In vitro growth characteristics and chemosensitivities of endometrial cancer using a soft agar clonogenic assay

A soft agar clonogenic assay was used to analyze 91 fresh human endometrial tumor samples for in vitro growth and chemosensitivities. Overall cloning success was 81%. Of the 75 samples adequate for drug testing (30 or more colonies per plate), histologic analysis demonstrated 36 adenocarcinomas, seven adenoacanthomas, ten adenosquamous carcinomas, nine mixed mesodermal sarcomas, seven carcinosarcomas, three papillary adenocarcinomas, and three clear-cell carcinomas. Mixed mesodermal sarcoma specimens demonstrated the most efficient growth, followed by the adenosquamous adenocarcinoma and adenoacanthoma samples. In vitro chemosensitivities were determined by colony inhibition resulting from continuous exposure of tumor cells to known achievable peak plasma and one-tenth peak plasma concentrations of a particular agent. The plating efficiency reflected the clinical virulence by cell type. Thus, we found that malignant endometrial tumors can be cloned in vitro, and the observed chemosensitivities reflect the relative clinical resistance of the tumors to these agents. Based on the high cloning success, this tumor type may be well suited as a model using in vitro soft agar cloning for new drug screening, evaluation of novel drug combinations, and studies of human tumor biology.