ABSTRACT
PURPOSE: Immunotherapies have shown limited responses in patients with advanced pancreatic cancer. Recently, we reported that dendritic cell (DC)-based immunotherapy induced T-cell responses against pancreatic cancer antigens. The primary objective of this study was to determine the efficacy of DC-based immunotherapy to prevent recurrence of disease. METHODS: This was a single-center, open-label, single-arm, combined phase I/II trial. The primary end point was the 2-year recurrence-free survival (RFS) rate. A 2-year RFS rate of ≥60% was defined as a clinically meaningful improvement. We included patients with pancreatic cancer after resection and completion of standard-of-care (SOC) treatment without recurrent disease on cross-sectional imaging. Patients were treated with autologous DCs pulsed with an allogeneic mesothelioma tumor cell lysate, comprising antigens also expressed in pancreatic ductal adenocarcinoma. RESULTS: Thirty-eight patients were included in the analysis of the primary end point (47% male, 53% female). The median age was 62 years (IQR, 55-68). Twenty-eight patients (74%) received five DC vaccinations and completed the study protocol. Three patients (8%) received four vaccinations, and seven patients (16%) received three vaccinations. After a median follow-up of 25.5 months, 26 patients (68%) had not developed recurrence of disease. The estimated 2-year RFS was 64%. Vaccination led to the enrichment of circulating activated CD4+ T cells and the detection of treatment-induced immune responses in vitro. T-cell receptor-sequencing analyses of a resected solitary lung metastasis showed influx of vaccine-specific T cells. CONCLUSION: This study reached its primary end point of a 2-year RFS rate of ≥60% following pancreatectomy after SOC treatment and adjuvant DC-based immunotherapy in patients with pancreatic cancer. These results warrant a future randomized trial.
ABSTRACT
Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest solid tumors and is resistant to immunotherapy. B cells play an essential role in PDAC progression and immune responses, both locally and systemically. Moreover, increasing evidence suggests that microbial compositions inside the tumor, as well as in the oral cavity and the gut, are important factors in shaping the PDAC immune landscape. However, the gut-associated lymphoid tissue (GALT) has not previously been explored in PDAC patients. In this study, we analyzed healthy vermiform appendix (VA) from 20 patients with PDAC and 32 patients with colon diseases by gene expression immune profiling, flow cytometry analysis, and microbiome sequencing. We show that the VA GALT of PDAC patients exhibits markers of increased inflammation and cytotoxic cell activity. In contrast, B cell function is decreased in PDAC VA GALT based on gene expression profiling; B cells express significantly fewer MHC class II surface receptors, whereas plasma cells express the immune checkpoint molecule HLA-G. Additionally, the vermiform appendix microbiome of PDAC patients is enriched with Klebsiella pneumoniae, Bifidobacterium animalis, and Adlercreutzia equolifaciens, while certain commensals are depleted. Our findings may suggest impaired B cell function within the GALT of PDAC patients, which could potentially be linked to microbial dysbiosis. Additional investigations are imperative to validate our observations and explore these potential targets of future therapies.
