Evaluation of Cyclophosphamide/GVAX Pancreas Followed by Listeria-mesothelin (CRS-207) With or Without Nivolumab in Patients with Pancreatic Cancer

Purpose: Two studies in previously-treated metastatic pancreatic cancer have been completed combining GVAX pancreas vaccine (granulocyte-macrophage colony-stimulating factor-secreting allogeneic pancreatic tumor cells) with cyclophosphamide (Cy) and CRS-207 (live, attenuated Listeria monocytogenes expressing mesothelin). In the current study, we compared Cy/GVAX followed by CRS-207 with (Arm A) or without nivolumab (Arm B). Experimental Design: Patients with pancreatic adenocarcinoma who received one prior therapy for metastatic disease and RECIST measurable disease were randomized 1:1 to receive treatment on Arm A or Arm B. The primary objective was to compare overall survival (OS) between the arms. Additional objectives included assessment of progression-free survival, safety, tumor responses, CA19-9 responses and immunologic correlates. Results: Ninety-three patients were treated (Arm A, 51; Arm B, 42). The median OS in Arms A and B were 5.9 (95% CI, 4.7, 8.6) and 6.1 (95% CI, 3.5, 7.0) months, respectively, with a hazard ratio 0.86 (95% CI, 0.55, 1.34). Objective responses were seen in three patients using immune-related response criteria (4%, 2/51, Arm A; 2%, 1/42, Arm B). The > grade 3 related adverse event rate while higher in Arm A (35.3% vs 11.9%) was manageable. Changes in the microenvironment, including increase in CD8+ T cells and a decrease in CD68+ myeloid cells, were observed in long-term survivors in Arm A only. Conclusions: While the study did not meet its primary endpoint of improvement in OS of Arm A over Arm B, the OS was comparable to standard therapy. Objective responses and immunologic changes in the tumor microenvironment were evident.