Evaluation of S100A4 mRNA in EUS-FNA specimens for the assessment of chemosensitivity to gemcitabine from patients with unresectable pancreatic cancer

Background/Aims: Gemcitabine (GEM) is the first-line chemotherapy in patients with unresectable pancreatic cancer. However, the clinical outcomes of this regimen are still unsatisfactory in prolonging survival. Resistant to GEM is one of the reasons for poor prognosis. Therefore, looking for molecular biomarkers to predict chemosensitivity to GEM is important for treatment in unresectable pancreatic cancer patients. The aim of this study was to analyze S100A4 mRNA in tissues of unresectable pancreatic cancer obtained by endoscopic ultrasound-guided fine-needle aspiration biopsy (EUS-FNA), and to determine the relation between S100A4 mRNA level and chemosensitivity to GEM. Methods: The analysis was performed on samples from 36 patients with unresectable pancreatic cancer who were treated with gemcitabine alone. The patients were assigned to receive GEM at 1,000 mg/m²/wk for weeks 1 to 6, followed by 1 week rest, then for 4 weeks. mRNA was extracted for S100A4 mRNA assay from patients above by EUS-FNA before GEM-treatment. The 36 patients were divided into the following two groups. Patients with partial response and those with stable disease whose tumor markers decreased by 50% or more were classified as the effective group. The rest of patients were classified as the non effective group. The relationship between GEM efficacy and S100A4 mRNA expression was then examined by chi-squared test. Results: S100A4 mRNA showed a significant correlation with GEM efficacy. Patients in the effective group had low S100A4 mRNA expression, whereas patients in non-effective group had high S100A4 mRNA expressions (P = 0.0059). Conclusion: S100A4 mRNA level analyzed in EUS-FNA samples is an important molecular biomarker for prediction of chemosensitivity to GEM in unresectable pancreatic cancer.