Plasma protein biomarkers for the detection of pancreatic neuroendocrine tumors and differentiation from small intestinal neuroendocrine tumors.

There is an unmet need for novel biomarkers to diagnose and monitor patients with neuroendocrine neoplasms. The EXPLAIN study explores a multi-plasma protein and supervised machine learning strategy to improve the diagnosis of pancreatic neuroendocrine tumors (PanNET) and differentiate them from small intestinal neuroendocrine tumors (SI-NET). At time of diagnosis, blood samples were collected and analyzed from 39 patients with PanNET, 135 with SI-NET (World Health Organization Grade 1-2) and 144 controls. Exclusion criteria were other malignant diseases, chronic inflammatory diseases, reduced kidney or liver function. Prosed Oncology-II (i.e., OLink) was used to measure 92 cancer related plasma proteins. Chromogranin A was analyzed separately. Median age in all groups was 65-67 years and with a similar sex distribution (females: PanNET, 51%; SI-NET, 42%; controls, 42%). Tumor grade (G1/G2): PanNET, 39/61%; SI-NET, 46/54%. Patients with liver metastases: PanNET, 78%; SI-NET, 63%. The classification model of PanNET versus controls provided a sensitivity (SEN) of 0.84, specificity (SPE) 0.98, positive predictive value (PPV) of 0.92 and negative predictive value (NPV) of 0.95, and area under the receiver operating characteristic curve (AUROC) of 0.99; the model for the discrimination of PanNET versus SI-NET providing a SEN 0.61, SPE 0.96, PPV 0.83, NPV 0.90 and AUROC 0.98. These results suggest that a multi-plasma protein strategy can significantly improve diagnostic accuracy of PanNET and SI-NET.

A Plasma Protein Biomarker Strategy for Detection of Small Intestinal Neuroendocrine Tumors.

BACKGROUND: Small intestinal neuroendocrine tumors (SI-NETs) are difficult to diagnose in the early stage of disease. Current blood biomarkers such as chromogranin A (CgA) and 5-hydroxyindolacetic acid have low sensitivity (SEN) and specificity (SPE). This is a first preplanned interim analysis (Nordic non-interventional, prospective, exploratory, EXPLAIN study [NCT02630654]). Its objective is to investigate if a plasma protein multi-biomarker strategy can improve diagnostic accuracy (ACC) in SI-NETs. METHODS: At the time of diagnosis, before any disease-specific treatment was initiated, blood was collected from patients with advanced SI-NETs and 92 putative cancer-related plasma proteins from 135 patients were analyzed and compared with the results of age- and sex-matched controls (n = 143), using multiplex proximity extension assay and machine learning techniques. RESULTS: Using a random forest model including 12 top ranked plasma proteins in patients with SI-NETs, the multi-biomarker strategy showed SEN and SPE of 89 and 91%, respectively, with negative predictive value (NPV) and positive predictive value (PPV) of 90 and 91%, respectively, to identify patients with regional or metastatic disease with an area under the receiver operator characteristic curve (AUROC) of 99%. In 30 patients with normal CgA concentrations, the model provided a diagnostic SPE of 98%, SEN of 56%, and NPV 90%, PPV of 90%, and AUROC 97%, regardless of proton pump inhibitor intake. CONCLUSION: This interim analysis demonstrates that a multi-biomarker/machine learning strategy improves diagnostic ACC of patients with SI-NET at the time of diagnosis, especially in patients with normal CgA levels. The results indicate that this multi-biomarker strategy can be useful for early detection of SI-NETs at presentation and conceivably detect recurrence after radical primary resection.

Botulinum toxin treatment of spasticity targeted to muscle endplates: an international, randomised, evaluator-blinded study comparing two different botulinum toxin injection strategies for the treatment of upper limb spasticity.

