisons. Using the data from any two cell lines in concert did not improve the acuity of the prescreen beyond that associated with the better cell lines used singularly and only a minority of active materials was predicted for uniquely. Overall, the in vitro cytotoxicity assay provided a useful prescreen for selecting P388 and B16 in vivo active materials.