Clinical and immune characteristics of rapid dropout and long-term survival in a phase II safety and efficacy study of combination CRS-207/GVAX immunotherapy in pancreatic cancer.

459 Background: Baseline patient characteristics may impact duration on study and survivorship of patients in immunotherapy trials. In this study, GVAX pancreas (GM-CSF–secreting allogeneic pancreatic tumor cells) was administered with low-dose cyclophosphamide (Cy), with or without subsequent CRS-207 (live-attenuated Listeria monocytogenes–expressing mesothelin) infusion. Baseline clinical and immunological data were examined for two patient subsets based on duration on study. Methods: Previously treated patients with metastatic pancreatic adenocarcinoma were randomly assigned at a ratio of 2:1 to 2 doses of Cy/GVAX followed by 4 doses of CRS-207 or 6 doses of Cy/GVAX every 3 weeks. Stable patients were offered additional courses. Patients were evaluated for post-randomization duration on study of 18 months (long-term survivors, LTS). Baseline characteristics of these subsets were examined. Results: A total of 93 patients were randomized. Fifteen patients were RD; 13 ...