A comparison of three assays used for the in vitro chemosensitivity testing of human tumours

In this study cell lines have been used to determine the level of correlation between three assays which are in use for in vitro prediction of human tumour chemosensitivity. The methods which were compared included a clonogenic assay, a monolayer assay and a short-term biochemical assay. The results indicated that the monolayer and clonogenic assays were either directly comparable or could be made comparable by reducing the drug exposure time in the monolayer assay. The biochemical assay also gave comparable results for 3 of the 5 drugs tested. It was concluded that although the 3 assays did not produce identical dose-response curves, the assays were equally valid when used for predictive testing because selection of cut-off points which were based on retrospective correlations between in vitro sensitivity data and response data, as established by other authors, compensated for differences in sensitivity between the assays.