A prospective open label, multicenter phase 2 trial of full-dose gemcitabine and S-1 concurrent with radiation for locally advanced pancreatic ductal adenocarcinoma (BR + UR-LA) (CSGO-HBP-008).

PURPOSE: This prospective single-arm multicenter phase 2 trial investigated the efficacy and safety of chemoradiotherapy with gemcitabine (GEM) + S-1 (GSRT) in patients with locally advanced pancreatic ductal adenocarcinoma (PDAC) (BR + UR-LA). METHODS: Forty patients with locally advanced PDAC based on imaging findings were enrolled at three high-volume centers in Japan (April 2013-December 2018). The patient received full-dose GSRT concurrent with 50.4 Gy of radiation therapy. After chemoradiotherapy completion, the patients were reevaluated for surgical eligibility, and resection was performed if the tumors were considered resectable. In patients with unresectable tumors, chemotherapy was continued for over 6 months, and resection was performed if the tumors were considered resectable during the treatment course. The primary endpoint was the 1-year survival rate. RESULTS: Thirty-nine patients received GSRT, and their 1-year survival rate, median overall survival time, and median progression-free survival time were 64.1%, 16.6 months, and 8.7 months, respectively. Twelve patients underwent radical resection, and their 1-year survival rate, median overall survival time, and median survival time were 91.7%, 44.3 months, and 11.6 months, respectively. The response and disease control rates were 25.6% and 79.5%, respectively. The GSRT completion rate was 95%, and adverse events were well tolerated. CONCLUSIONS: GSRT is a safe and effective treatment for patients with locally advanced PDAC. TRIAL REGISTRATION: This study was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR: Registry No. UMIN 000011453).