OBJECTIVES: The therapeutic effects of botulinum neurotoxin (BoNT) are well documented in upper limb spasticity. However, several factors may influence treatment efficacy, including targeting of neuromuscular junctions (NMJs). We examined whether NMJ-targeted BoNT injections were non-inferior, in terms of efficacy, to current injection practices. DESIGN: Open-label prospective evaluator-blinded study. SETTING: Conducted across 20 medical centres in Denmark, Finland, Norway and Sweden (24 September 2012 to 11 March 2015). PARTICIPANTS: Aged ˃18 years with upper limb spasticity (Modified Ashworth Scale [MAS] score of 2 or 3) following stroke or traumatic brain injury, had received ≥2 consecutive BoNT-A treatment cycles (the latest of which was abobotulinumtoxinA [aboBoNT-A]) and needed BoNT-A retreatment (same modality as previous cycle). Patients requiring aboBoNT-A doses >800units were excluded. In total, 88 patients were randomised (intention-to-treat [ITT] population), most were male (n=58/88, 65.9%) and 54/88 (61.4%) completed the study (per protocol [PP] population). INTERVENTIONS: Randomisation (1:1) to receive a single dose of aboBoNT-A (≤800 U) according to either current clinical practice (300 U/mL) or as an NMJ-targeted injection (100 U/mL). PRIMARY OUTCOME MEASURE: Proportion of patients with a ≥1 level reduction from baseline in MAS score at week 4 post-injection (responders). RESULTS: In the ITT population, the proportion of responders at elbow flexors was 72.7% in the current practice group and 56.8% in the NMJ-targeted group (adjusted difference -0.1673 [95% CIs: -0.3630 to 0.0284]; p=0.0986). Similar results were observed in the PP population (69.0% vs 68.0%, respectively, adjusted difference 0.0707 [-0.1948 to 0.3362]; p=0.6052). CONCLUSIONS: Owing to the limited number of participants, non-inferiority of NMJ-targeted injections could not be determined. However, there was no statistical difference between groups. Larger studies are needed confirm whether the two techniques offer comparable efficacy. TRIAL REGISTRATION NUMBER: NCT01682148.

Enhanced ouabain resistance gene as a eukaryotic selection marker.

Current selection markers allow selection by antibiotics or fluorescent/magnetic sorting by green fluorescent protein or membrane antigens. Antibiotic selection proceeds on a time scale of weeks, and flourescence-activated cell sorting requires complex equipment and may generate false-positive results when selection is performed too early after transduction with membrane markers. We have characterized an endogenous eukaryotic selection marker, the ouabain resistance gene (Oua(r)), which has the potential for quick and efficient in vitro selection of target cells. The Oua(r) used by us is derived from the rat alpha(1) isoform of Na(+),K(+)-ATPase, where leucine at position 799 is substituted for cysteine by targeted mutagenesis. This mutation confers resistance to more than 1 mM ouabain in vitro. We show that cells transfected with plasmid or transduced with a retrovirus vector encoding Oua(r) can be selected efficiently with ouabain in 48 hr and that a pure population of cells can be obtained. The ouabain resistance gene may be useful as a selection marker in general molecular biology, preclinical, and clinical applications because of its short selection time and also because of the safety of ouabain for human use.

Changes in Na(+)-K(+)-ATPase activity influence cell attachment to fibronectin.

Most vital cellular functions are dependent on a fine-tuned regulation of intracellular ion homeostasis. Here we have demonstrated, using COS cells that were untransfected or transfected with wild-type rat ouabain-resistant Na(+)-K(+)-ATPase, that partial inhibition of Na(+)-K(+)-ATPase has a dramatic influence on cell attachment to fibronectin. Ouabain dose-dependently decreased attachment in untransfected cells and in cells expressing wild-type Na(+)-K(+)-ATPase, but not in cells expressing ouabain-insensitive Na(+)-K(+)-ATPase, whereas inhibition of Na(+)-K(+)-ATPase by lowering extracellular K(+) concentration decreased attachment in all three cell types. Thirty percent inhibition of Na(+)-K(+)-ATPase significantly attenuated attachment. Na(+)-K(+)-ATPase inhibition caused a sustained increase in the intracellular Ca(2+) concentration that obscured Ca(2+) transients observed in untreated cells during attachment. Inhibitors of Ca(2+) transporters significantly decreased attachment, but inhibition of Na(+)/H(+) exchanger did not. Ouabain reduced focal adhesion kinase autophosphorylation but had no effect on cell surface integrin expression. These results suggest that the level of Na(+)-K(+)-ATPase activity strongly influences cell attachment, possibly by an effect on intracellular Ca(2+).