Multicenter, Observational Study of Lanreotide Autogel for the Treatment of Patients with Neuroendocrine Tumors in Routine Clinical Practice in Germany and Austria.

BACKGROUND: The long-acting somatostatin analog lanreotide autogel is effective in the treatment of patients with neuroendocrine tumors. OBJECTIVE: To evaluate the long-term treatment response in patients with neuroendocrine tumors receiving lanreotide autogel in routine clinical practice. METHODS: Non-interventional, 24-month study in patients with neuroendocrine tumors treated with lanreotide autogel (NCT01840449). RESULTS: Patients (n=80) from 26 centers in Germany and Austria were enrolled. Neuroendocrine tumors were mainly grade 1/2, metastasized, intestinal, and associated with carcinoid syndrome; 88.9% had received previous neuroendocrine tumor treatment. Of those, 84.4% had previous surgery, 18.7% had received octreotide. The primary endpoint, defined by a <50% chromogranin A increase at month 12 compared with the lowest value between baseline and month 3 was achieved by 89.5% patients. Stable disease according to Response Evaluation Criteria in Solid Tumors 1.1 was observed in 76.9 and 75.0% patients at months 12 and 24 of lanreotide treatment, respectively. Mean change of chromogranin A levels from baseline to month 24 was -0.12 × upper limit of normal (95% CI, -0.22; -0.45). In a post hoc analysis, 38.5% of the subgroup of patients with carcinoid syndrome had daily diarrhea at baseline vs. 21.4% at month 24. At baseline, 27.8% of patients received lanreotide 120 mg every 4 weeks vs. 56.7% at month 24. Quality of life data were heterogeneous. No new safety issues arose and/or required further investigation. CONCLUSIONS: Our study reflects routine lanreotide autogel use in patients with advanced/metastatic neuroendocrine tumors. This analysis shows effectiveness with stabilization of disease-related symptoms and good tolerability of lanreotide autogel in clinical practice.

Professional Assessment of the Impact of COVID-19 on Handling NET Patients.

The treatment and monitoring of patients with neuroendocrine tumors (NET) has been a major challenge during the COVID-19 pandemic. In a survey, we investigated the influence of COVID-19 on the care of NET patients in the German speaking countries Germany, Austria and Switzerland. The multidisciplinarity of all treating physicians in the outpatient and inpatient sector was reflected in our survey. Furthermore, we were able to present findings pertaining to the university and non-university medical care. Overall, only a minority of appointments were cancelled, mostly as a result of medical prioritization and less for fear of infection by patients. In the university sector, longer delays for diagnostic measures were observed in comparison to non-university care. During the COVID-19 crisis, NET patients rarely changed their current therapy, but the pandemic impacted the assessment of the different treatment modalities at risk of developing severe COVID-19 disease. This survey provides the first real-world data on the treatment of NET patients from the physicians' perspective during the COVID-19 crisis. Despite delays in diagnostic procedures and outpatient appointments, only a minority of physicians foresee a major impact of COVID-19 on NET patient care.

Correction to: Dsg2 via Src-mediated transactivation shapes EGFR signaling towards cell adhesion.

In the published article, the legend for figure 3 was incorrect. The correct legend is given below.

Neurotrophic factor GDNF regulates intestinal barrier function in inflammatory bowel disease.

Impaired intestinal epithelial barrier (IEB) function with loss of desmosomal junctional protein desmoglein 2 (DSG2) is a hallmark in the pathogenesis of inflammatory bowel disease (IBD). While previous studies have reported that glial cell line-derived neurotrophic factor (GDNF) promotes IEB function, the mechanisms are poorly understood. We hypothesized that GDNF is involved in the loss of DSG2, resulting in impaired IEB function as seen in IBD. In the inflamed intestine of patients with IBD, there was a decrease in GDNF concentrations accompanied by a loss of DSG2, changes of the intermediate filament system, and increased phosphorylation of p38 MAPK and cytokeratins. DSG2-deficient and RET-deficient Caco2 cells revealed that GDNF specifically recruits DSG2 to the cell borders, resulting in increased DSG2-mediated intercellular adhesion via the RET receptor. Challenge of Caco2 cells and enteroids with proinflammatory cytokines as well as dextran sulfate sodium-induced (DSS-induced) colitis in C57Bl/6 mice led to impaired IEB function with reduced DSG2 mediated by p38 MAPK-dependent phosphorylation of cytokeratins. GDNF blocked all inflammation-induced changes in the IEB. GDNF attenuates inflammation-induced impairment of IEB function caused by the loss of DSG2 through p38 MAPK-dependent phosphorylation of cytokeratin. The reduced GDNF in patients with IBD indicates a disease-relevant contribution to the development of IEB dysfunction.

Mechanical loading of desmosomes depends on the magnitude and orientation of external stress.

