Phase II clinical trial using novel peptide cocktail vaccine as a postoperative adjuvant treatment for surgically resected pancreatic cancer patients

We investigated peptide cocktail vaccine OCV-C01 containing epitope peptides derived from KIF20A, vascular endothelial growth factor receptor (VEGFR)1 and VEGFR2 combined with gemcitabine in the adjuvant treatment for resected pancreatic cancer patients. A single-arm multicenter phase II study was performed on 30 patients with pancreatic ductal carcinoma who underwent pancreatectomy. At each 28-day treatment cycle, patients received weekly subcutaneous injection of OCV-C01 for 48 weeks and gemcitabine was administered intravenously at 1,000 mg/m2 on days 1, 8 and 15 for 24 weeks. Patients were followed for 18 months. The primary endpoint was disease-free survival (DFS) and secondary endpoints included safety, overall survival (OS) and immunological assays on peptide-specific cytotoxic T lymphocyte (CTL) activity and KIF20A expression in resected pancreatic cancer. The median DFS was 15.8 months [95% confidence interval (CI), 11.1–20.6] and the DFS rate at 18 months was 34.6% (95% CI, 18.3–51.6). The median OS was not reached and the OS rate at 18 months was 69.0% (95% CI, 48.8–82.5). The administration of OCV-C01 was well tolerated. In the per protocol set, there were significant differences in DFS between patients with KIF20A-specific CTL responses and without (p = 0.027), and between patients with KIF20A expression and without (p = 0.014). In addition, all four patients who underwent R0 resection with KIF20A expression had no recurrence of pancreatic cancer with KIF20A-specific CTL responses. OCV-C01 combined with gemcitabine was tolerable with a median DFS of 15.8 months, which was favorable compared with previous data for resected pancreatic cancer.