Neoadjuvant chemotherapy with gemcitabine and S-1 for resectable and borderline pancreatic ductal adenocarcinoma: results from a prospective multi-institutional phase 2 trial.

Background: 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.

Methods: 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.

Results: 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).

Conclusions: 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.