A239 PATIENT OUTCOMES AFTER ENDOSCOPIC STENT INSERTION FOR MALIGNANT BILIARY OBSTRUCTION: A QUALITY ASSURANCE STUDY

Background

Management of pancreaticobiliary malignancy is complex and multi-disciplinary. Decompression of malignant biliary obstruction (MBO) is preferentially achieved with endoscopic retrograde cholangiopancreatography (ERCP) and biliary stent placement. This may improve the quality of life for patients with unresectable disease and improve outcomes in resectable/borderline-resectable disease.

Purpose

To assess quality outcomes in patients undergoing biliary stenting for MBO.

Method

This is a retrospective chart audit of patients referred to the University of Alberta Hospital (UAH) for suspected or confirmed MBO. The primary outcome was clinical success (reduction in bilirubin of >50% at 30 days). Secondary outcomes were technical success, type of stent used, need for re-intervention, adverse events (AEs), time from stent placement to surgery or cancer centre assessment, and survival.

Result(s)

Between January 2020 and June 2022, 222 patients (102 female, 46%) with a mean age of 70±1 years (range 34-93 years) underwent 290 ERCPs. The cause of MBO was pancreatic cancer in 130 (59%), cholangiocarcinoma in 32 (14%), ampullary cancer in 9 (4%), and others in 51 (23%).

Technical success for stent insertion on first ERCP was achieved in 180/222 patients (81%) with only brushings performed in 2. Of the 40 patients (18%) with unsuccessful ERCP, further success was achieved by repeat ERCP (8), percutaneous transhepatic drainage (PTC, 15), PTC with rendezvous ERCP (1), surgical decompression (3), and endoscopic ultrasound-guided biliary drainage (1). No biliary drainage was performed in 12 patients. Overall, ERCP with stent insertion was technically successful in 188/222 patients (85%).

A total of 233 biliary stents were inserted (38 plastic, 195 metal). Clinical success was achieved in 20/38 patients (53%) with plastic stents and 151/181 patients (83%) with metal stents (Χ2 17.4 p<0.05).

Adverse events were encountered in 33 patients (11%) with stent migration occurring in 8 (3%), cholangitis in 7 (2%), post-ERCP pancreatitis in 7 (2%), post-sphincterotomy bleeding in 4 (1%), and death in 2 (1%). Re-intervention was required in 36 patients (20%) after initial ERCP with successful stent placement. The re-intervention rate was significantly higher with plastic stents (14/27, 52%) than with metal stents (22/153, 14%) after initial ERCP (Χ2 20.1 p<0.001).

The overall survival was a mean of 249±16 days (5-967) for patients with plastic stents and 248± 16 days (1-959) for those with metal stents. Survival was significantly worse in patients with unresectable disease vs resectable/borderline-resectable disease (Log rank 38.89, p<0.001), Figure 1.

Image

Conclusion(s)

In MBO, metal stents appear to provide significantly better biliary drainage, with less need for re-intervention, but do not appear to be associated with any survival benefit over plastic stents. We hope that this quality assurance project will help in the development of a regional management pathway for optimizing the care of patients presenting with MBO.

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Disclosure of Interest

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Cohort profile: 'Biomarkers of Personalised Medicine' (BioPersMed): a single-centre prospective observational cohort study in Graz/Austria to evaluate novel biomarkers in cardiovascular and metabolic diseases

PURPOSE

Accumulating evidence points towards a close relationship between cardiovascular, endocrine and metabolic diseases. The BioPersMed Study (Biomarkers of Personalised Medicine) is a single-centre prospective observational cohort study with repetitive examination of participants in 2-year intervals. The aim is to evaluate the predictive impact of various traditional and novel biomarkers of cardiovascular, endocrine and metabolic pathways in asymptomatic individuals at risk for cardiovascular and/or metabolic disease.

PARTICIPANTS

Between 2010 and 2016, we recruited 1022 regional individuals into the study. Subjects aged 45 years or older presenting with at least one traditional cardiovascular risk factor or manifest type 2 diabetes mellitus (T2DM) were enrolled. The mean age of the participants was 57±8 years, 55% were female, 18% had T2DM, 33% suffered from arterial hypertension, 15% were smokers, 42% had hyperlipidaemia, and only 26% were at low cardiovascular risk according to the Framingham 'Systematic COronary Risk Evaluation'.

FINDINGS TO DATE

Study procedures during screening and follow-up visits included a physical examination and comprehensive cardiovascular, endocrine, metabolic, ocular and laboratory workup with biobanking of blood and urine samples. The variety of assessed biomarkers allows a full phenotyping of individuals at cardiovascular and metabolic risk. Preliminary data from the cohort and relevant biomarker analyses were already used as control population for genomic studies in local and international research cooperation.

FUTURE PLANS

Participants will undergo comprehensive cardiovascular, endocrine and metabolic examinations for the next decades and clinical outcomes will be adjudicated prospectively.

"Dangerous liaisons: NAFLD and liver fibrosis increase cardiovascular risk in HIV"

OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is strongly associated with cardiovascular disease in the general population. We aimed to assess the impact of NAFLD and liver fibrosis on intermediate-high cardiovascular risk in people living with HIV.

