Surfaceome profiling enables isolation of cancer-specific exosomal cargo in liquid biopsies from pancreatic cancer patients.

Background: Detection of circulating tumor DNA can be limited due to their relative scarcity in circulation, particularly while patients are actively undergoing therapy. Exosomes provide a vehicle through which cancer-specific material can be enriched from the compendium of circulating non-neoplastic tissue-derived nucleic acids. We carried out a comprehensive profiling of the pancreatic ductal adenocarcinoma (PDAC) exosomal 'surfaceome' in order to identify surface proteins that will render liquid biopsies amenable to cancer-derived exosome enrichment for downstream molecular profiling. Patients and methods: Surface exosomal proteins were profiled in 13 human PDAC and 2 non-neoplastic cell lines by liquid chromatography-mass spectrometry. A total of 173 prospectively collected blood samples from 103 PDAC patients underwent exosome isolation. Droplet digital PCR was used on 74 patients (136 total exosome samples) to determine baseline KRAS mutation call rates while patients were on therapy. PDAC-specific exosome capture was then carried out on additional 29 patients (37 samples) using an antibody cocktail directed against selected proteins, followed by droplet digital PCR analysis. Exosomal DNA in a PDAC patient resistant to therapy were profiled using a molecular barcoded, targeted sequencing panel to determine the utility of enriched nucleic acid material for comprehensive molecular analysis. Results: Proteomic analysis of the exosome 'surfaceome' revealed multiple PDAC-specific biomarker candidates: CLDN4, EPCAM, CD151, LGALS3BP, HIST2H2BE, and HIST2H2BF. KRAS mutations in total exosomes were detected in 44.1% of patients undergoing active therapy compared with 73.0% following exosome capture using the selected biomarkers. Enrichment of exosomal cargo was amenable to molecular profiling, elucidating a putative mechanism of resistance to PARP inhibitor therapy in a patient harboring a BRCA2 mutation. Conclusion: Exosomes provide unique opportunities in the context of liquid biopsies for enrichment of tumor-specific material in circulation. We present a comprehensive surfaceome characterization of PDAC exosomes which allows for capture and molecular profiling of tumor-derived DNA.

Adenoid size is related to severity but not the number of episodes of obstructive apnea in children.

OBJECTIVE: The objective of this study was to determine the extent to which adenotonsillar hypertrophy contributes to the severity of obstructive sleep apnea (OSA) in children. STUDY DESIGN: Thirty-three consecutive children who were referred to a sleep disorders center for evaluation of suspected OSA had standard lateral neck roentgenography performed. Adenoid size was determined by measuring the adenoidal-nasopharyngeal (AN) ratio. Tonsil size was quantitated on physical examination. The severity of OSA was determined by full-night polysomnography in the sleep laboratory. RESULTS: All of the patients reported snoring with trouble breathing, apneas, or both problems witnessed by a parent. The patients' respiratory disturbance index ranged from 0 to 95.3 (mean +/- SD 12.5 +/- 9.1). The patients' AN ratio ranged from 0.48 to 0.98 (0.76 +/- 0.14); 30 (91%) of the 33 patients had AN ratios greater than published normal means, and 16 (48%) had AN ratios more than 2 standard deviations above published means. Although the AN ratio and tonsil size did not predict the number of apneas, a significant relationship was seen between the AN ratio and the duration of obstructive apneas (r = 0.48, p < 0.01). Obesity (percent ideal body weight) was the only independent predictor for the number of respiratory events per hour of sleep (r = 0.49, p < 0.01). Percent ideal body weight was also the major predictor of the lowest oxyhemoglobin saturation (r = -0.58, p < 0.0001), but the AN ratio also contributed to the variance in saturation, with a correlation coefficient (r) of 0.69 for the two factors (p < 0.0001). CONCLUSION: Lymphoid hyperplasia affects the severity of apnea more than the number of obstructive apneas. The pathophysiologic characteristics of OSA in children probably involve complex interactions between pharyngeal size and mechanics.