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OBJECTIVE Mild traumatic brain injury (mTBI) is a major cause of emergency room (ER) admission. Thirty percent of mTBI patients have postconcussion syndrome (PCS), and 15% have symptoms for over a year. This population is underdiagnosed and does not receive appropriate care. The authors proposed a fast and inexpensive fluorometric measurement of circulating cell-free DNA (cfDNA) as a biomarker for PCS. cfDNA is a proven, useful marker of a variety of acute pathological conditions such as trauma and acute illness. METHODS Thirty mTBI patients were recruited for this prospective single-center trial. At admission, patients completed questionnaires and blood was drawn to obtain cfDNA. At 3–4 months after injury, 18 patients returned for cognitive assessments with questionnaires and the Color Trails Test (CTT). The fast SYBR Gold assay was used to measure cfDNA. RESULTS Seventeen men and 13 women participated in this trial. The mean ± SD age was 50.9 ± 13.9 years. Of the 18 patients who returned for cognitive assessment, one-third reported working fewer hours, 4 (22.2%) changed their driving patterns, and 5 (27.7%) reduced or stopped performing physical activity. The median cfDNA level of the mTBI group was greater than that of the matched healthy control group (730.5 vs 521.5 ng/ml, p = 0.0395). Admission cfDNA concentration was negatively correlated with performance on the CTT1 and CTT2 standardized tests (r = −0.559 and −0.599), meaning that greater cfDNA level was correlated with decreased cognitive performance status. The performance of the patients with normal cfDNA level included in the mTBI group was similar to that of the healthy participants. In contrast, the increased cfDNA group (> 800 ng/ml) had lower scores on the CTT tests than the normal cfDNA group (p < 0.001). Furthermore, patients with moderate/severe cognitive impairment according to CTT1 results had a greater median cfDNA level than the patients with scores indicating mild impairment or normal function (1186 vs 473.5 ng/ml, p = 0.0441, area under the receiver operating characteristic curve = 0.8393). CONCLUSIONS The data from this pilot study show the potential to use cfDNA, as measured with a fast test, as a biomarker to screen for PCS in the ER. A large-scale study is required to establish the value of cfDNA as an early predictor of PCS.

Torticollis is encountered often in the paediatric setting and should be considered a presenting symptom, rather than a diagnosis. Aetiologies of torticollis are numerous, and the nomenclature describing underlying diagnosis can be confusing. Furthermore, children with torticollis typically present in the first instance to primary or secondary care rather than to the subspecialist. These factors can contribute to erroneous treatment of this patient-group which could be time critical in some instances. In this review, we discuss the common causes for torticollis and propose a simple clinical assessment tool and early management scheme that will assist in the differential-diagnosis and treatment pathway of this challenging condition.Conclusion: Torticollis can be the initial presentation of various conditions. The diagnosis and management tools provided in this article can aid in guiding paediatricians as to the correct initial management, imaging, and specialist referral. What is Known: • Torticollis in childhood is a very common presenting symptom with numerous aetiologies. • Management is complex, requires multiple clinical and imaging examinations, and is usually performed by non-specialized professionals. What is New: • A new, simple clinical-assessment tool under the acronym PINCH designed to aid paediatric general practitioners in diagnosing correctly the aetiology of torticollis. • A practical management scheme to aid in the treatment pathway of children with torticollis.