METHODS

We included people living with HIV from three cohorts. NAFLD and significant liver fibrosis were defined using transient elastography: controlled attenuation parameter ≥288 dB/m and liver stiffness measurement ≥7.1 kPa, respectively. Cardiovascular risk was assessed with the atherosclerotic cardiovascular disease (ASCVD) risk estimator in patients aged between 40 and 75 years and categorised as low if <5%, borderline if 5%-7.4%, intermediate if 7.5%-19.9% and high if ≥20% or with the presence of a previous cardiovascular event. Patients with hepatitis B and/or hepatitis C virus co-infection, alcohol abuse and unreliable transient elastography measurements were excluded. Predictors of intermediate-high cardiovascular risk were investigated in multivariable analysis by logistic regression and also by stratifying according to body mass index (BMI; cut-offs of 25 and 30 kg/m² ) and age (cut-off of 60 years).

RESULTS

Of 941 patients with HIV alone included, 423 (45%), 128 (13.6%), 260 (27.6%) and 130 (13.8%) were categorised as at low, borderline, intermediate and high ASCVD risk, respectively. Predictors of intermediate-high ASCVD risk were NAFLD (adjusted odds ratio [aOR] 2.11; 95% confidence interval [CI] 1.40-3.18; p < 0.001), liver fibrosis (aOR 1.64; 95% CI 1.03-2.59; p = 0.034), duration of HIV (aOR 1.04; 95% CI 1.02-1.06; p < 0.001), and previous exposure to thymidine analogues and/or didanosine (aOR 1.54; 95% CI 1.09-2.18; p = 0.014). NAFLD was also associated with higher cardiovascular risk in normoweight patients (aOR 2.97; 95% CI 1.43-6.16; p = 0.003), in those with BMI <30 kg/m² (aOR 2.30; 95% CI 1.46-3.61; p < 0.001) and in those aged <60 years (aOR 2.19; 95% CI 1.36-3.54; p = 0.001).

CONCLUSION

Assessment of cardiovascular disease should be targeted in people living with HIV with NAFLD and/or significant liver fibrosis, even if they are normoweight and young.

A31 OUTCOMES OF PATIENTS UNDERGOING REPEAT VIDEOCAPSULE ENDOSCOPY (VCE) PRESENTING WITH OBSCURE GASTROINTESTINAL BLEEDING (OGIB)

Background

Videocapsule Endoscopy (VCE) as well as balloon-assisted enteroscopy (BAE) are useful tools in the diagnosis and management of obscure gastrointestinal bleeding (OGIB). There is limited data assessing the diagnostic yield of VCE in subjects with OGIB according to different subtypes: 1) obscure overt 2) inactive overt and 3) active overt.

Aims

We evaluated the diagnostic yield and outcomes of patients undergoing a second VCE in OGIB.

Methods

This is a retrospective analysis of all patients who underwent more than one VCE completed at the University of Alberta from January 1, 2015 to August 31, 2021. Demographic and background information was collected including previous endoscopy results, cross-sectional imaging, and subsequent interventions. Patient data was analyzed according to subtype of OGIB at presentation.

Results

During the study period, there were 59 subjects who met inclusion criteria. The indication for VCE was recurrent iron deficiency anemia (IDA), active OGIB, and/or inactive OGIB in 38 subjects. The median time to VCE after initial endoscopic evaluation was 61 days. Median age of cases was 61.5 years and 49% were female.

Initial VCE had clinically significant positive findings in 68% of cases (Table 1). The diagnostic yield was 75%, 56% and 74% in active OGIB, inactive OGIB, and IDA, respectively. Active bleeding or fresh blood was present in 33% of VCEs for active OGIB compared to 11% of inactive OGIB and 13% of subjects with IDA.

At second VCE investigation, there were positive findings in 42% of cases. Findings on second VCE differed from initial VCE in 17 of 38 cases. Findings that changed clinical management were found in 76% of patients after first and second VCE.

BAEs were performed in 20 subjects after VCE, with therapeutics applied in 75%. The most common findings were arteriovenous malformations (AVMs) (65%) and erosions/ulcers (15%).

Conclusions

The diagnostic yield of VCE is high in appropriately selected patients and did not significantly differ in patients with IDA, active, and inactive OGIB. Serial VCE is appropriate for the investigation of suspected recurrent small bowel bleeding when initial workup is nondiagnostic.

Funding Agencies

None

A93 USEFULNESS OF A NOVEL SMARTPHONE APP IN GASTROINTESTINAL ENDOSCOPY TO TRACK PROCEDURE NUMBERS AND THERAPEUTIC INTERVENTIONS

Background

Endoscopy teaching is an integral part of gastroenterology (GI) training. Though the number of completed endoscopic procedures does not equate competency, procedure tracking is useful for monitoring an individual’s learning progress. Currently, procedure tracking is typically done on an informal basis using paper or electronic spreadsheets. These methods are non-standardized and may not be shareable between trainees and their programs.

Endostation is a smartphone app created by the University of Alberta Therapeutic Endoscopy Program to facilitate the tracking of endoscopic procedures. The app allows trainees to record the number of endoscopies and details such as cecal intubation (CI), ERCP cannulation, and therapeutic interventions. Data can be accessed by users via the app and website (www.endostation.ca), allowing for close monitoring of trainees’ learning progress.

