Neoadjuvant Chemotherapy with Gemcitabine and S-1 for Resectable and Borderline Pancreatic Ductal Adenocarcinoma: Results from a Prospective Multi-institutional Phase 2 Trial

Surgical resection is the only curative strategy for pancreatic ductal adenocarcinoma (PDAC), but recurrence rates are high even after purported curative resection. First-line treatment with gemcitabine and S-1 (GS) is associated with promising antitumor activity with a high response rate. The aim of this study was to assess the feasibility and efficacy of GS in the neoadjuvant setting. In a multi-institutional single-arm phase 2 study, neoadjuvant chemotherapy (NAC) with gemcitabine and S-1, repeated every 21 days, was administered for two cycles (NAC-GS) to patients with resectable and borderline PDAC. The primary end point was the 2-year survival rate. Secondary end points were feasibility, resection rate, pathological effect, recurrence-free survival, and tumor marker status. Of 36 patients enrolled, 35 were eligible for this clinical trial conducted between 2008 and 2010. The most common toxicity was neutropenia in response to 90 % of the relative dose intensity. Responses to NAC included radiological tumor shrinkage (69 %) and decreases in CA19-9 levels (89 %). R0 resection was performed for 87 % in resection, and the morbidity rate (40 %) was acceptable. The 2-year survival rate of the total cohort was 45.7 %. Patients who underwent resection without metastases after NAC-GS (n = 27) had an increased median overall survival (34.7 months) compared with those who did not undergo resection (P = 0.0017). NAC-GS was well tolerated and safe when used in a multi-institutional setting. The R0 resection rate and the 2-year survival rate analysis are encouraging for patients with resectable and borderline PDAC.