Application of the adenosine triphosphate-cell viability assay in human breast cancer chemosensitivity testing: a report on the first results.

Chemosensitivity testing in vitro of breast cancer has been difficult because of small tumour volume, an even smaller yield of viable cells after disaggregation, and the low evaluability rate and sensitivity of current assays. We have employed an alternative approach that quantitates intracellular adenosine triphosphate (ATP) as a measure of cell viability. This ATP-cell viability assay (ATP-CVA) determines in vitro tumor cell viability after exposure to chemotherapeutic agents in comparison to untreated controls following 6 days of incubation. Sixty-one fresh breast cancer specimens upon testing yielded an evaluability rate of 95%. Forty-seven of the tumors were untreated primary breast cancers, the remaining 14 were from patients with metastatic disease. Correlations of in vitro drug sensitivity with in vivo response were obtained for 17 treatment regimens in 14 patients with metastatic breast cancer. The level of sensitivity was 90% and the specificity 86%. These preliminary data demonstrated the ATP-CVA to be a practical in vitro approach to breast cancer testing. It will require a larger clinical study for confirmation.