Aims

Our primary objective was to evaluate the usefulness of the app for tracking the number of endoscopic procedures and therapeutic interventions. Our secondary objective was to evaluate the acquisition of endoscopy skills based on quality endoscopic parameters such as CI rate and ERCP cannulation rate.

Methods

One therapeutic endoscopy fellow and two GI residents were recruited for the study. Participants were asked to document their procedures over the study period (9-month for therapeutic endoscopy fellow, 12-month for GI residents). Total number of procedures was summed for each trainee. Acquisition of endoscopy skills was tracked by comparing success rates of CI and ERCP cannulation at different points within the study period.

Results

The therapeutic endoscopy fellow recorded 415 cannulation attempts, 209 sphincterotomies, 282 stone extractions, 71 plastic stent placements, and 37 metal stent placements. There was a significant difference in the cannulation success rate when comparing the 1^st trimester and the 3^rd trimester of the study period (68% vs 85%; p= 0.0012) (Fig 1).

The two GI residents respectively recorded 335 and 170 colonoscopies plus 454 and 305 gastroscopies. Resident 1 recorded 58 polypectomies, 9 esophageal variceal banding, and 16 non-variceal hemostasis. Resident 2 recorded 17 polypectomies, 12 esophageal variceal banding, and 9 non-variceal hemostasis. The CI success rate was significantly higher for both residents when comparing the first 4 months of training vs the last 4 months [24% vs 88% for resident 1 (p=0.00001); 15% vs 42% for resident 2 (p= 0.001)] (Fig 1).

Conclusions

The smartphone app (Endostation) was a useful tool for endoscopic procedure tracking. Data from the app was useful in demonstrating improvement in CI rate and ERCP cannulation rate over the study period.

Funding Agencies

None

Cyclic GMP modulating drugs in cardiovascular diseases: Mechanism-based network pharmacology

Mechanism-based therapy centred on the molecular understanding of disease-causing pathways in a given patient is still the exception rather than the rule in medicine, even in cardiology. However, recent successful drug developments centred around the second messenger cyclic guanosine-3′-5′-monophosphate (cGMP), which is regulating a number of cardiovascular disease modulating pathways, are about to provide novel targets for such a personalized cardiovascular therapy. Whether cGMP breakdown is inhibited or cGMP synthesis is stimulated via guanylyl cyclases or their upstream regulators in different cardiovascular disease phenotypes, the outcomes seem to be so far uniformly protective. Thus, a network of cGMP-modulating drugs has evolved that act in a mechanism-based, possibly causal manner in a number of cardiac conditions. What remains a challenge is the detection of cGMPopathy endotypes amongst cardiovascular disease phenotypes. Here, we review the growing clinical relevance of cGMP and provide a glimpse into the future on how drugs interfering with this pathway may change how we treat and diagnose cardiovascular diseases altogether.

Prevalence, Predictors, and Severity of Lean Nonalcoholic Fatty Liver Disease in Patients Living With Human Immunodeficiency Virus

BACKGROUND

The burden of nonalcoholic fatty liver disease (NAFLD) is growing in people living with human immunodeficiency virus (HIV). NAFLD is associated with obesity; however, it can occur in normoweight (lean) patients. We aimed to investigate lean NAFLD in patients living with HIV.

METHODS

We included patients living with HIV mono-infection from 3 prospective cohorts. NAFLD was diagnosed by transient elastography (TE) and defined as controlled attenuation parameter ≥248 dB/m, in absence of alcohol abuse. Lean NAFLD was defined when a body mass index was <25 kg/m2. Significant liver fibrosis was defined as TE ≥7.1 kPa. The presence of diabetes, hypertension, or hyperlipidemia defined metabolically abnormal patients.

RESULTS

We included 1511 patients, of whom 57.4% were lean. The prevalence of lean NAFLD patients in the whole cohort was 13.9%. NAFLD affected 24.2% of lean patients. The proportions of lean NAFLD patients who were metabolically abnormal or had elevated alanine aminotransferase (ALT) were higher than among those who were lean patients without NAFLD (61.9% vs 48.9% and 36.7% vs 24.2%, respectively). Lean NAFLD patients had a higher prevalence of significant liver fibrosis than lean patients without NAFLD (15.7% vs 7.6%, respectively). After adjusting for sex, ethnicity, hypertension, CD4 cell count, nadir CD4 <200µ/L, and time since HIV diagnosis, predictors of NAFLD in lean patients were age (adjusted OR [aOR], 1.29; 95% confidence interval [CI], 1.04-1.59), high triglycerides (aOR, 1.34; 95% CI, 1.11-1.63), and high ALT (aOR, 1.15; 95% CI, 1.05-1.26), while a high level of high-density lipoprotein cholesterol was protective (aOR, 0.45; 95% CI, .26-.77).

CONCLUSIONS

NAFLD affects 1 in 4 lean patients living with HIV mono-infection. Investigations for NAFLD should be proposed in older patients with dyslipidemia and elevated ALT, even if normoweight.

