A new chemosensitivity test using a thermo-reversible gelation polymer for recurrent gynecologic cancer patients and a preliminary study of mechanisms of anticancer drug resistance

OBJECTIVES: TGP (thermo-reversible gelation polymer) is a high molecular compound that has so-gel transmitting temperature of 221C Since solid cancer tissue grows in this polymer three-dimensionally, and fibroblasts scarcely grow in it, TGP is suitable for chemosensitivity assays for solid tumors. In this study, a chemosensitivity test using TGP was applied to recurrent gynecologic cancer patients in order to evaluate its utility and efficacy. In some ovarian cancer cases, expression of anticancer drug resistance-related proteins was also analyzed. METHODS: Recurrent tumor tissues were surgically obtained with informed consent. After these tissues were minced and incubated for 4 days with CDDP, mitomycin C, 5-fluorouracil, paclitaxel, and CPT-11, the sensitivity against these drugs was estimated. Western blotting was performed in 8 recurrent ovarian cancer tissues in order to analyze the expression of Bcl-2, MRP2, BCRP, and GST-pi. RESULTS: The total evaluability rate of this assay was 90.6% (29/32). Sensitive drugs could be determined in 5 of 7 ascites samples (71.4%) and in 2 of 3 intra-tumoral fluid samples (66.7%). The overall clinical response rate of chemotherapy determined by these results was 50.0%. There were significant correlations between the IC50 of CDDP and Bcl-2, BCRP, GST-pi, and between that of 5-FU and MRP 2. CONCLUSIONS: Although this was a preliminary study, the chemosensitivity test using this new material appears to be useful for designing 'made-to order' salvage chemotherapy for pretreated recurrent gynecologic patients. In order to overcome multidrug resistance, the mechanisms of multidrug resistance should be further investigated.