Squamous cell carcinoma is highly sensitive to taxol, a possible new radiation sensitizer

We studied the sensitivity of seven cell lines established from laryngeal carcinoma to the cytotoxic drug paclitaxel (Taxol) in vitro. In all four cell lines tested for growth inhibition, paclitaxel reduced growth at low concentrations, and in two cell lines growth was completely inhibited at a paclitaxel concentration of only 1 x 10(-8) M. Flow cytometric data showed a G2/M block in all seven cell lines after exposure to paclitaxel for 24 h at a concentration of 1 x 10(-8) M. This concentration is about one-one hundredth fold smaller than those measured in serum after a single intravenous dose of about 200 mg/m2. The high in vitro sensitivity of laryngeal cancer cell lines to paclitaxel,and the G2/M block suggest that the drug may potentially be used in conjunction with radiotherapy.