Class III β-tubulin overexpression is a marker of poor clinical outcome in advanced ovarian cancer patients

Purpose: Overexpression of beta III tubulin has been involved in paclitaxel resistance in several experimental models. We investigated the role of beta III tubulin as predictor of clinical outcome in ovarian cancer patients given platinum/paclitaxel treatment. We also investigated whether beta III tubulin expression could be modified after the selective pressure represented by chemotherapy in vivo. Experimental Design: The study was designed to include a series of consecutive ovarian cancer patients with unresectable disease at time of first surgery, who underwent interval debulking surgery with pathologic assessment of response to treatment with platinum/ paclitaxel chemotherapy. Immunostaining was done on formalin-fixed, paraffin-embedded tissue sections from pretreatment and posttreatment tissue biopsies by using the polyclonal rabbit anti-class III beta-tubulin antibody. Results: beta III Tubulin immunoreaction was observed in 51 of 62 (82.2%) cases. beta III Tubulin positivity was neither associated with clinicopathologic variables nor with pathologic response to chemotherapy. Significantly lower percentages of beta III tubulin positivity were observed in posttreatment (range, 5-80%; median, 20%) versus pretreatment (range 10-100%; median, 40%) tissue biopsies (P = 0.0011). Cases with high beta III tubulin expression showed a worse overall survival with respect to cases with low beta III tubulin expression (median overall survival, 25 versus 46 months; P = 0.002). Multivariate analysis showed that high content of beta III tubulin remains independently associated with a worse prognosis. Conclusions: Assessment of beta III tubulin could be useful to identify poor prognosis ovarian cancer patients candidates to more aggressive and/or targeted therapy.