Is class III beta-tubulin a true predictive marker of sensitivity to vinorelbine in non-small cell lung cancer? Chemosensitivity data evidence.

Aim: To clarify whether class III β-tubulin (TUBB3) is a true predictive marker for chemotherapy with vinorelbine, chemosensitivity was examined using an in vitro drug sensitivity assay.

Patients And Methods: Initially, 9 specimens were obtained to analyze the dose-response curve and to measure the median effective dose 50 (ED(50)) in the histoculture drug response assay (HDRA). Subsequently, 68 surgically resected non-small cell lung cancer (NSCLC) specimens were applied to the HDRA and H-scores were calculated by immunohistochemical staining.

Results: The mean (±SD) slope factor, ED(50) and maximal response was 8.7±5.4, 39.0±17.9 μg/ml and 85.5±5.1% respectively. The mean inhibition rate was 26.4±16.2% and the mean H-score was 1.09±1.07. The inhibition rate was significantly correlated with TUBB3 expression (r=0.27, p=0.03), and was significantly higher in TUBB3-positive specimens than in TUBB3-negative specimens (p=0.003).

Conclusion: Tumors with high TUBB3 levels exhibited greater chemosensitivity to vinorelbine than tumors with low TUBB3 levels. This finding provides support for the results of the JBR.10 trial.