Interaction between amphotericin B, carboplatin, and radiation in human osteosarcoma xenografts in nude mice

In order to evaluate and modify the radiosensitizing effect of carboplatin, amphotericin B (AmB) was given as pre-treatment to nude mice with bilateral subcutaneous human osteosarcoma xenografts. One of the two tumours in each animal was irradiated with a single dose of 12 Gy following treatment with AmB (5 mg kg(-1)), or carboplatin (20 mg kg(-1)), or AmB (5 mg kg(-1)) plus carboplatin (20 mg kg(-1)), respectively. Tumour growth was compared with non-treated tumours. A significant reduction of tumour growth was observed after irradiation. Carboplatin in itself reduced tumour growth and also added to the effect of radiation. An unexpected interaction was seen where AmB obviously decreased the effect of either carboplatin or radiation alone or the two given concomitantly. The presented results are contradictory to some earlier in vitro studies and imply that the interactive effect in general and especially with regard to AmB can not be universally applied to all experimental situations.