INTRODUCTION Hydrocephalus persists in 10-40% of children with posterior fossa tumours (PFT). A delay in commencement of adjuvant therapy (AT) can negatively influence survival. The objective of this study was to determine whether postoperative cerebrospinal fluid (CSF) diversion procedures caused potentially preventable delays in AT. METHODS A retrospective study of children diagnosed with PFT requiring AT from 2004 to 2018 from two large centres was conducted. Data on histology, timing of ventriculo-peritoneal shunt (VPS) insertion, and AT was collected. The modified Canadian Preoperative Prediction Rule for Hydrocephalus (mCPPRH) score was calculated. The primary outcome was delay in AT beyond 40 days post-resection. Progression-free and overall survival were assessed. RESULTS Out of 196 primary PFT resections, 144 fitted the inclusion criteria. Mean age was 6.57 ± 4.62. Histology was medulloblastoma (104), ependymoma (27), and others (13). Forty patients had a VPS inserted; 17 of these experienced a delay in AT. A total of 104 patients were not shunted; 15 of these had delayed AT (p = 0.0007). Patients who had a VPS insertion had longer intervals from surgery to commencement of AT (34.5 vs 30.8, p = 0.05). There was no significant difference in mCPPRH score between those who had a VPS (4.03) and those who did not (3.61; p = 0.252). Multivariable linear regression modelling did not show a significant effect of VPS or mCPPRH on progression-free survival or OS. CONCLUSION CSF diversion procedures may cause a preventable delay in the initiation of adjuvant therapy. Early post-operative VP shunt insertion, rather than a 'wait and see policy' should be considered in order to reduce this delay.

Focal cortical dysplasia (FCD) is a malformation of cortical development and is associated with drug-resistant epilepsy. Standard indication for epilepsy surgery is drug resistance (as defined by the ILAE). Given the high incidence of drug resistance in these children, this delay may not be warranted. The aim of the study was to determine the proportion of patients with a presumed FCD who develop drug resistance, and evaluate post-operative outcomes.This study incorporated a survey within a regional paediatric epilepsy network and a retrospective database review of a paediatric epilepsy centre serving the network to identify children with epilepsy and a presumed FCD on MRI.The survey revealed that 86% of the patients with epilepsy and presumed FCD on MRI within the network were referred to our centre. Of 139 paediatric patients included in the study, 131 (94.2%) had drug-resistant epilepsy. One hundred and ten (83.9%) patients were referred to epilepsy surgery, of whom 97 underwent surgery. Of 92 with one-year postoperative follow-up, 59.8% had an Engel Class 1 (seizure-free) outcome. Concordance of location between MRI and ictal EEG was strongly associated with Engel Class 1 outcome (p0.001), as was older age at seizure onset (p=0.03). Time from diagnosis to surgery, number of medications, type of surgery and histology were not associated with improved outcome.Our data suggest that most children presenting with seizures and a radiological diagnosis of FCD will develop drug-resistant epilepsy and are candidates for epilepsy surgery. The main outcome predictors are the correlation between MRI and ictal EEG localization and age at onset. This suggests that patients with FCD and epilepsy may be considered for surgery before traditional criteria of drug resistance are met. This change in practice has the potential to improve quality of life and cognitive function, and reduce burden on epilepsy services.

Torticollis is encountered often in the paediatric setting and should be considered a presenting symptom, rather than a diagnosis. Aetiologies of torticollis are numerous, and the nomenclature describing underlying diagnosis can be confusing. Furthermore, children with torticollis typically present in the first instance to primary or secondary care rather than to the subspecialist. These factors can contribute to erroneous treatment of this patient-group which could be time critical in some instances. In this review, we discuss the common causes for torticollis and propose a simple clinical assessment tool and early management scheme that will assist in the differential-diagnosis and treatment pathway of this challenging condition.Conclusion: Torticollis can be the initial presentation of various conditions. The diagnosis and management tools provided in this article can aid in guiding paediatricians as to the correct initial management, imaging, and specialist referral. What is Known: • Torticollis in childhood is a very common presenting symptom with numerous aetiologies. • Management is complex, requires multiple clinical and imaging examinations, and is usually performed by non-specialized professionals. What is New: • A new, simple clinical-assessment tool under the acronym PINCH designed to aid paediatric general practitioners in diagnosing correctly the aetiology of torticollis. • A practical management scheme to aid in the treatment pathway of children with torticollis.