A142 TRENDS IN HELICOBACTER PYLORI TREATMENT AND CURE IN EDMONTON: 2015–2020

Background

Therapies for Helicobacter pylori infection have changed significantly over time due to changes in resistance patterns. In 2016, the Toronto H. pylori consensus guidelines recommended treatment for 14 days. First-line therapies are concomitant therapy with a proton-pump inhibitor (PPI) and clarithromycin-amoxicillin-metronidazole (CLAMET) or bismuth-based quadruple therapy (PPI-bismuth-metronidazole-tetracycline, PBMT). Second and/or third line therapies are PBMT or PPI-amoxicillin-levofloxacin (PAL) and the fourth line PPI-amoxicillin-rifabutin (PAR) for 10 days.

Aims

To describe and compare the efficacy of current treatment regimens for H. pylori infection in Edmonton.

Methods

This retrospective study reviewed records of patients treated for H. pylori infection at the University of Alberta Hospital (UAH) in Edmonton, Alberta from January 1, 2015 - November 1, 2020. Diagnosis of H. pylori infection and test-of-cure were documented with a positive urea breath test, stool antigen test, histology on endoscopy, or positive culture. Patients who had no post-treatment testing were excluded. The per protocol efficacy of different regimens was calculated as well as cumulative success rates when given as 2nd, 3rd or 4th line therapy.

Results

Overall, 170 of 237 (71.7 %) confirmed H. pylori cases achieved cure. The majority were female (64%) and 113 (48%) were born outside of Canada. CLAMET initiated at UAH had the highest success rate 41/45 (91%), and in referred patients who were previously treated was successful as first-line therapy in 45/70 (64%). Overall success rate of regimens were as follows (Table 1): CLAMET 49/98 (50%), PBMT 45/114 (40%), PAL 33/99 (33%), and PAR 16/31 (51%). Alternative regimens were not successful 27/223 (12%). Cultures and resistance profiles were available for 53 cases that failed initial treatment. Resistance to clarithromycin (84%), metronidazole (48%), and levofloxacin (41%) was highly prevalent (Figure 1).

Conclusions

Test-of-cure is important to verify H. pylori eradication as antibiotic resistance is common to clarithromycin, metronidazole, and levofloxacin when prior treatments failed. These results support the H. pylori treatment regimens recommended by the Toronto consensus guidelines.

Funding Agencies

None

Nonalcoholic Fatty Liver Disease and the Development of Metabolic Comorbid Conditions in Patients With Human Immunodeficiency Virus Infection

BACKGROUND

Cardiovascular and liver disease are main causes of death in people with human immunodeficiency virus (HIV) (PWH). In HIV-uninfected patients, nonalcoholic fatty liver disease (NAFLD) is associated with incident metabolic complications. We investigated the effect of NAFLD on development of metabolic comorbid conditions in PWH.

METHODS

We included PWH undergoing a screening program for NAFLD using transient elastography. NAFLD was defined as a controlled attenuation parameter ≥248 dB/m with exclusion of other liver diseases. Incident diabetes, hypertension, dyslipidemia, and chronic kidney disease were investigated using survival analysis and Cox proportional hazards.

RESULTS

The study included 485 HIV-monoinfected patients. During a median follow-up of 40.1 months (interquartile range, 26.5-50.7 months), patients with NAFLD had higher incidences of diabetes (4.74 [95% confidence interval, 3.09-7.27] vs 0.87 [.42-1.83] per 100 person-years) and dyslipidemia (8.16 [5.42-12.27] vs 3.99 [2.67-5.95] per 100 person-years) than those without NAFLD. With multivariable analysis, NAFLD was an independent predictor of diabetes (adjusted hazard ratio, 5.13; 95% confidence interval, 2.14-12.31) and dyslipidemia (2.35; 1.34-4.14) development.

CONCLUSIONS

HIV-monoinfected patients with NAFLD are at higher risk of incident diabetes and dyslipidemia. Early referral strategies and timely management of metabolic risk may improve outcomes.

High-Sensitivity Cardiac Troponin T for Risk Stratification in Patients With Embolic Stroke of Undetermined Source

Background and Purpose:

Optimal secondary prevention for patients with embolic stroke of undetermined source (ESUS) remains unknown. We aimed to assess whether high-sensitivity cardiac troponin T (hs-cTnT) levels are associated with major vascular events and whether hs-cTnT may identify patients who benefit from anticoagulation following ESUS.

Methods:

Data were obtained from the biomarker substudy of the NAVIGATE ESUS trial, a randomized controlled trial testing the efficacy of rivaroxaban versus aspirin for secondary stroke prevention in ESUS. Patients were dichotomized at the hs-cTnT upper reference limit (14 ng/L, Gen V, Roche Diagnostics). Cox proportional hazard models were computed to explore the association between hs-cTnT, the combined cardiovascular end point (recurrent stroke, myocardial infarction, systemic embolism, cardiovascular death), and recurrent ischemic stroke.

