Worldwide, gastrointestinal (GI) cancers account for a significant amount of cancer-related mortality. Tests that allow an early diagnosis could lead to an improvement in patient survival. Liquid biopsies (LBs) due to their non-invasive nature as well as low risk are the current focus of cancer research and could be a promising tool for early cancer detection. LB involves the sampling of any biological fluid (e.g., blood, urine, saliva) to enrich and analyze the tumor’s biological material. LBs can detect tumor-associated components such as circulating tumor DNA (ctDNA), extracellular vesicles (EVs), and circulating tumor cells (CTCs). These components can reflect the status of the disease and can facilitate clinical decisions. LBs offer a unique and new way to assess cancers at all stages of treatment, from cancer screenings to prognosis to management of multidisciplinary therapies. In this review, we will provide insights into the current status of the various types of LBs enabling early detection and monitoring of GI cancers and their use in in vitro diagnostics.

Immunotherapy has become increasingly important in the treatment of colorectal cancer (CRC). Currently, CD73, also known as ecto-5′-nucleotidase (NT5E), has gained considerable interest as a potential therapeutic target. CD73 is one of the key enzymes catalyzing the conversion of extracellular ATP into adenosine, which in turn exerts potent immune suppressive effects. However, the role of CD73 expression on various cell types within the CRC tumor microenvironment remains unresolved. The expression of CD73 on various cell types has been described recently, but the role of CD73 on B-cells in CRC remains unclear. Therefore, we analyzed CD73 on B-cells, especially on tumor-infiltrating B-cells, in paired tumor and adjacent normal tissue samples from 62 eligible CRC patients. The highest expression of CD73 on tumor-infiltrating B-cells was identified on class-switched memory B-cells, followed by naive B-cells, whereas no CD73 expression was observed on plasmablasts. Clinicopathological correlation analysis revealed that higher CD73⁺ B-cells infiltration in the CRC tumors was associated with better overall survival. Moreover, metastasized patients showed a significantly decreased number of tumor-infiltrating CD73⁺ B-cells. Finally, neoadjuvant therapy correlated with reduced CD73⁺ B-cell numbers and CD73 expression on B-cells in the CRC tumors. As promising new immune therapies are being developed, the role of CD73⁺ B-cells and their subsets in the development of colorectal cancer should be further explored to find new therapeutic options.

Pancreatic ductal adenocarcinoma (PDAC) ranks among the most fatal cancer diseases, widely accepted to have the most dismal prognoses. Although immunotherapy has broadly revolutionized cancer treatment, its value in PDAC appears to be relatively low. Exhibiting protumoral effects, monocytes have recently been proposed as potential targets of such immunotherapeutic regimens. However, to date, the body of evidence on monocytes’ role in PDAC is scarce. Therefore, we analyzed monocytes in the peripheral blood of 58 PDAC patients prior to surgery and compared them to healthy individuals. PDAC patients showed increased levels of monocytes when compared to healthy controls In addition, patients with perineural infiltration demonstrated a higher percentage of monocytes compared to non-infiltrating tumors and PDAC G3 was associated with higher monocyte levels than PDAC G2. Patients with monocyte levels > 5% were found to have an 8.9-fold increased risk for a G3 and perineural infiltrated PDAC resulting in poorer survival compared to patients with <5% monocyte levels. Furthermore, PDAC patients showed increased expressions of CD86 and CD11c and decreased expressions of PD-L1 on monocytes compared to healthy individuals. Finally, levels of monocytes correlated positively with concentrations of IL-6 and TNF-α in plasma of PDAC patients. Based on our findings, we propose monocytes as a novel prognostic biomarker. Large-scale studies are needed to further decipher the role of monocytes in PDAC and investigate their potential as therapeutic targets.