Background Spontaneous intracerebral hematoma (ICH) is a common disease with a dismal overall prognosis. Recent development of minimally invasive ICH evacuation techniques has shown promising results. Commercially available tubular retractors are commonly used for minimally invasive ICH evacuation yet are globally unavailable. Methods A novel U.S. $7 cost-effective, off-the-shelf, atraumatic tubular retractor for minimally invasive intracranial surgery is described. Patients with acute spontaneous ICH underwent microsurgical tubular retractor–assisted minimally invasive ICH evacuation using the novel retractor. Patient outcome was retrospectively analyzed and compared with open surgery and with commercial tubular retractors. Results Ten adult patients with spontaneous supratentorial ICH and median preoperative Glasgow Coma Scale score of 10 were included. ICH involved the frontal lobe, parietal lobe, occipitotemporal region, and solely basal ganglia in 3, 3, 2, and 2 patients, respectively. Mean preoperative ICH volume was 80 mL. Mean residual hematoma volume was 8.7 mL and mean volumetric hematoma reduction was 91% (median, 94%). Seven patients (70%) underwent >90% volumetric hematoma reduction. The total median length of hospitalization was 26 days. On discharge, the median Glasgow Coma Scale score was 12.5 (mean, 11.7). Thirty to 90 days' follow-up data were available for 9 patients (90%). The mean follow-up modified Rankin Scale score was 3.7 and 5 patients (56%) had a modified Rankin Scale score of 3. Conclusions The novel cost-effective tubular retractor and microsurgical technique offer a safe and effective method for minimally invasive ICH evacuation. Cost-effective tubular retractors may continue to present a valid alternative to commercial tubular retractors.

Numerous case studies have reported spontaneous regression of recognized metastases following primary tumor excision, but underlying mechanisms are elusive. Here, we present a model of regression and latency of metastases following primary tumor excision and identify potential underlying mechanisms.Using MDA-MB-231These results demonstrate regression and latency of micro-metastases following primary tumor excision and a crucial role for primary tumor secretome in promoting early metastatic growth in MDA-MB-231

Background Numerous case studies have reported spontaneous regression of recognized metastases following primary tumor excision, but underlying mechanisms are elusive. Here, we present a model of regression and latency of metastases following primary tumor excision and identify potential underlying mechanisms. Results Using MDA-MB-231HM human breast cancer cells that express highly sensitive luciferase, we monitored early development stages of spontaneous metastases in BALB/c nu/nu mice. Removal of the primary tumor caused marked regression of micro-metastases, but not of larger metastases, and in vivo supplementation of tumor secretome diminished this regression, suggesting that primary tumor-secreted factors promote early metastatic growth. Correspondingly, MDA-MB-231HM-conditioned medium increased in vitro tumor proliferation and adhesion and reduced apoptosis. To identify specific mediating factors, cytokine array and proteomic analysis of MDA-MB-231HM secretome were conducted. The results identified significant enrichment of angiogenesis, growth factor binding and activity, focal adhesion, and metalloprotease and apoptosis regulation processes. Neutralization of MDA-MB-231HM-secreted key mediators of these processes, IL-8, PDGF-AA, Serpin E1 (PAI-1), and MIF, each antagonized secretome-induced proliferation. Moreover, their in vivo simultaneous blockade in the presence of the primary tumor arrested the development of micro-metastases. Interestingly, in the METABRIC cohort of breast cancer patients, elevated expression of Serpin E1, IL-8, or the four factors combined predicted poor survival. Conclusions These results demonstrate regression and latency of micro-metastases following primary tumor excision and a crucial role for primary tumor secretome in promoting early metastatic growth in MDA-MB-231HM xenografts. If generalized, such findings can suggest novel approaches to control micro-metastases and minimal residual disease.

Background: While patient-derived xenografts (PDXs) offer a powerful modality for translational cancer research, a precise evaluation of how accurately patient responses correlate with matching PDXs in a large, heterogeneous population is needed for assessing the utility of this platform for preclinical drug-testing and personalized patient cancer treatment. Patients and methods: Tumors obtained from surgical or biopsy procedures from 237 cancer patients with a variety of solid tumors were implanted into immunodeficient mice and whole-exome sequencing was carried out. For 92 patients, responses to anticancer therapies were compared with that of their corresponding PDX models. Results: We compared whole-exome sequencing of 237 PDX models with equivalent information in The Cancer Genome Atlas database, demonstrating that tumorgrafts faithfully conserve genetic patterns of the primary tumors. We next screened PDXs established for 92 patients with various solid cancers against the same 129 treatments that were administered clinically and correlated patient outcomes with the responses in corresponding models. Our analysis demonstrates that PDXs accurately replicate patients' clinical outcomes, even as patients undergo several additional cycles of therapy over time, indicating the capacity of these models to correctly guide an oncologist to treatments that are most likely to be of clinical benefit. Conclusions: Integration of PDX models as a preclinical platform for assessment of drug efficacy may allow a higher success-rate in critical end points of clinical benefit.

