Epidemiology of pediatric astrovirus gastroenteritis in a Nicaraguan birth cohort.

Background: Astrovirus is a leading cause of acute gastroenteritis in children worldwide. However, few prospective studies have analyzed astrovirus in community-dwelling pediatric populations in low-and-middle-income countries. Methods: We assessed the incidence, risk factors, clinical characteristics, genotypes, viral coinfections and seasonality of astrovirus gastroenteritis in 443 healthy Nicaraguan children born in 2017-2018, followed for 36 months. Children were recruited from maternity hospitals and birth records in an economically-diverse neighborhood of León, the second-largest city in Nicaragua. Astrovirus-positive episodes and genotypes were identified from diarrheal specimens with reverse transcription quantitative polymerase chain reaction and Sanger sequencing. Results: Of 1708 total specimens tested, eighty children (18%) experienced at least 1 astrovirus episode, and 9 experienced repeat episodes, mostly during the rainy season (May-October). The incidence of astrovirus episodes was 7.8/100 child-years (95% CI: 6.2, 9.8). Genotype-specific incidence of astrovirus also exhibited seasonality. Median age of astrovirus episode onset was 16 months (IQR 9, 23). Initial astrovirus episodes were not associated with protection against future episodes during the age span studied. Astrovirus cases were exclusively breastfed for a shorter period than uninfected children, and the human milk oligosaccharide lacto-N-fucopentaose-I was more concentrated in mothers of these children. Home toilets appeared to protect against future astrovirus episodes (HR=0.19, 95% CI 0.04-0.91). Human astrovirus-5 episodes, comprising 15% of all typed episodes, were associated with longer diarrhea and more symptomatic rotavirus co-infections. Conclusion: Astrovirus was a common cause of gastroenteritis in this cohort, and future studies should clarify the role of astrovirus genotype in clinical infection severity.

KDR genetic predictor of toxicities induced by sorafenib and regorafenib.

No biomarkers are available to predict toxicities induced by VEGFR TKIs. This study aimed to identify markers of toxicities induced by these drugs using a discovery-validation approach. The discovery set included 140 sorafenib-treated cancer patients (TARGET study) genotyped for SNPs in 56 genes. The most significant SNPs associated with grade ≥2 hypertension, diarrhea, dermatologic toxicities, and composite toxicity (any one of the toxicities) were tested for association with grade ≥2 toxicity in a validation set of 201 sorafenib-treated patients (Alliance/CALGB 80802). The validated SNP was tested for association with grade ≥2 toxicity in 107 (LCCC 1029) and 82 (Italian cohort) regorafenib-treated patients. SNP-toxicity associations were evaluated using logistic regression, and a meta-analysis between the studies was performed by inverse variance. Variant rs4864950 in KDR increased the risk of grade ≥2 composite toxicity in TARGET, Alliance/CALGB 80802, and the Italian cohort (meta-analysis p = 6.79 × 10-4, OR = 2.01, 95% CI 1.34-3.01). We identified a predictor of toxicities induced by VEGFR TKIs. CLINICALTRIALS.GOV IDENTIFIER: NCT00073307 (TARGET), NCT01015833 (Alliance/CALGB 80802), and NCT01298570 (LCCC 1029).

Plasma levels of VEGF-A and VCAM-1 as predictors of drug-induced hypertension in patients treated with VEGF pathway inhibitors.

AIMS: Hypertension is a common toxicity induced by vascular endothelial growth factor (VEGF) pathway inhibitors. There are no validated markers of hypertension induced by these drugs. METHODS: We previously discovered that cancer patients with lower plasma levels of angiopoietin-2, VCAM-1 and VEGF-A are at high risk of developing severe hypertension when treated with bevacizumab. This study aimed to validate the predictive value of these markers in pretreatment plasma samples of an additional cohort of 101 colorectal cancer patients treated with regorafenib. The levels of angiopoietin-2, VCAM-1 and VEGF-A were measured by enzyme-linked immunosorbent assay (ELISA). The association between proteins and grade ≥2 regorafenib-induced hypertension was performed by calculating the odds ratio (OR) from logistic regression. Using the optimal cut-point of each protein, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for hypertension were estimated. RESULTS: Lower levels of VCAM-1 (P = .015, OR = 3.11, 95% CI 1.27-8.08) and VEGF-A (P = .007, OR = 3.47, 95% CI 1.40-8.75) were associated with a higher risk of hypertension. Levels of angiopoietin-2 were not associated with hypertension. The multivariable model indicates an independent effect of VCAM-1 (P = .018, OR = 3.18, 95% CI 1.25-8.68) and VEGF-A (P = .008, OR = 3.77, 95% CI 1.44-10.21). The presence of low levels of both VCAM-1 and VEGF-A had an OR of 9.46 (95% CI 3.08-33.26, P = 1.70 × 10-4 ) for the risk of hypertension (sensitivity of 41.4%, specificity of 93.1%, PPV of 70.6% and NPV of 79.8%). CONCLUSIONS: This study confirmed the value of VCAM-1 and VEGF-A levels in predicting hypertension induced by regorafenib, another VEGF pathway inhibitor.

