ACTIVITY OF PLATINUM DRUGS AGAINST MELANOMA CELL-LINES - IS IT MODULATED IN-VITRO IN THE PRESENCE OF TAMOXIFEN

Cisplatin and carboplatin have been used against human malignant melanoma as single agents and in combination. Tamoxifen;is used in the treatment of breast cancer; but has no significant activity against human malignant melanoma. Tamoxifen, however; has been promoted as a modulator in some drug regimens. The addition of tamoxifen to cisplatin or carboplatin has been reported to enhance their activity against the human melanoma cell line T-289. We investigated whether tamoxifen potentiates, in vitro, the activity of cisplatin and carboplatin against C32, G361 and StMl11a melanoma cell fines. Tamoxifen alone at clinically achievable concentrations of 0.1 and 1.0 mu M (168 ha exposure) had no significant effect on growth. No chemopotentiation of the activity of cisplatin ol carboplatin was observed with the addition of tamoxifen (0.1 and 1.0 mu M). The platinum drugs were added for I hr (serially diluted from 100.0 mu M). Against the G361 line there was a trend towards chemopotentiation of cisplatin by 0.1 mu M of tamoxifen. However; this did not reach stastistical significance. Tamoxifen (5.0 and 10.0 mu M) produced some inhibitory activity and a trend towards synergy with cisplatin was observed. However, these concentrations are not clinically feasible. Previous reports detecting synergistic interaction between tamoxifen (0.1 and LO mu M), and the platinum compounds against the T-289 melanoma cell line cannot be supported in our in vitro system.