COMPARATIVE-EVALUATION OF CISPLATIN AND CARBOPLATIN SENSITIVITY IN ENDOMETRIAL ADENOCARCINOMA CELL-LINES

Platinum analogues are frequently used in the treatment of advanced or recurrent endometrial cancer. To study the sensitivity of endometrial cancer to cisplatin and carboplatin, we tested two long-established ( RL95-2, KLE) and six new cell lines (UM-EC-1, UM-EC-2, UM-EC-3, UT-EC- 2A, UT-EC-2B, UT-EC-3) using the 96-well-plate clonogenic assay. This assay has proven to be suitable for testing chemosensitivity of both a denocarcinoma and squamous cell carcinoma. The chemosensitivity was ex pressed as an IC50 value, the drug concentration causing 50% inhibitio n of clonogenic survival. IC50 values were obtained from dose-response curves after fitting the data by the linear quadratic equation, F = e xp[-(alpha D + beta D-2)]. The IC50 values of the two platinum derivat ives varied considerably. The values for cisplatin varied between 0.02 2 mu g ml(-1) and 0.56 mu g ml(-1) and the corresponding values for ca rboplatin were 0.096-1.20 mu g ml(-1). The range of the ratios between carboplatin IC50 and cisplatin IC50, from 1.5:1 to 4.4:1, was rather narrow. However, no constant ratio between carboplatin IC50 and cispla tin IC50 could be detected. The equivalent doses with regard to effica cy of these two platinum analogues remain to be determined.