Prognostic and Predictive Biomarkers in Patients with Metastatic Colorectal Cancer Receiving Regorafenib.

Regorafenib is a tyrosine kinase inhibitor approved by the FDA for the treatment of patients with chemotherapy refractory metastatic colorectal cancer (mCRC). Regorafenib inhibits signaling through multiple receptors associated with angiogenesis, metastasis, and tumor immunity. Here, we report biomarker results from LCCC1029, a randomized, placebo-controlled, phase II trial of chemotherapy ± regorafenib in patients with second-line mCRC. A panel of 20 soluble protein biomarkers (termed the Angiome) was assessed in the plasma of 149 patients from the LCCC1029 trial both at baseline and along the treatment continuum. Baseline protein levels were analyzed for prognostic and predictive value for progression-free survival (PFS) and overall survival (OS). Changes in protein levels during treatment were analyzed for potential pharmacodynamic effects. Six markers (HGF, IL6, PlGF, VEGF-R1, OPN, and IL6R) were found to be prognostic for PFS. Nine markers (IL6, TIMP-1, PlGF, VCAM-1, ICAM-1, OPN, TSP-2, HGF, and VEGF-R1) were prognostic for OS. Higher baseline levels of OPN (P intx = 0.0167), VCAM-1 (P intx = 0.0216), and PDGF-AA (P intx = 0.0435) appeared to predict for PFS benefit from regorafenib compared with placebo. VCAM-1 was also potentially predictive of OS benefit from regorafenib compared with placebo (P intx = 0.0124). On-treatment changes of six markers reflected potential on-target effect of regorafenib. Consistent results were observed in an Italian cohort where 105 patients with late-stage mCRC received regorafenib monotherapy. The key findings of this study suggest that VCAM-1 may be a predictive biomarker for regorafenib benefit, while multiple protein markers may be prognostic of outcome in patients with mCRC.

Interaction of the membrane-inserted diphtheria toxin T domain with peptides and its possible implications for chaperone-like T domain behavior.

The T domain of diphtheria toxin is believed to aid the low-pH-triggered translocation of the partly unfolded A chain (C domain) through cell membranes. Recent experiments have suggested the possibility that the T domain aids translocation by acting as a membrane-inserted chaperone [Ren, J., et al. (1999) Science 284, 955-957]. One prediction of this model is that the membrane-inserted T domain should be able to interact with sequences that mimic unfolded proteins. To understand the basis of interaction of the membrane-inserted T domain with unfolded polypeptides, its interaction with water-soluble peptides having different sequences was studied. The membrane-inserted T domain was able to recognize helix-forming 23-residue Ala-rich peptides. In the presence of such peptides, hydrophobic helix 9 of the T domain underwent the previously characterized conformational change from a state exhibiting shallow membrane insertion to one exhibiting deep insertion. This conformational change was more readily induced by the more hydrophobic peptides that were tested. It did not occur at all in the presence a hydrophilic peptide in which alternating Ser and Gly replaced Ala or in the presence of unfolded hydrophilic peptides derived from the A chain of the toxin. Interestingly, a peptide with a complex sequence (RKE(3)KE(2)LMEW(2)KM(2)SETLNF) also interacted with the T domain very strongly. We conclude that the membrane-inserted T domain cannot recognize every unfolded amino acid sequence. However, it does not exhibit strong sequence specificity, instead having the ability to recognize and interact with a variety of amino acid sequences having moderate hydrophobicity. This recognition was not strictly correlated with the strength of peptide binding to the lipid, suggesting that more than just hydrophobicity is involved. Although it does not prove that the T domain functions as a chaperone, T domain recognition of hydrophobic sequences is consistent with it having polypeptide recognition properties that are chaperone-like.

Carboxypeptidase E, a prohormone sorting receptor, is anchored to secretory granules via a C-terminal transmembrane insertion.

Carboxypeptidase E (CPE) is a sorting receptor that directs the prohormone pro-opiomelanocortin (POMC) to the regulated secretory pathway, and is also a prohormone processing enzyme in neuro/endocrine cells. It has been suggested that the 25 C-terminal amino acids are necessary for the binding of CPE to secretory granule membranes, but its orientation in the membrane is not known. In this study, we examined the structure and orientation of the membrane-binding domain at the C-terminus of CPE. In vitro experiments using model membranes demonstrated that the last 22 amino acids of CPE (CP peptide) insert in a shallow orientation into lipid bilayers at low pH. Circular dichroism analysis indicated that the CP peptide adopts a partial alpha-helical configuration at low pH, and helix content increases when it is bound to lipid. Protease protection experiments, immunolabeling, and immunoisolation of intact secretory granules with a C-terminal antibody revealed a cytoplasmic domain in CPE, consistent with a transmembrane orientation of this protein. We conclude that the membrane-binding domain of CPE must adopt an alpha-helical configuration to bind to lipids, and that CPE may require another integral membrane "chaperone" protein to insert through the lipid bilayer in a transmembrane fashion.