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Eric Rahrmann and colleagues performed a transposon-based somatic mutagenesis screen for genes involved in malignant peripheral nerve sheath tumors (MPNSTs). They identified many recurrent transposon insertions and nominate Foxr2 as a new oncogene in MPNSTs. Malignant peripheral nerve sheath tumors (MPNSTs) are sarcomas of Schwann cell lineage origin that occur sporadically or in association with the inherited syndrome neurofibromatosis type 1. To identify genetic drivers of MPNST development, we used the Sleeping Beauty ( SB ) transposon-based somatic mutagenesis system in mice with somatic loss of transformation-related protein p53 ( Trp53 ) function and/or overexpression of human epidermal growth factor receptor ( EGFR ). Common insertion site (CIS) analysis of 269 neurofibromas and 106 MPNSTs identified 695 and 87 sites with a statistically significant number of recurrent transposon insertions, respectively. Comparison to human data sets identified new and known driver genes for MPNST formation at these sites. Pairwise co-occurrence analysis of CIS-associated genes identified many cooperating mutations that are enriched in Wnt/β-catenin, PI3K-AKT-mTOR and growth factor receptor signaling pathways. Lastly, we identified several new proto-oncogenes, including Foxr2 (encoding forkhead box R2), which we functionally validated as a proto-oncogene involved in MPNST maintenance.

Eosinophilic gastrointestinal disorders (EGID) are characterized pathologically by excess eosinophils in mucosal biopsies of one or multiple sites in the gastrointestinal (GI) tract, simultaneously or sequentially. Eosinophilic esophagitis (EoE) is the best characterized EGID, and in most patients it is an abnormal immune-mediated response to food antigens. Current recommendations for diagnosis include signs and symptoms of esophageal dysfunction that do not respond to proton-pump inhibitor therapy, and esophageal biopsies that exhibit at least 15 intraepithelial eosinophils in at least one high power field (HPF). Therapy consists of swallowed glucocorticoids or dietary elimination. Eosinophilic gastritis (EG) is the second most common form of EGID, but like all forms of EGID except EoE consensus recommendations for either clinical or pathological diagnosis do not exist. EG may be associated clinically with peripheral blood eosinophilia, hypoalbuminemia, and anemia, and pathologically with marked expansion of lamina propria by dense eosinophilic infiltrates. Eosinophilic enteritis (EE) may be subdivided into eosinophilic duodenitis, eosinophilic jejunitis, and eosinophilic ileitis. Most investigators believe that EE rarely, if ever, exists as a solitary form of EGID and is encountered only in patients who have at least one other affected portion of the GI tract. Eosinophilic colitis (EC) is perhaps the most enigmatic EGID. Distinction of EC from inflammatory bowel disease may be problematic especially in children. Multiple possible etiologies for EGID include hypereosinophilic syndrome, drug reactions, etc. Currently, the only etiology that can be identified histologically is parasitic infestation, if a portion of an invasive parasite is found in mucosal biopsies. This review will provide guidelines for the pathologic diagnosis of the various forms of EGID.

Background: Relapse after corticosteroid withdrawal in eosinophilic esophagitis is not well understood. Objectives: Budesonide oral suspension (BOS) 2.0 mg twice daily (b.i.d.) was evaluated in two consecutive phase III studies (12 and 36 weeks, respectively). For clinicopathologic responders after 12 weeks of BOS treatment, we assessed randomized treatment withdrawal for up to 36 weeks of therapy. Design: Post hoc analysis of a phase III, double-blind, randomized withdrawal study. Methods: Clinicopathologic responders (⩽6 eosinophils per high-power field (eos/hpf) and ⩾30% reduction in Dysphagia Symptom Questionnaire (DSQ) score from baseline) after 12 weeks of BOS were randomized to continue BOS 2.0 mg b.i.d. (BOS–BOS) or withdraw to placebo (PBO; BOS–PBO) for up to 36 weeks. Relapsers (⩾15 eos/hpf (⩾2 esophageal regions) and ⩾4 days of dysphagia (DSQ)) could reinitiate BOS 2.0 mg b.i.d. This post hoc analysis assessed a more clinically relevant relapse definition (⩾15 eos/hpf (⩾1 esophageal region) and ⩾4 days of dysphagia (DSQ)) for BOS–BOS versus BOS–PBO patients over 36 weeks. To account for BOS–PBO patients who reinitiated BOS before week 36, patients’ last observations before reinitiating BOS were carried forward (last observation carried forward (LOCF)) for histologic, symptom, and endoscopic efficacy endpoints (at weeks 12 and 36). Results: Of 48 patients included (BOS–BOS, n = 25; BOS–PBO, n = 23), significantly more BOS–PBO than BOS–BOS patients relapsed over 36 weeks using this post hoc relapse definition (60.9% vs 28.0%; p = 0.022). More BOS–BOS than BOS–PBO patients maintained histologic responses (all thresholds) and showed improvements in symptom and endoscopic efficacy endpoints. Conclusion: More BOS–PBO than BOS–BOS patients relapsed, determined by a more clinically relevant post hoc relapse definition. Using LOCF, more BOS–BOS than BOS–PBO patients also maintained or had improvements in efficacy endpoints. Trial registration: ClinicalTrials.gov identifiers (https://clinicaltrials.gov/): NCT02605837, NCT02736409. Graphical abstract

