Chemosensitivity testing of irinotecan (CPT-11) in ovarian and endometrialcarcinomas: a comparison with cisplatin

Background: The tetrazolium dye (MTT) assay is useful in predicting chemose nsitivity. Materials and Methods. Using an MTT assay, we designed an in vit ro chemosensitivity test for irinotecan (CPT-11) and compared if with sensi tivity to cisplatin in gynecologic carcinomas removed from 49 patients. Res ults: The mean tumor inhibition rate (I.R.: %) for irinotecan was relativel y inferior to the I.R. for cisplatin in both ovarian and endometrial carcin omas [40.2 vs 53.2 and 43.5 vs 58.0] (p < 0.05, respectively). In ovarian c arcinomas, 13 (48.1%) of 27 cases were irinotecan-sensitive (I.R. greater t han or equal to 50%) and 77% of the tumors were judged to be irinotecan and /or cisplatin-sensitive. There was no significant difference in the I.R. fo r irinotecan among the various histologic subtypes. Comparing in vitro sens itivity to irinotecan with clinical responses in 8 patients who received ir inotecan, the overall accuracy of the MTT assay far evaluating clinical eff ectiveness was 75% (6 out of 8). In endometrial carcinomas, we found 9 (40. 9%) out of 22 cases to be irinotecan-sensitive. The I.R. for irinotecan in G1 carcinomas [33.5] was significantly lower than in G2 carcinomas [59.3] ( p < 0.05). Conclusion: Our data suggest that irinotecan appears to have mod erate antitumor activity in vitro against both ovarian and endometrial carc inomas and that differences in irinotecan sensitivity among the histologic subtypes were evident in the fatter but not in the former.