An intercomparison of in vitro assays for assessing cytotoxicity after a 24 hour exposure to anti-cancer drugs.

Employing a tumourigenic mouse cell line, we have measured the effects of four anti-cancer drugs (methotrexate, vincristine, cis-platinum and adriamycin) upon tumour cell survival as assessed by three independent procedures. The results from two short-term procedures based upon dye exclusion and labeling index determinations were compared with data from the relatively long-term clonogenic or colony-forming assay. The dye exclusion procedure demonstrated the poorest correlation with the clonogenic assay, whereas labeling index measurements exhibited qualitative but not quantitative correspondence with results from the clonogenic assay. These short-term procedures cannot therefore be considered accurate substitutes for a clonogenic assay, which remains the method of choice for assessing cytotoxic effects of anti-cancer drugs.