Background: Screening of patients for cancer-driving mutations is now used for cancer prognosis, remission scoring and treatment selection. Although recently emerged targeted next-generation sequencing-based approaches offer promising diagnostic capabilities, there are still limitations. There is a pressing clinical need for a well-validated, rapid, cost-effective mutation profiling system in patient specimens. Given their speed and cost-effectiveness, quantitative PCR mutation detection techniques are well suited for the clinical environment. The qBiomarker mutation PCR array has high sensitivity and shorter turnaround times compared with other methods. However, a direct comparison with existing viable alternatives are required to assess its true potential and limitations. Methods: In this study, we evaluated a panel of 117 patient-derived tumour xenografts by the qBiomarker array and compared with other methods for mutation detection, including Ion AmpliSeq sequencing, whole-exome sequencing and droplet digital PCR. Results: Our broad analysis demonstrates that the qBiomarker's performance is on par with that of other labour-intensive and expensive methods of cancer mutation detection of frequently altered cancer-associated genes, and provides a foundation for supporting its consideration as an option for molecular diagnostics. Conclusions: This large-scale direct comparison and validation of currently available mutation detection approaches is extremely relevant for the current scenario of precision medicine and will lead to informed choice of screening methodologies, especially in lower budget conditions or time frame limitations.

The necessity and timing of early postoperative imaging (POI) are debated in many studies. Despite the consensus that early POI does not change patient management, these examinations are routinely performed. This is the first prospective study related to POI. Our aims were to assess the necessity of early POI in asymptomatic patients and to verify accuracy of the presented algorithm.This was an algorithm-based prospective single-center study. The algorithm addressed preoperative, perioperative, and postoperative considerations, including estimated pathology type, device placement, and postoperative neurologic change. Early computed tomography scans were obtained in all patients, but if postoperative algorithm indications did not recommend a scan, the treating team was blinded to them, and patient management was conducted based on clinical examinations alone. A neuroradiologist and study-independent neurosurgeon reviewed all the scans.Of 103 enrolled patients, 88 remained asymptomatic, and 15 experienced symptoms postoperatively. Pathology was present on POI in 1% of the asymptomatic patients and 53% of the symptomatic patients (P0.001). In the asymptomatic group, no treatment modifications were made postoperatively. Blinding of the surgical team was not removed, and 20% of the symptomatic patients returned to the operating room because of imaging and neurologic findings. The goal of5% algorithm failure was reached with statistical significance.In asymptomatic postoperative patients in whom early imaging is not performed for oncologic indications, device placement verification, or similar reasons, POI is unnecessary and does not change the management of these patients.

The coordination of a sequence of actions, to be performed in a linear temporal order in a distributed system, is studied. While in asynchronous message-passing systems such ordering of events requires the construction of message chains based on Lamport's happened-before relation, this is no longer true in the presence of time bounds on message delivery. Given such bounds, the mere passage of time can provide information about the occurrence of events at remote sites, without the need for explicit confirmation. A new causal structure called the centipede is introduced, and it is shown that centipedes must exist in every execution where linear ordering of actions is ensured. Centipedes capture the subtle interplay between the explicit information obtained via message chains, and the indirectly derived information gained by the passage of time, given the time bounds. Centipedes are defined using two relations. One is called syncausality, a slight generalisation of the happened-before relation. The other is a novel bound guarantee relation among events, that is based on the bounds on message transmission. In a precise sense, centipedes play a role in the synchronous setting analogous to that played by message chains in asynchronous systems. Our study is based on a knowledge-based analysis of distributed coordination. Temporally linear coordination is reduced to nested knowledge (knowledge about knowledge). Obtaining nested knowledge of a spontaneous event is, in turn, shown to require the existence of an appropriate centipede.

