Prognostic factors related to add-on dendritic cell vaccines on patients with inoperable pancreatic cancer receiving chemotherapy: a multicenter analysis

Dendritic cell (DC)-based cancer vaccines may have a significant benefit to patients with advanced pancreatic cancer. However, variations among clinical studies make it difficult to compare clinical outcomes. Here, we identified factors that determined the clinical benefits by analyzing data obtained at seven Japanese institutions that employed the same DC preparation and treatment regimens. Of 354 patients who met the inclusion criteria, 255 patients who received standard chemotherapy combined with peptide-pulsed DC vaccines were analyzed. The mean survival time from diagnosis was 16.5 months (95 % CI 14.4-18.5) and that from the first vaccination was 9.9 months (95 % CI 8.0-12.9). Known prognostic baseline factors related to advanced pancreatic cancer, namely ECOG-PS, peritoneal metastasis, liver metastasis, and the prognostic nutrition index, were also representative. Importantly, we found that erythema reaction after vaccination was an independent and treatment-related prognostic factor for better survival and that OK-432 might be a good adjuvant enhancing the antitumor immunity during DC vaccination. This is the first report of a multicenter clinical study suggesting the feasibility and possible clinical benefit of an add-on DC vaccine in patients with advanced pancreatic cancer who are undergoing chemotherapy. These findings need to be addressed in well-controlled prospective randomized trials.