Validation of the clinical predictive values of the in vitro phase II clonogenic assay in cancer of the breast and ovary.

The in vitro evaluation of new antineoplastic agents has been advocated as a method of selecting drugs for Phase I-II trials in patients. This paper is an attempt to validate, in an unbiased manner, the so-called in vitro Phase II clonogenic assay with regard to its predictive power in the clinic. Breast and ovarian cancer were chosen because of the relatively large number of drugs clinically evaluated for these diseases; 298 patients were studied. For metastatic breast cancer 12 drugs, six clinically active and six inactive, were tested. It was found that in patients without prior chemotherapy, there is an association between results in vitro and in vivo. In metastatic ovarian cancer, 11 drugs, four of which are known to be clinically inactive, were studied. The same positive association was seen for patients without prior chemotherapy. The implications of these findings are discussed.