Results:

Among 1337 patients enrolled at 111 participating centers in 18 countries (mean age 67±9 years, 61% male), hs-cTnT was detectable in 95% and at/above the upper reference limit in 21%. During a median follow-up of 11 months, the combined cardiovascular end point occurred in 68 patients (5.0%/y, rivaroxaban 28 events, aspirin 40 events; hazard ratio, 0.67 [95% CI, 0.41–1.1]), and recurrent ischemic stroke occurred in 50 patients (4.0%/y, rivaroxaban 16 events, aspirin 34 events, hazard ratio 0.45 [95% CI, 0.25–0.81]). Annualized combined cardiovascular end point rates were 8.2% (9.5% rivaroxaban, 7.0% aspirin) for those above hs-cTnT upper reference limit and 4.8% (3.1% rivaroxaban, 6.6% aspirin) below with a significant treatment modification ( P =0.04). Annualized ischemic stroke rates were 4.7% above hs-cTnT upper reference limit and 3.9% below, with no suggestion of an interaction between hs-cTnT and treatment ( P =0.3).

Conclusions:

In patients with ESUS, hs-cTnT was associated with increased cardiovascular event rates. While fewer recurrent strokes occurred in patients receiving rivaroxaban, outcomes were not stratified by hs-cTn results. Our findings support using hs-cTnT for cardiovascular risk stratification but not for decision-making regarding anticoagulation therapy in patients with ESUS.

Registration:

URL: https://www.clinicaltrials.gov . Unique identifier: NCT02313909.

Multicenter Evaluation of Independent High-Throughput and RT-qPCR Technologies for the Development of Analytical Workflows for Circulating miRNA Analysis

Background: Among emerging circulating biomarkers, miRNA has the potential to detect lung cancer and follow the course of the disease. However, miRNA analysis deserves further standardization before implementation into clinical trials or practice. Here, we performed international ring experiments to explore (pre)-analytical factors relevant to the outcome of miRNA blood tests in the context of the EU network CANCER-ID. Methods: Cell-free (cfmiRNA) and extracellular vesicle-derived miRNA (EVmiRNA) were extracted using the miRNeasy Serum/Plasma Advanced, and the ExoRNeasy Maxi kit, respectively, in a plasma cohort of 27 NSCLC patients and 20 healthy individuals. Extracted miRNA was investigated using small RNA sequencing and hybridization platforms. Validation of the identified miRNA candidates was performed using quantitative PCR. Results: We demonstrate the highest read counts in healthy individuals and NSCLC patients using QIAseq. Moreover, QIAseq showed 15.9% and 162.9% more cfmiRNA and EVmiRNA miRNA counts, respectively, in NSCLC patients compared to healthy control samples. However, a systematic comparison of selected miRNAs revealed little agreement between high-throughput platforms, thus some miRNAs are detected with one technology, but not with the other. Adding to this, 35% (9 of 26) of selected miRNAs in the cfmiRNA and 42% (11 of 26) in the EVmiRNA fraction were differentially expressed by at least one qPCR platform; about half of the miRNAs (54%) were concordant for both platforms. Conclusions: Changing of (pre)-analytical methods of miRNA analysis has a significant impact on blood test results and is therefore a major confounding factor. In addition, to confirm miRNA biomarker candidates screening studies should be followed by targeted validation using an independent platform or technology.

Hepatocyte Growth Factor Receptor overexpression predicts reduced survival but its targeting is not effective in unselected HNSCC patients

BACKGROUND

MET has emerged as target in head and neck squamous cell carcinoma (HNSCC). However, clinical data on MET inhibition in HNSCC are limited.

METHODS

HNSCC biopsies and cell lines were tested for MET activity. The response of cell lines to BAY-853474 was tested in proliferation assays. The prognostic value of MET expression was also analyzed.

RESULTS

HNSCC cell lines do not respond to MET inhibition. MET-dependent gastric cancer cell lines have much higher levels of MET expression and phosphorylation than HNSCC cell lines. Clinical samples of HNSCC contain much less MET than responsive models.

CONCLUSIONS

No clinical response to MET inhibitors in monotherapy may be expected in unselected cases of HNSCC. Only selected patients with MET amplifications should be treated with MET inhibitors. Patients with increased MET immunoreactivity have shorter overall survival. MET might be useful as marker for the detection of patients with more aggressive types of HNSCC.

A prospective cohort study to identify and evaluate endotypes of venous thromboembolism: Rationale and design of the Genotyping and Molecular Phenotyping in Venous ThromboEmbolism project (GMP-VTE)

Several clinical, genetic and acquired risk factors for venous thromboembolism (VTE) have been identified. However, the molecular pathophysiology and mechanisms of disease progression remain poorly understood. This is reflected by uncertainties regarding the primary and secondary prevention of VTE and the optimal duration of antithrombotic therapy. A growing body of literature points to clinically relevant differences between VTE phenotypes (e.g. deep vein thrombosis (DVT) versus pulmonary embolism (PE), unprovoked versus provoked VTE). Extensive links to cardiovascular, inflammatory and immune-related morbidities are testament to the complexity of the disease. The GMP-VTE project is a prospective, multi-center cohort study on individuals with objectively confirmed VTE. Sequential data sampling was performed at the time of the acute event and during serial follow-up investigations. Various data levels (e.g. clinical, genetic, proteomic and platelet data) are available for multi-dimensional data analyses by means of advanced statistical, bioinformatic and machine learning methods. The GMP-VTE project comprises n = 663 individuals with acute VTE (mean age: 60.3 ± 15.9 years; female sex: 42.8%). In detail, 28.4% individuals (n = 188) had acute isolated DVT, whereas 71.6% subjects (n = 475) had PE with or without concomitant DVT. In the study sample, 28.9% (n = 129) of individuals with PE and 30.1% (n = 55) of individuals with isolated DVT had a recurrent VTE event at the time of study enrolment. The systems-oriented approach for the comprehensive dataset of the GMP-VTE project may generate new biological insights into the pathophysiology of VTE and refine our current understanding and management of VTE.