Dupilumab, a fully human monoclonal antibody, blocks interleukin-4 and interleukin-13 signaling, which have key roles in eosinophilic esophagitis. We conducted a three-part, phase 3 trial in which patients 12 years of age or older underwent randomization in a 1:1 ratio to receive subcutaneous dupilumab at a weekly dose of 300 mg or placebo (Part A) or in a 1:1:1 ratio to receive 300 mg of dupilumab either weekly or every 2 weeks or weekly placebo (Part B) up to week 24. Eligible patients who completed Part A or Part B continued the trial in Part C, in which those who completed Part A received dupilumab at a weekly dose of 300 mg up to week 52 (the Part A-C group); Part C that included the eligible patients from Part B is ongoing. The two primary end points at week 24 were histologic remission (≤6 eosinophils per high-power field) and the change from baseline in the Dysphagia Symptom Questionnaire (DSQ) score (range, 0 to 84, with higher values indicating more frequent or more severe dysphagia). In Part A, histologic remission occurred in 25 of 42 patients (60%) who received weekly dupilumab and in 2 of 39 patients (5%) who received placebo (difference, 55 percentage points; 95% confidence interval [CI], 40 to 71; P<0.001). In Part B, histologic remission occurred in 47 of 80 patients (59%) with weekly dupilumab, in 49 of 81 patients (60%) with dupilumab every 2 weeks, and in 5 of 79 patients (6%) with placebo (difference between weekly dupilumab and placebo, 54 percentage points; 95% CI, 41 to 66 [P<0.001]; difference between dupilumab every 2 weeks and placebo, 56 percentage points; 95% CI, 43 to 69 [not significant per hierarchical testing]). The mean (±SD) DSQ scores at baseline were 33.6±12.41 in Part A and 36.7±11.22 in Part B; the scores improved with weekly dupilumab as compared with placebo, with differences of -12.32 (95% CI, -19.11 to -5.54) in Part A and -9.92 (95% CI, -14.81 to -5.02) in Part B (both P<0.001) but not with dupilumab every 2 weeks (difference in Part B, -0.51; 95% CI, -5.42 to 4.41). Serious adverse events occurred in 9 patients during the Part A or B treatment period (in 7 who received weekly dupilumab, 1 who received dupilumab every 2 weeks, and 1 who received placebo) and in 1 patient in the Part A-C group during the Part C treatment period who received placebo in Part A and weekly dupilumab in Part C. Among patients with eosinophilic esophagitis, subcutaneous dupilumab administered weekly improved histologic outcomes and alleviated symptoms of the disease. (Funded by Sanofi and Regeneron Pharmaceuticals; ClinicalTrials.gov number, NCT03633617.).

Eosinophilic esophagitis (EoE) is a chronic allergic inflammatory condition of the esophagus associated with elevated esophageal eosinophils. Second only to gastroesophageal reflux disease, EoE is one of the leading causes of chronic refractory dysphagia in adults and children. EoE is a clinicopathologic disorder and the histological portion of the diagnosis requires enumerating the density of esophageal eosinophils in esophageal biopsies, and evaluating additional features such as basal zone hyperplasia is helpful. However, this task requires time-consuming, somewhat subjective manual analysis, thus reducing the ability to process the complex tissue structure and infer its relationship with the patient's clinical status. Previous artificial intelligence (AI) approaches that aimed to improve histology-based diagnosis focused on recapitulating identification and quantification of the area of maximal eosinophil density, the gold standard manual metric for determining EoE disease activity. However, this metric does not account for the distribution of eosinophils or other histological features, over the whole slide image. Here, we developed an artificial intelligence platform that infers local and spatial biomarkers based on semantic segmentation of intact eosinophils and basal zone distributions. Besides the maximal density of eosinophils [referred to as Peak Eosinophil Count (PEC)] and a maximal basal zone fraction, we identify the value of two additional metrics that reflect the distribution of eosinophils and basal zone fractions. This approach enables a decision support system that predicts EoE activity and potentially classifies the histological severity of EoE patients. We utilized a cohort that includes 1,066 biopsy slides from 400 subjects to validate the system's performance and achieved a histological severity classification accuracy of 86.70%, sensitivity of 84.50%, and specificity of 90.09%. Our approach highlights the importance of systematically analyzing the distribution of biopsy features over the entire slide and paves the way toward a personalized decision support system that will assist not only in counting cells but can also potentially improve diagnosis and provide treatment prediction.

