Interleukin-1 alpha significantly potentiated the cytotoxicity of carboplatin (8-fold) and camptothecin (4-fold) during simultaneous drug exposure in human ovarian NIH: OVCAR-3 cancer cells in vitro. Treatment of human ovarian tumor cells grown as xenografts in nude mice with IL-1 alpha followed by either carboplatin or CTP-11 at minimally toxic doses significantly (2-3-fold and 7-fold for carboplatin and CTP-11, respectively) enhanced antitumor activity of either agent alone, indicating that IL-1-alpha-drug combinations may be potentially more effective for the treatment of ovarian tumors, including those difficult to cure in the clinic.