Post traumatic dural sinus vein stenosis has been rarely described in pediatric population. We present a case of a 9-year-old child that had sustained a head injury after a fall from height causing an acute epidural hematoma compressing the dominant sigmoid sinus. The patient had developed sub acutely signs and symptoms of increased intracranial pressure. Prophylactic treatment with anticoagulants was initiated despite the presence of an intracranial bleeding. Clinical and radiological improvements were achieved. We had also reviewed the literature regarding this uncommon entity and discussed other existing diagnostic and therapeutic alternatives. Further gathering of information is essential in order to form a therapeutic protocol.

Mutations in the gene encoding the cystic fibrosis transmembrane regulator (CFTR) have been reported to increase the risk of recurrent acute pancreatitis in patients with pancreas divisum. We assessed the CFTR gene in a young male patient with pancreas divisum and recurrent acute pancreatitis. Magnetic resonance cholangiopancreatography and computed tomography revealed that the patient had pancreas divisum, with an enlarged and tortuous pancreatic duct; he also had positive results from the cystic fibrosis sweat test. Genetic analysis did not identify any common CFTR mutations, but did show that he was homozygous for the 5T allele in intron 8 IVS8 5T-12TG (which affects splicing at intron 8). Endoscopic sphincterotomy and stenting of papilla minor was performed. The IVS8 5T-12TG variant has been associated with abnormal organ development, therefore it is possible that CFTR has an important role in the development of the pancreatic duct. We propose this patient has recurrent acute pancreatitis resulting from a developmental defect associated with a suboptimal CFTR function.

Chlamydia pneumoniae and human cytomegalovirus (HCMV) are intracellular pathogens able to infect hepatocytes, causing an increase in serum triglycerides and cholesterol levels due to the production of inflammatory cytokines. We investigated whether these pathogens could interfere with cholesterol metabolism by affecting activity of hepatic cholesterol 7α-hydroxylase ( CYP7A1 ) promoter. CYP7A1 is the rate-limiting enzyme responsible for conversion of cholesterol to bile acids, which represents the main route of cholesterol catabolism. A straightforward dual-reporter bioluminescent assay was developed to simultaneously monitor CYP7A1 transcriptional regulation and cell viability in infected human hepatoblastoma HepG2 cells. C. pneumoniae and HCMV infection significantly decreased CYP7A1 promoter activity in a dose-dependent manner, with maximal inhibitions of 33 ± 10% and 32 ± 4%, respectively, at a multiplicity of infection of 1. To support in vitro experiments, serum cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides and glucose levels were also measured in Balb/c mice infected with C. pneumoniae. Serum cholesterol and triglycerides also increased in infected mice compared with controls. Although further investigation is required, this work presents the first experimental evidence that C. pneumoniae and HCMV inhibit CYP7A1 gene transcription in the cultured human hepatoblastoma cell line.

A minor change to the standard epistemic logical language, replacing K i with K 〈i,t〉 where t is an explicit time instance, gives rise to a generalized and more expressive form of knowledge and common knowledge operators. We investigate the communication structures that are necessary for such generalized epistemic states to arise, and the inter-agent coordination tasks that require such knowledge. Previous work has established a relation between linear event ordering and nested knowledge, and between simultaneous event occurrences and common knowledge. In the new, extended, formalism, epistemic necessity is decoupled from temporal necessity. Nested knowledge and event ordering are shown to be related even when the nesting order of the operators does not match the temporal order of occurrence. The generalized form of common knowledge does not correspond to simultaneity. Rather, it corresponds to a notion of tight coordination, of which simultaneity is an instance.