Dupilumab, a human monoclonal antibody that blocks interleukin-4 and interleukin-13 pathways, led to histologic remission in a significantly higher percentage of children with eosinophilic esophagitis than placebo.

In a randomized, placebo-controlled trial involving patients 12 to 65 years of age with eosinophilic esophagitis, benralizumab reduced esophageal eosinophil counts but did not reduce dysphagia symptoms.

There are a lack of data on the quantity and location of eosinophils in the gastrointestinal tract of healthy individuals. Accordingly, we examined gastrointestinal biopsies obtained during endoscopic evaluation of pediatric patients. Biopsies were previously interpreted as having no diagnostic abnormality. The presence of extracellular eosinophil constituents and the quantity of eosinophils in atopic versus nonatopic individuals was determined. In the esophagus, eosinophils were present in only 2.7% of high-power fields (hpf), with a mean value of 0.03 ± 0.10 eosinophils/hpf (mean ± standard deviation) and a maximum of 1 eosinophil/hpf. Examination of the antrum and fundus revealed similar numbers of eosinophils in the lamina propria (1.9 ± 1.3 and 2.1 ± 2.4 eosinophils/hpf, respectively), with no eosinophils observed in the surface epithelium. In the small intestine, there were 9.6 ± 5.3 (maximum, 26 eosinophils/hpf) and 12.4 ± 5.4 eosinophils/hpf (maximum, 28 eosinophils/hpf) in the intercryptal lamina propria of the duodenum and ileum, respectively. The number of eosinophils in the surface epithelium and crypt epithelium was minimal. In the large intestine, the highest concentration of eosinophils was observed in the cecum (20.3 ±8.2 eosinophils/hpf; maximum, 50 eosinophils/hpf), and there were lower concentrations in the transverse and sigmoid colon (16.3 ± 5.6 and 8.3 ± 5.9 eosinophils/hpf, respectively). The percentage of fields demonstrating extracellular eosinophil granules in all gastrointestinal segments was 70% to 93%, and extracellular granules were most numerous at the edge of the biopsy (P < 0.05). Atopic and nonatopic patients had comparable numbers of eosinophils. These data establish baseline gastrointestinal eosinophil values in pediatric patients without apparent pathological disease.

Anorectal malformations are congenital anomalies that form a spectrum from the most benign type with excellent functional prognosis, to very complex, such as cloaca in females in which the rectum, vagina and urethra fail to develop separately and instead drain via a single common channel into the perineum. The severity of this phenotype suggests that the defect occurs early during embryonic development of the organs derived from the cloaca. Due to the inability to directly investigate human cloaca development, current research has relied on the use of mouse models of anorectal malformations. However, even studies of mouse embryos lack analysis of the earliest stages of cloaca patterning and morphogenesis. Here we compared human and mouse cloaca development and retrospectively identified that early mis-patterning of the embryonic cloaca may underlie the most severe forms of anorectal malformation in humans. In mouse, we identified that defective Shh signaling results in early dorsal-ventral epithelial abnormalities prior to the reported defects in septation. This is manifested by the absence of Sox2 and aberrant expression of Keratins in the cloaca of Shh knockout mice. Shh knockout embryos additionally develop a hypervascular stroma, which is defective in BMP signaling. These epithelial and stromal defects persist later creating an indeterminate epithelium with molecular alterations in the common channel. We then used these animals to perform a broad comparison with patients with mild to severe forms of anorectal malformations including cloaca. We found striking parallels with the Shh mouse model including nearly identical defective molecular identity of the epithelium and surrounding stroma. Our work strongly suggests that early cloacal epithelial differentiation defects may be the underlying cause of severe forms of anorectal malformations in humans. Moreover, deranged hedgehog and BMP signaling is correlated with severe anorectal malformations in both mouse and humans.