Limitations of drug sensitivity testing in soft agar for clinical management of patients with ovarian carcinoma.

Thirty specimens from 28 patients (15 previously treated, 13 previously untreated) with ovarian carcinoma were studied in a soft agar colony-forming assay to determine whether or not the assay could be useful for treatment planning. There were sufficient colonies for drug testing in 23 cases. An in vitro drug response was found in 12 of 106 drug tests. In vivo-in vitro correlations could be made for 28 drug trials in 16 patients. Eight patients were not evaluated for response because they were clinically disease free after debulking surgery. Single agents were evaluated in vitro, although most patients received combination chemotherapy. In 23 cases the tumor was resistant in vitro and in vivo. There were two false-negative and three false-positive results. Cell aggregates that may artificially increase growth rates and apparent in vitro drug resistance were a major problem technically. In view of the problems identified, the assay in its current form should not be used routinely to direct therapy.