Rapid assays for evaluating the drug sensitivity of tumor cells

Assays that assess the ability of cells to incorporate labeled precursors into acid-precipitable material in the presence of adriamycin, daunorubicin, puromycin, vinblastine, melphalan, or methotrexate were investigated as an approach to the detection of resistant cells in human tumor samples. Each assay was evaluated with suitable drug-resistant Chinese hamster ovary cell lines and normal human fibroblasts to determine whether the assays reflected the drug sensitivity of these lines. Moreover, the ability to detect the presence of drug-resistance cells in a mixed population was evaluated. Validated assays were then used to measure the drug sensitivity of cell samples from pleural and peritoneal effusions of patients, mainly with carcinoma of the breast or ovary. Though the responsiveness of the majority of the samples in these assays was similar to that of a human fetal lung fibroblast line, 37 of 142 samples displayed responses consistent with the presence of a significant proportion of drug-resistant cells. Of these 37 nonresponsive samples, 12 displayed nonresponsiveness to three drugs.