Desmosomes are intercellular adhesion complexes that connect the intermediate filament cytoskeletons of neighboring cells, and are essential for the mechanical integrity of mammalian tissues. Mutations in desmosomal proteins cause severe human pathologies including epithelial blistering and heart muscle dysfunction. However, direct evidence for their load-bearing nature is lacking. Here we develop Förster resonance energy transfer (FRET)-based tension sensors to measure the forces experienced by desmoplakin, an obligate desmosomal protein that links the desmosomal plaque to intermediate filaments. Our experiments reveal that desmoplakin does not experience significant tension under most conditions, but instead becomes mechanically loaded when cells are exposed to external mechanical stresses. Stress-induced loading of desmoplakin is transient and sensitive to the magnitude and orientation of the applied tissue deformation, consistent with a stress absorbing function for desmosomes that is distinct from previously analyzed cell adhesion complexes.

Desmoglein 2, but not desmocollin 2, protects intestinal epithelia from injury.

Desmosomes are the least understood intercellular junctions in the intestinal epithelia and provide cell-cell adhesion via the cadherins desmoglein (Dsg)2 and desmocollin (Dsc)2. We studied these cadherins in Crohn's disease (CD) patients and in newly generated conditional villin-Cre DSG2 and DSC2 knockout mice (DSG2ΔIEC; DSC2ΔIEC). CD patients exhibited altered desmosomes and reduced Dsg2/Dsc2 levels. The intestines of both transgenic animal lines were histopathologically inconspicuous. However, DSG2ΔIEC, but not DSC2ΔIEC mice displayed an increased intestinal permeability, a wider desmosomal space as well as alterations in desmosomal and tight junction components. After dextran sodium sulfate (DSS) treatment and Citrobacter rodentium exposure, DSG2ΔIEC mice developed a more-pronounced colitis, an enhanced intestinal epithelial barrier disruption, leading to a stronger inflammation and activation of epithelial pSTAT3 signaling. No susceptibility to DSS-induced intestinal injury was noted in DSC2ΔIEC animals. Dsg2 interacted with the cytoprotective chaperone Hsp70. Accordingly, DSG2ΔIEC mice had lower Hsp70 levels in the plasma membrane compartment, whereas DSC2ΔIEC mice displayed a compensatory recruitment of galectin 3, a junction-tightening protein. Our results demonstrate that Dsg2, but not Dsc2 is required for the integrity of the intestinal epithelial barrier in vivo.

Dsg2 via Src-mediated transactivation shapes EGFR signaling towards cell adhesion.

Rapidly renewing epithelial tissues such as the intestinal epithelium require precise tuning of intercellular adhesion and proliferation to preserve barrier integrity. Here, we provide evidence that desmoglein 2 (Dsg2), an adhesion molecule of desmosomes, controls cell adhesion and proliferation via epidermal growth factor receptor (EGFR) signaling. Dsg2 is required for EGFR localization at intercellular junctions as well as for Src-mediated EGFR activation. Src binds to EGFR and is required for localization of EGFR and Dsg2 to cell-cell contacts. EGFR is critical for cell adhesion and barrier recovery. In line with this, Dsg2-deficient enterocytes display impaired barrier properties and increased cell proliferation. Mechanistically, Dsg2 directly interacts with EGFR and undergoes heterotypic-binding events on the surface of living enterocytes via its extracellular domain as revealed by atomic force microscopy. Thus, our study reveals a new mechanism by which Dsg2 via Src shapes EGFR function towards cell adhesion.

Desmoglein 2 regulates the intestinal epithelial barrier via p38 mitogen-activated protein kinase.

Intestinal epithelial barrier properties are maintained by a junctional complex consisting of tight junctions (TJ), adherens junctions (AJ) and desmosomes. Desmoglein 2 (Dsg2), an adhesion molecule of desmosomes and the only Dsg isoform expressed in enterocytes, is required for epithelial barrier properties and may contribute to barrier defects in Crohn's disease. Here, we identified extradesmosomal Dsg2 on the surface of polarized enterocytes by Triton extraction, confocal microscopy, SIM and STED. Atomic force microscopy (AFM) revealed Dsg2-specific binding events along the cell border on the surface of enterocytes with a mean unbinding force of around 30pN. Binding events were blocked by an inhibitory antibody targeting Dsg2 which under same conditions activated p38MAPK but did not reduce cell cohesion. In enterocytes deficient for Dsg2, p38MAPK activity was reduced and both barrier integrity and reformation were impaired. Dsc2 rescue did not restore p38MAPK activity indicating that Dsg2 is required. Accordingly, direct activation of p38MAPK in Dsg2-deficient cells enhanced barrier reformation demonstrating that Dsg2-mediated activation of p38MAPK is crucial for barrier function. Collectively, our data show that Dsg2, beside its adhesion function, regulates intestinal barrier function via p38MAPK signalling. This is in contrast to keratinocytes and points towards tissue-specific signalling functions of desmosomal cadherins.