Screening of patients for cancer-driving mutations is now used for cancer prognosis, remission scoring and treatment selection. Although recently emerged targeted Next Generation Sequencing (NGS) - based approaches provide accurate results and offer promising diagnostic capabilities, there are still limitations which impede their adoption for large-scale population-based screening. There is a pressing clinical need for a well-validated, rapid, cost-effective and accurate mutation profiling system with optimal analytical performance in patient specimens. Given their speed, and cost-effectiveness, real-time, quantitative qPCR mutation detection techniques are well suited for the clinical environment. The novel qBiomarker somatic mutation PCR array has high sensitivity and shorter turnaround times compared to other methods. However a direct comparison to existing viable alternatives is required to assess its true potential and limitations. In this study, we extensively evaluated a panel of 117 patient-derived tumor xenografts (PDX) by the qBiomarker array and directly compared its efficacy with that of other routinely used methods for mutation detection, including Ion AmpliSeq sequencing, whole exome sequencing (WES), and ultra-sensitive droplet digital PCR (ddPCR) genotyping. Our comprehensive analysis demonstrates that qBiomarker's performance is on par with that of other routinely used but more complex, labor-intensive and expensive methods of cancer mutation detection, and provides a foundation for advancing the adoption of qBiomarker assay for cancer driving mutation profiling in clinical diagnostics. Furthermore, a large-scale direct comparison of different mutation detection approaches will lead to informed choice of screening methodologies, especially in lower budget conditions or timeframe limitations. Citation Format: Mariana Brait, Evgeny Izumchenko, Luciane Kagohara, Samuel Long, Piotr Wysocki, Brian Faherty, Elana Fertig, Tin Khor, Elizabeth Bruckheimer, Gilson Baia, Daniel Ciznadija, Ido Sloma, Ido Ben-Zvi, Keren Paz, David Sidransky. Validation of qBiomarker as an accurate and efficient mutation detection method in a comprehensive analysis of patient-derived tumor xenografts. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3640.

Due to the importance of intestinal transport in pharmacological studies and the emerging role of intestinal signalling activity in the gut-liver axis, we have developed a new method to investigate intestinal transport and liver signalling using cell and serum free mesenteric perfusion system in the rat. The method regarding bile acid active absorption was validated, then, the portal venous content was examined for fibroblast growth factor 15(FGF15), a putative signalling protein produced by the ileal enterocytes following bile acid absorption. After isolation and cannulation of the relevant vessels (abdominal aorta and portal vein), the abdominal aorta and the terminal ileum were infused with respectively Krebs-Ringer solution and tauroursodeoxycholate (TUDCA) and the absorption was assessed by its recovery in the portal vein. After immunoblot, liquid chromatography and mass spectrometry analysis were performed both on gel bands digestion products and on portal outflow samples in order to evaluate if negligible amounts of FGF15 were present in the portal circulation. TUDCA absorption was efficient, intestinal morphology and oxygen consumption were normal. Despite accurate analysis, we could not find FGF15. Our method proved to be reliable for studying the active bile acid absorption. It is also suitable to identify molecules produced by enterocytes and transferred to the portal circulation in response to absorption of different substances such as nutrients or drugs. Since FGF15 was not recovered we suggest the possibilities that this protein is produced in very little amounts, poorly transferred outside the cell, or that it is extremely unstable and rapidly degraded.

Lamport's happened-before relation provides a starting point for an enquiry into causal relations in synchronous systems. We define the ordered response problem, a natural coordination task. By analyzing solutions to this task we arrive at the Centipede Theorem, that gives a concise characterization of synchronous causality.

