Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and deadliest cancer worldwide with an overall survival rate, all stages combined, of still <10% at 5 years. The poor prognosis is attributed to challenges in early detection, a low opportunity for radical resection, limited response to chemotherapy, radiotherapy, and resistance to immune therapy. Moreover, pancreatic tumoral cells are surrounded by an abundant desmoplastic stroma, which is responsible for creating a mechanical barrier, preventing appropriate vascularization and leading to poor immune cell infiltration. Accumulated evidence suggests that PDAC is impaired with multiple “immune defects”, including a lack of high-quality effector cells (CD4, CD8 T cells, dendritic cells), barriers to effector cell infiltration due to that desmoplastic reaction, and a dominance of immune cells such as regulatory T cells, myeloid-derived suppressor cells, and M2 macrophages, resulting in an immunosuppressive tumor microenvironment (TME). Although recent studies have brought new insights into PDAC immune TME, its understanding remains not fully elucidated. Further studies are required for a better understanding of human PDAC immune TME, which might help to develop potent new therapeutic strategies by correcting these immune defects with the hope to unlock the resistance to (immune) therapy. In this review, we describe the main effector immune cells and immunosuppressive actors involved in human PDAC TME, as well as their implications as potential biomarkers and therapeutic targets.

Background Whether vedolizumab may be effective as a treatment for primary sclerosing cholangitis [PSC] in patients with inflammatory bowel disease [IBD] remains controversial. Methods We performed a retrospective observational study of consecutive patients with IBD and PSC, treated with vedolizumab for at least 30 weeks in 22 centres of GETAID from January 2015 to June 2016. The outcomes included a decrease in the serum alkaline phosphatase [ALP] concentration of at least 50% from baseline to Week 30 or 54, a change in any serum liver enzymes concentrations, and an assessment of the efficacy and safety of vedolizumab in IBD. Results Among 75 patients with active IBD and PSC treated with vedolizumab, 21 patients discontinued vedolizumab before Week 30 [due to lack of efficacy in 19 and malignancy in two patients]. In the remaining 54 patients, a decrease in the serum ALP concentration of at least 50% from baseline to Weeks 30 and 54 was observed in four [7%] and four [11%] patients, respectively. No significant change was observed in serum liver enzyme concentrations at week 30 or 54. After a median follow-up period of 19.4 [14.0–29.9] months, nine cases of digestive neoplasia [colorectal neoplasia in seven and cholangiocarcinoma in two] were reported. Conclusions In patients with IBD and PSC, vedolizumab did not improve serum liver enzyme concentrations at week 30 or 54. Nine cases of digestive cancer occurred during the follow-up period, confirming the need for a tight surveillance programme in this population.

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