Class III Beta-tubulin Expression in Non-small Cell Lung Cancer: A Predictive Factor for Paclitaxel Response

Aim: In order to clarify whether class III betatubulin (TUBB3) is a predictive marker for paclitaxel (PTX) chemotherapy, chemosensitivity was examined using an in vitro drug sensitivity assay. Patients and Methods: Twelve specimens from non-small cell lung cancer (NSCLC) patients were obtained for dose-response curve analysis and measurement of the half-maximal effective dose (ED50) of PTX using the histoculture drug response assay (HDRA). Forty-one specimens were evaluated using the HDRA and the inhibition ratio (IR) at a concentration of 25 mu g/ml PTX (IR25) was measured. TUBB3 expression was evaluated by H-score in immunohistochemical staining. Results: The ED50 of PTX was 24.5 +/- 8.06 mu g/ml. The median H-score was significantly higher (p=0.0076) in the high effective dose (HE)-group (ED50 >25 mu g/ml) than in the low effective (LE)-group (ED50 <= 25 mu g/ml). The mean IR25 was 53.8 +/- 26.6%. The median H-score for the high-inhibition ratio (HI)-group (IR25 >50%) was significantly higher (p=0.0337) than the low-inhibition ratio (LI)-group (IR25 <= 50%). Conclusion: High TUBB3 expression in NSCLC appeared to correlate with lower PTX sensitivity.