Test-Retest Reliability of Non-Invasive Cardiac Output Measurement during Exercise in Healthy Volunteers in Daily Clinical Routine

Background

Thoracic bioreactance (TB), a noninvasive method for the measurement of cardiac output (CO), shows good test-retest reliability in healthy adults examined under research and resting conditions.

Objective

In this study, we evaluate the test-retest reliability of CO and cardiac power (CPO) output assessment during exercise assessed by TB in healthy adults under routine clinical conditions.

Methods

25 test persons performed a symptom-limited graded cycling test in an outpatient office on two different days separated by one week. Cardiorespiratory (power output, VO_2peak) and hemodynamic parameters (heart rate, stroke volume, CO, mean arterial pressure, CPO) were measured at rest and continuously under exercise using a spiroergometric system and bioreactance cardiograph (NICOM, Cheetah Medical).

Results

After 8 participants were excluded due to measurement errors (outliers), there was no systematic bias in all parameters under all conditions (effect size: 0.2-0.6). We found that all noninvasively measured CO showed acceptable test-retest-reliability (intraclass correlation coefficient: 0.59-0.98; typical error: 0.3-1.8). Moreover, peak CPO showed better reliability (intraclass correlation coefficient: 0.80-0.85; effect size: 0.9-1.1) then the TB CO, thanks only to the superior reliability of MAP (intraclass correlation coefficient: 0.59-0.98; effect size: 0.3-1.8).

Conclusion

Our findings preclude the clinical use of TB in healthy subject population when outliers are not identified.

Abstract 3985: Dynamic changes of tumor-derived extracellular vesicles and related RNAs in blood samples of NSCLC patients

Liquid biopsy is defined as molecular analysis of rare cells or cell-free nucleic acids circulating in blood or in other biofluids. The concept of liquid biopsy aims at closely monitoring the status of a disease or treatment efficacy in a simple, fast, cost efficient way and at any point in time with minimal risk and burden for the patient. It has been suggested that the most reproducible approach to investigate “liquid” mRNAs would be to focus on cell-free extracellular vesicle (EV)-transcripts rather than on circulating cell-free mRNAs, as the former are well protected from degradation and therefore more stable. However, the volumes of available blood samples can be limiting for molecular analysis and rare cells as well as cell-free nucleic acids are normally present in low abundance. Therefore, detection of rare events or quantification of limited material requires robust, highly sensitive technologies like droplet digital PCR (ddPCR).

In this pilot study, we investigated the absolute expression of 10 EV-transcripts typically involved in cancer development and chemotherapy resistance in longitudinal serum samples of 13 non-small cell lung cancer (NSCLC) patients (age range 37-76 years) treated with cisplatin at the Department of Inner Medicine II, University of Ulm, between May 2011 and August 2012.

Blood samples were collected at baseline, after 3-6 months and after 9-12 months of chemotherapy from patients showing objective clinical response. Then, EV-RNAs were isolated by sequentially processing obtained serum samples with miRCURY® exosome kit and miRNeasy kit (both Qiagen, Hilden, Germany). Afterwards, the status of selected EV-transcripts was investigated via ddPCR (Biorad, Milan, Italy).

After start of chemotherapy, we observed a downregulation of at least 2-fold of the following potentially cancer-related EV-transcripts : PTEN, ERBB2, FOSL1, IL-8, MET, RPS27A, SF3B1 and of the following housekeeping EV-mRNAs: ACTB, HIST1H3H and HSPA1A, in all patients. Interestingly, in none of patients' samples, the expression of EV-AKT1 and of EV-PD-L1 transcripts could be detected.

Our preliminary results demonstrates significant dynamic changes of cancer-related EV-mRNA expression in serum samples of NSCLC patients during cisplatin treatment, thus suggesting a potential overall decrease of EVs in response to chemotherapy. Moreover, despite the small amounts of mRNA in extracellular vesicles from patient blood, using ddPCR differential mRNA levels could be determined in patient serum and expand the scope of biomarker analysis of EVs.

This work is supported by IMI JU & EFPIA (grand no. 115749, CANCER-ID). Samples from patients and healthy volunteers, respectively, were collected under signed informed consent.

Citation Format: Rita Lampignano, Martin Neumann, Vera Kloten, Nina Kessler, Anna Babayan, Laura Keller, Ines Stevic, Klaus Pantel, Thomas Krahn, Thomas Schlange, for the IMI CANCER-ID consortium. Dynamic changes of tumor-derived extracellular vesicles and related RNAs in blood samples of NSCLC patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3985.

Multicenter Evaluation of Circulating Plasma MicroRNA Extraction Technologies for the Development of Clinically Feasible Reverse Transcription Quantitative PCR and Next-Generation Sequencing Analytical Work Flows

BACKGROUND

In human body fluids, microRNA (miRNA) can be found as circulating cell-free miRNA (cfmiRNA), as well as secreted into extracellular vesicles (EVmiRNA). miRNAs are being intensively evaluated as minimally invasive liquid biopsy biomarkers in patients with cancer. The growing interest in developing clinical assays for circulating miRNA necessitates careful consideration of confounding effects of preanalytical and analytical parameters.