Background Patient-derived xenograft (PDX) models, also known as Champions TumorGraft® models, maintain the complex intra-tumoral biology of the primary tumor. Over 250 of the Champions models, ranging over a wide variety of solid tumors and passaging generations, have been analyzed using whole exome sequencing (WES) and RNA sequencing (RNAseq). SNPs, InDels and copy number alterations (CNAs) data have been generated for each model, following the Genome Analysis Toolkit (GATK). While several publications compare small numbers of PDX models and human tumors on the molecular level, this is the first known comprehensive analysis whereby the molecular fidelity of the PDX platform is corroborated across several cancer types and throughout different mouse generations. Method and Results First, we compared PDXs to their human original counterparts using a preliminary group of four PDX models with available matching human patient WES data. Patient tumor source included dedifferentiated liposarcoma, synovial sarcoma, renal cell carcinoma and squamous cell carcinoma of the lung. PDX passages ranged from 2 to 4. We compared called mutations and a high percentage of identified human tumor mutations were present in the PDX models (42-82%), with the lowest scoring model also showing signs of normal contamination in the human tumor sample. For CNAs in oncogenic sites, we saw an average of 65% of human tumor alterations recurring in the PDX models. This was observed, despite inherent difficulties due to exome based CNA analysis methods. Encouraged by the individual patients results, we subjected our largest (per cancer type) PDX cohorts to a molecular comparison with the equivalent TCGA cohorts. More than 200 of the sequenced models, grouped into colorectal adenocarcinoma (COADREAD), lung adenocarcinoma (LUAD), breast carcinoma (BRCA), head and neck squamous cell carcinoma (HNSC) and ovarian serous carcinoma (OV) cohorts were compared. We applied mutation category (MC) and significantly mutated genes (SMG) analysis, as well as comparison of mutation population frequencies for TCGA SMG. Results showed high correlation between the TCGA and the Champions PDX cohorts, although the level of matching varied between cancer types. For instance, COADREAD was highly correlative, while other cancer types, such as BRCA, showed bias toward CpG site mutations. In SMG analysis and population frequency analysis, major SMGs recur across the cohorts, while, as expected, weaker signals from the TCGA were often missed in the smaller cohorts. Conclusion Detailed comparison of several PDX models to the human tumor counterpart demonstrated high fidelity, not only at the gene level but also the mutation and CNA level. Cohort comparisons were correlative as well, but a certain bias was discerned in both MC and SMG analyses. There could be several causes for this, including statistical artifacts due to small cohort sizes, clinical and demographic differences between the Champions and TCGA patient profiles, or biological factors such as clonal selection and engraftment pressure. Further analysis is ongoing to better understand the model at a molecular level and maximize its utility as a robust translational research tool. Citation Format: Ido Ben-Zvi, Ido Sloma, Tin Khor, Daniel Ciznadija, Amanda Katz, David Vasquez, David Sidransky, Keren Paz. Molecular fidelity of patient derived xenograft (PDX) models to original human tumor and to the cancer genome atlas (TCGA). [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A14.

Patient-derived xenograft (PDX) models maintain the complex intra-tumoral biology and heterogeneity of an intact malignancy, as well as the interplay with stromal components and other cells fluxing into the tumor environment. This intrinsic cross-talk between different elements of the tumor makes PDX models a superior tool for translational drug discovery research and personalized oncology studies. Champions PDX models were originally developed for personalizing cancer treatments through the different Champions clinical programs. These models accurately reflect the population of patients enrolling in clinical trials. We describe herein our extensive TumorBank of PDX models, a valuable resource for translational oncology research to predetermine target populations for intervention with novel therapeutics in specific cancer subtypes. Tumor tissue from over 950 patients with a variety of primary and metastatic solid malignancies, across all ages and ethnicities and encompassing both treatment-naïve and heavily-pretreated individuals, has been implanted into immunodeficient mice with successful engraftment observed in ∼72% of cases. Comprehensive and translational-relevant clinical annotations have been maintained for these PDX models, including patient demographics, disease stage, anatomic location, tumor grade and histology, and treatment history. Importantly, whole exome and RNA sequencing, tissue histopathology, and protein immunohistochemistry have all been applied to 297 of these models. Finally, 70 of the models were screened against the corresponding patient's treatment used in the clinic, demonstrating a sensitivity of 98%, specificity of 76%, positive predictive value of 89% and negative predictive value of 96%. This wealth of information can be accessed through the Champions TumorGraft Database. The combination of extensive molecular and clinical annotation, together with opportunities for unlimited prospective preclinical testing, makes Champions TumorBank a pioneering resource for pharmaceutical companies seeking to identify target populations for therapeutic intervention. Citation Format: Tin O. Khor, Ido Ben Zvi, Amanda Katz, David Vasquez-Dunddel, Ido Sloma, Daniel Ciznadija, David Sidransky, Keren Paz. A patient-centric repository of PDX models for translational oncology research. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3219. doi:10.1158/1538-7445.AM2015-3219