The absence of class III β-tubulin is predictive of a favorable response to nab-paclitaxel and gemcitabine in patients with unresectable pancreatic ductal adenocarcinoma

The combined administration of nab-paclitaxel and gemcitabine (nab-P + Gem) is a standard chemotherapy for unresectable pancreatic ductal adenocarcinoma (UR-PDAC); thus, a predictive biomarker to identify patients best suited for nab-P + Gem therapy would be useful. Class III β-tubulin (TUBB3) has been reported to be a predictive marker for taxane resistance in various tumors. However, the correlation between TUBB3 expression and the response to nab-P + Gem in patients with UR-PDAC has not been evaluated. We retrospectively reviewed 75 patients with UR-PDAC who received nab-P + Gem. TUBB3 expression was examined immunohistochemically in specimens obtained by endoscopic ultrasound-guided fine needle aspiration (EUS-FNA). From 67 analyzable specimens that were available for TUBB3 staining, 14 (21%) were negative for TUBB3 immunostaining and 53 (79%) were positive. Patients with negative TUBB3 expression showed a significantly higher disease control rate (100% vs. 64.2%; P = .008) and longer progression-free survival (PFS); (7.1 months vs. 3.7 months; log-rank test, P = .036) than those of patients with positive. Furthermore, negative TUBB3 expression was an independent predictive marker of a prolonged PFS on multivariate analysis (hazard ratio, 2.41; 95% confidence interval, 1.11-5.24; P = .026). Our data indicate that an absence of TUBB3 expression in specimens obtained by EUS-FNA may be a favorable predictive marker of the response to nab-P + Gem in patients with UR-PDAC, highlighting its use as a potential new biomarker for treatment optimization.