METHODS

By using reverse transcription quantitative real-time PCR and next-generation sequencing (NGS), we compared extraction efficiencies of 5 different protocols for cfmiRNA and 2 protocols for EVmiRNA isolation in a multicentric manner. The efficiency of the different extraction methods was evaluated by measuring exogenously spiked cel-miR-39 and 6 targeted miRNAs in plasma from 20 healthy individuals.

RESULTS

There were significant differences between the tested methods. Although column-based extraction methods were highly effective for the isolation of endogenous miRNA, phenol extraction combined with column-based miRNA purification and ultracentrifugation resulted in lower quality and quantity of isolated miRNA. Among all extraction methods, the ubiquitously expressed miR-16 was represented with high abundance when compared with other targeted miRNAs. In addition, the use of miR-16 as an endogenous control for normalization of quantification cycle values resulted in a decreased variability of column-based cfmiRNA extraction methods. Cluster analysis of normalized NGS counts clearly indicated a method-dependent bias.

CONCLUSIONS

The choice of plasma miRNA extraction methods affects the selection of potential miRNA marker candidates and mechanistic interpretation of results, which should be done with caution, particularly across studies using different protocols.

Circulating endothelial cells as biomarker for cardiovascular diseases

BACKGROUND

Endothelial dysfunction is involved in several cardiovascular diseases. Elevated levels of circulating endothelial cells (CECs) and low levels of endothelial progenitor cells (EPCs) have been described in different cardiovascular conditions, suggesting their potential use as diagnostic biomarkers for endothelial dysfunction. Compared to typical peripheral blood leukocyte subsets, CECs and EPCs occur at very low frequency. The reliable identification and characterization of CECs and EPCs is a prerequisite for their clinical use, however, a validated method to this purpose is still missing but a key for rare cell events.

OBJECTIVES

To establish a validated flow cytometric procedure in order to quantify CECs and EPCs in human whole blood.

METHODS

In the establishment phase, the assay sensitivity, robustness, and the sample storage conditions were optimized as prerequisite for clinical use. In a second phase, CECs and EPCs were analyzed in heart failure with preserved (HFpEF) and reduced (HFrEF) ejection fraction, in arterial hypertension (aHT), and in diabetic nephropathy (DN) in comparison to age-matched healthy controls.

RESULTS

The quantification procedure for CECs and EPCs showed high sensitivity and reproducibility. CEC values resulted significantly increased in patients with DN and HFpEF in comparison to healthy controls. CEC quantification showed a diagnostic sensitivity of 90% and a sensitivity of 68.0%, 70.4%, and 66.7% for DN, HFpEF, and aHT, respectively.

CONCLUSION

A robust and precise assay to quantify CECs and EPCs in pre-clinical and clinical studies has been established. CEC counts resulted to be a good diagnostic biomarker for DN and HFpEF.

Characteristics of circulating endothelial cells obtained from non-ST-segment elevation myocardial infarction patients with additional diastolic dysfunction of left ventricle observed in echocardiography

BACKGROUND

Circulating endothelial cells (CEC) may be used to find new strategies for the early di-agnosis of cardiovascular diseases. The major objective of the project is to broaden knowledge of CEC biology by determining their phenotypic characteristics. The additional aim is to clarify whether on the basis of these information it is possible to identify the origin of CEC release (from various cardiovascular compartments).

METHODS

Circulating endothelial cells were collected from arterial blood prior to angiography, as well as from arterial and venous blood obtained after angiography/coronary angioplasty, from 18 patients with non-ST-segment elevation myocardial infarction (NSTEMI). CECs were quantified by flow cytometry and defined as Syto16 (dye)+, CD45dim/neg, CD31+ and CD146+. The additional CD36+ was establish as a marker of endothelial cells released from small vessels of the microcirculation.

RESULTS

The total number of CECs increased significantly after the percutaneous transluminal coronary angioplasty (PTCA) in the arterial system. Number of CECs isolated at similar time points (after invasive procedure) did not differ significantly between arteries and veins, but the number of CD36+ CECs after coronary angioplasty was significantly higher in the venous system, than in the arterial system.

CONCLUSIONS

The number of CD36+ in artery samples obtained after coronary angioplasty (PTCA) had tendency to be decreased (in comparison to the sample obtained before angiography). It was major difference between those who had PTCA performed vs. those who had not.

Abstract 2389: Role of MET in head and neck cancer

Introduction c-MET is a well-known target due to its amplification and overexpression in gastric cancer and NSCLC. Overexpression has also been reported for Head and Neck Cancer (HNSCC), but initial clinical trials with MET inhibitors in HNSCC have not been successful.

Methods We investigated the expression level of MET in HNSCC and also characterized the molecular activity level based on the phosphorylation of the intracellular adaptor protein docking site, Tyrosine-1349. In a second larger cohort, we tested expression of MET and correlate it with follow-up data in order to test the prognostic relevance of MET expression in gastric cancer. All clinical samples were all obtained in compliance with clinical regulations and informed consent of every patient.

