Targeting myeloid suppressive cells revives cytotoxic anti-tumor responses in pancreatic cancer.

Immunotherapy for cancer that aims to promote T cell anti-tumor activity has changed current clinical practice, where some previously lethal cancers have now become treatable. However, clinical trials with low response rates have been disappointing for pancreatic ductal adenocarcinoma (PDAC). One suggested explanation is the accumulation of dominantly immunosuppressive tumor-associated macrophages and myeloid-derived suppressor cells in the tumor microenvironment (TME). Using retrospectively collected tumor specimens and transcriptomic data from PDAC, we demonstrate that expression of the scavenger receptor MARCO correlates with poor prognosis and a lymphocyte-excluding tumor phenotype. PDAC cell lines produce IL-10 and induce high expression of MARCO in myeloid cells, and this was further enhanced during hypoxic conditions. These myeloid cells suppressed effector T and natural killer (NK) cells and blocked NK cell tumor infiltration and tumor killing in a PDAC 3D-spheroid model. Anti-human MARCO (anti-hMARCO) antibody targeting triggered the repolarization of tumor-associated macrophages and activated the inflammasome machinery, resulting in IL-18 production. This in turn enhanced T cell and NK cell functions. The targeting of MARCO thus remodels the TME and represents a rational approach to make immunotherapy more efficient in PDAC patients.

Molecular analysis of cyst fluids improves the diagnostic accuracy of pre-operative assessment of pancreatic cystic lesions.

Pancreatic cystic lesions (PCL) are increasingly diagnosed. Endoscopic ultrasound fine-needle aspiration (EUS-FNA) cytology is often used for diagnostic confirmation but can be inconclusive. In this study, the role of molecular analyses in the pre-operative diagnostics of PCL is evaluated. Targeted Next Generation Sequencing (NGS) applied on cytology smears was retrospectively evaluated in a cohort of 37 resected PCL. Usefulness of NGS on fresh cyst fluids was tested in a prospective cohort of patients with newly diagnosed PCL (n = 71). In the retrospective cohort, cytology plus NGS displayed higher sensitivity (94.1% vs. 87.1%) and specificity (100% vs. 50%) than cytology alone for the detection of mucinous neoplasms. In the prospective cohort, sensitivity and specificity of conventional cytology alone were 54.2% and 100% for the detection of mucinous neoplasia and 50.0% and 100% for the detection of high-grade dysplasia, respectively. Adding NGS, all lesions which underwent histopathologic verification (12/71, 17%) could be classified without false positive or false negative results regarding the detection of mucinous neoplasm so far. NGS analysis of cfDNA in PCL fluids is feasible and can increase diagnostic accuracy in the detection of mucinous neoplasms compared to cytology alone. However, algorithms for the detection of high-risk lesions need further improvement.

ADAM8 affects glioblastoma progression by regulating osteopontin-mediated angiogenesis.

Glioblastoma multiforme (GBM) is the most aggressive type of brain cancer with a median survival of only 15 months. To complement standard treatments including surgery, radiation and chemotherapy, it is essential to understand the contribution of the GBM tumor microenvironment. Brain macrophages and microglia particularly contribute to tumor angiogenesis, a major hallmark of GBM. ADAM8, a metalloprotease-disintegrin strongly expressed in tumor cells and associated immune cells of GBMs, is related to angiogenesis and correlates with poor clinical prognosis. However, the specific contribution of ADAM8 to GBM tumorigenesis remains elusive. Knockdown of ADAM8 in U87 glioma cells led to significantly decreased angiogenesis and tumor volumes of these cells after stereotactic injection into striate body of mice. We found that the angiogenic potential of ADAM8 in GBM cells and in primary macrophages is mediated by the regulation of osteopontin (OPN), an important inducer of tumor angiogenesis. By in vitro cell signaling analyses, we demonstrate that ADAM8 regulates OPN via JAK/STAT3 pathway in U87 cells and in primary macrophages. As ADAM8 is a dispensable protease for physiological homeostasis, we conclude that ADAM8 could be a tractable target to modulate angiogenesis in GBM with minor side-effects.

Bile-Based Cell-Free DNA Analysis Is a Reliable Diagnostic Tool in Pancreatobiliary Cancer.

Currently available serum biomarkers for pancreatobiliary cancers lack sensitivity and specificity and ultimate diagnosis still requires invasive procedures for histological confirmation. The detection of tumor-specific genetic aberrations with utilization of cell free DNA (cfDNA) is a less invasive approach than traditional tissue biopsies; however, it has not been implemented into clinical routine. In this study, we investigated bile as a liquid biopsy source in pancreatobiliary cancers and compared its potential as cell-free DNA source to plasma. Blood (n = 37) and bile (n = 21) samples were collected from patients affected by pancreatic ductal adenocarcinoma (PDAC) and extrahepatic cholangiocarcinoma (CCA) or with non-malignant biliary obstructions (blood n = 16; bile n = 21). Panel-based next generation sequencing (NGS) and digital droplet PCR (ddPCR) were applied for tumor mutation profiling. NGS results from matched tumor tissues (n = 29) served as comparison. Sequencing of cfDNA from bile resulted in detection of 96.2% of the pathogenic tumor mutations found in matched tissue samples. On the other hand, only 31.6% of pathogenic tumor mutations found in tissue could be detected in plasma. In a direct comparison, only half of the mutations detected in bile cfDNA were concordantly detected in plasma from the same patients. Panel NGS and ddPCR displayed comparable sensitivity. In conclusion, bile is a suitable source of cfDNA for the diagnosis of pancreatobiliary cancer and performs more reliably than plasma. Although primary diagnosis still requires histologic confirmation, bile-derived cfDNA could offer an alternative if tissue sampling is not feasible and might allow less invasive disease monitoring.