Radiobiological effects of docetaxel (Taxotere): a potential radiation sensitizer

Purpose: To investigate the ability of docetaxel (Taxotere) to radiosensiti ze human cell lines of differing malignant status, intrinsic radiosensitivi ty and p53 status. Materials and methods: Cell survival following treatment with drug and/or r adiation was determined by colony-forming assay on two malignant human colo n cell lines of widely different radio-sensitivity (HT29 and SW48). An immo rtal human keratinocyte line (HaCaT), which does not form tumours in nude m ice, was used to assess the effect on non-malignant human epithelium. Results: The experiments indicate that docetaxel had the greatest cytotoxic and radiosensitizing effect on the SW48 (p53(wt)) cell line. The degree of radiosensitization was not improved by increasing the drug concentration, although the overall cytotoxicity was increased with increasing concentrati ons of the two agents. Both p53(mut) lines were less sensitive to the drug, irrespective of their malignant potential. Conclusion: The results support a role for Taxotere as a weak radiosensitiz er of the three cell lines tested. The p53 status and intrinsic radiosensit ivity may be relevant to the mechanism.