Identification of synergistic combinations of spirogermanium with 5-fluorouracil or cisplatin using a range of human tumour cell lines in vitro

A series of continuous human tumour cell lines, derived from various tumour types, were used to establish whether the combination of spirogermanium (SP) with other 'standard' antitumour drugs proved superior to these as single agents in reducing cell survival in vitro. A non-cytotoxic concentration of SP was selected and when combined with a range of concentrations of cisplatin or 5-fluorouracil (5-FU), definite synergistic cell kill was noted in all lines tested. In contrast, the combination of SP with various other antitumor drugs, including adriamycin, methotrexate and the vinca alkaloids and with X-irradiation did not enhance cytotoxicity. These pre-clinical in vitro studies suggest that benefit may accrue from combining SP with either 5-FU or cisplatin and provide a basis for their clinical evaluation in colo-rectal tumours or transitional cell cancer of the bladder, respectively.