Background: Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest forms of cancer and peritoneal dissemination is one major cause for this poor prognosis. Exosomes have emerged as promising biomarkers for gastrointestinal cancers and can be found in all kinds of bodily fluids, also in peritoneal fluid (PF). This is a unique sample due to its closeness to gastrointestinal malignancies. The receptor tyrosine kinase-like orphan receptor 1 (ROR1) has been identified as a potential biomarker in human cancers and represents a promising target for an immunotherapy approach, which could be considered for future treatment strategies. Here we prospectively analyzed the exosomal surface protein ROR1 (exo-ROR1) in PF in localized PDAC patients (PER-) on the one hand and peritoneal disseminated tumor stages (PER+) on the other hand followed by the correlation of exo-ROR1 with clinical-pathological parameters.Methods: Exosomes were isolated from PF and plasma samples of non-cancerous (NC) (n = 15), chronic pancreatitis (CP) (n = 4), localized PDAC (PER-) (n = 18) and peritoneal disseminated PDAC (PER+) (n = 9) patients and the surface protein ROR1 was detected via FACS analysis. Additionally, soluble ROR1 in PF was analyzed. ROR1 expression in tissue was investigated using western blots (WB), qPCR, and immunohistochemistry (IHC). Exosome isolation was proven by Nano Tracking Analysis (NTA), WB, Transmission electron microscopy (TEM), and BCA protein assay. The results were correlated with clinical data and survival analysis was performed.Results: PDAC (PER+) patients have the highest exo-ROR1 values in PF and can be discriminated from NC (p <0.0001), PDAC (PER-) (p <0.0001), and CP (p = 0.0112). PDAC (PER-) can be discriminated from NC (p = 0.0003). In plasma, exo-ROR1 is not able to distinguish between the groups. While there is no expression of ROR1 in the exocrine pancreatic tissue, PDAC and peritoneal metastasis show expression of ROR1. High exo-ROR1 expression in PF is associated with lower overall survival (p = 0.0482).Conclusion: With exo-ROR1 in PF we found a promising diagnostic and prognostic biomarker possibly discriminating between NC, PDAC (PER-) and PDAC (PER+) and might shed light on future diagnostic and therapeutic concepts in PDAC.

Background: Anastomotic leakage (AL) and stenosis (AS) are two of the most severe postoperative complications after total gastrectomy with esophagojejunostomy. The stapler diameter can be chosen by the surgeon. Therefore, this study aims to assess the correlation between the stapler size as main independent variable as well as other different risk factors and AL and AS. Methods: We conducted a retrospective analysis of data from 356 patients who underwent open total gastrectomy between 2000 and 2018, mostly due to gastric cancer (96.9%). After propensity score matching the outcome parameters AL and AS were compared between the two stapler size groups. We also assessed different risk factors for AL and AS in cancer patients using multivariate analysis. Results: Small circular stapler diameter (21/25 mm; n = 147 vs 28/29/31 mm; n = 209) was identified as a significant risk factor for the occurrence of AL (10% vs 4% for smaller vs larger staplers; P = 0.042). In multivariate analysis for the occurrence of AL an ASA score ≥ 3 could be identified as a risk factor (OR 2.85; 95% CI = 1.13–7.15; P = 0.026). Additionally, smaller stapler size could be identified as a risk factor for AS (OR small 1.00, OR large 0.24; 95% CI: 0.06–0.97; P = 0.045). AL was associated with lower survival (18.1 vs 38.16 months; P = 0.0119). Conclusion: The application of a larger circular stapler for esophagojejunostomy in open total gastrectomy shows significantly lower rates of AL and stenosis. Therefore, the largest possible stapler diameter should be applied.

The poor prognosis of pancreatic ductal adenocarcinoma (PDAC) is largely due to several challenges, such as late diagnosis, early metastasis, limited response to chemotherapy, aggressive tumor biology, and high rates of tumor recurrence. Therefore, the development of a non-invasive and effective method for early detection of PDAC is crucial to improving patient outcomes. Continued research and exploration in this area are essential to enhance early detection methods and ultimately improve the prognosis for individuals with PDAC. In this study, we examined 37 exosomal surface proteins through a multiplex flow cytometry test on peripheral plasma samples from a group of 51 clinical control individuals (including healthy volunteers and non-cancer patients (Cholecystectomy, Hernia, healthy volunteers)), 21 pancreatitis, and 48 patients diagnosed with PDAC. Our research findings revealed that the level of exosomal CD40 expression is significantly lower in patients with PDAC and pancreatitis compared to non-cancer patients (p < 0.0001). Additionally, pancreatitis patients exhibited higher levels of exosomal CD25 expression than PDAC patients (p = 0.0104). PDAC patients with higher exo-CD40 had worse survival than patients with lower exo-CD40 (p = 0.0035). Similarly, PDAC patients with higher exo-CD25 showed worse survival in comparison to patients with lower exo-CD25 (p = 0.04). Statistical analysis revealed that exosomal CD40 achieved an AUC of 0.827 in distinguishing PDAC from clinical controls. Combining exo-CD40 along with exo-CD25 and CA19-9 discriminated PDAC patients from clinical controls with an AUC of 0.92. Exo-CD40 and exo-CD25 proteins found in exosomes isolated from plasma can serve as excellent non-invasive biomarkers for the early diagnosis of PDAC. Further larger scale studies are needed to validate combined exo-CD40 and exo-CD25 as a diagnostic tool for the identification of PDAC patients through non-invasive liquid biopsy.