Results We found MET clearly overexpressed in HNSCC. However, the signaling activity of MET was not elevated compared to normal adjacent tissue. To test the relevance of MET for growth of HNSCC cells, we tested the activity of BAY 853474 in a panel of HNSCC cell lines. In contrast to gastric cancer control cell lines which had low nanomolar IC50 values, none of the 12 HNSCC cell lines was sensitive to MET inhibition. This was in contrast to their sensitivity to Cisplatin/Fluoruracil as positive control. Compared to MET dependent cell lines from gastric cancer, HNSCC cell lines had 10 fold less MET expression. The phosphorylation was two orders of magnitude below that of responder cell lines. On the molecular level, we also compared the properties of the HNSCC cell lines with that of fresh frozen tumor biopsies from 50 patients. In this analysis, it became evident that clinical samples had strikingly lower MET expression and phosphorylation even compared to the HNSCC cell lines. Based on these findings, a clinical response to MET inhibitors cannot be expected. In a larger cohort of several hundred patients, we are currently testing whether the elevated MET expression may still be prognostic for progression and/or survival. It appears possible that MET expression may give a growth advantage to tumor cells although it is clearly not fulfilling the criteria for an oncogenic driver in this indication. The significant overexpression of MET in tumor tissue and the very strong overexpression in cell lines compared to clinical samples show that MET expression gives a selective advantage to the tumor cells. We will show whether this advantage results in shorter time to progression or overall survival.

Conclusion We show that MET expression in HNSCC cell lines is not representative for the clinical situation. HNSCC does not overexpress Met and the molecular activity is low. MET is devalidated as therapeutic target in HNSCC. An analysis of the prognostic value of MET expression in HNSCC will follow and presented at the AACR meeting in 2018.

Citation Format: Thomas Schlange, Martin Khan, Sami Khaznadar, arndt schmitz, Thomas Krahn, Oliver von Ahsen. Role of MET in head and neck cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2389.

Abstract 1594: A fast and sensitive workflow to screen therapy-relevant mutations in circulating tumor cells and quantification of cancer-associated extracellular vesicle-derived mRNA in plasma of cancer patients

Liquid biopsy can be considered a test that detects rare cells or nucleic acids circulating in blood or in other biofluids. The concept of liquid biopsy aims to monitor the status of a disease or treatment efficacy in a simple, fast, cost efficient way and at any point in time with acceptable risk and burden for the patient. However, the volumes of available blood samples can be quite limited and rare cells as well as circulating nucleic acids are normally present in low abundance. Therefore, detection of rare events or the quantification of limited material requires robust, highly sensitive technologies like droplet digital PCR (ddPCR).

Here, a novel workflow is presented combining the effective enrichment of rare cells using the Parsortix microfluidic filtration system with the analysis by ddPCR. Ten or 100 cells of NSCLC cell line NCI-H441 were spiked into a suspension of 100k NCI-H1563 cells or healthy EDTA blood. The resulting cell suspensions were processed using the microfluidic device Parsortix to enrich cell factions by size and deformability. Enriched cell fractions were harvested or lysed directly in the Parsortix cassette. Genomic DNA was prepared from all cell fractions. NCI-H441 cells are heterozygous for KRAS G12V and TP53 R158L mutations, while NCI-H1563 cells do not contain the mutations. Ten cells or less were enough to detect KRAS G12V or TP53 R158L mutations in a standard blood sample (7-10 ml). This combined workflow enables quantification of circulating tumor cells and analysis for therapy relevant point mutations in a fast, EpCAM independent manner.

Additionally, extracellular vesicle derived mRNA (EVmRNA) isolated from either cell culture supernatant or plasma from cancer patients was analyzed to demonstrate the suitability of ddPCR for assessing specific EVmRNA as biomarkers in different cancer types. In 13 NSCLC and 17 metastatic breast cancer plasma samples the levels of epithelial and oncogene EVmRNA, including EpCAM, ERBB2 or FGFR3 were determined and compared to healthy control plasma. Levels of potentially cancer-associated EVmRNA were only detectable in plasma from cancer patients, but not in healthy controls. Samples from patients and healthy volunteers, respectively, were collected under signed informed consent.

We demonstrated, that ddPCR allows the verification of therapy relevant point mutations in CTCs has the potential to be used as a screening approach. Moreover, despite the small amounts of mRNA in extracellular vesicles from patient blood, using ddPCR differential mRNA levels can be determined in patient plasma and enable and expand the scope of biomarker analysis from EVs.

This work is supported by IMI JU & EFPIA (grand no. 115749).

Citation Format: Martin H. Neumann, Sebastian Bender, Thomas Krahn, Thomas Schlange. A fast and sensitive workflow to screen therapy-relevant mutations in circulating tumor cells and quantification of cancer-associated extracellular vesicle-derived mRNA in plasma of cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1594.

EGFR overexpression is not common in patients with head and neck cancer. Cell lines are not representative for the clinical situation in this indication

Background

Based on expression data, Epidermal Growth Factor Receptor (EGFR) emerged as therapeutic target in Head and Neck Cancer but clinical efficacy of EGFR inhibitors was very limited. We reinvestigated the EGFR expression and activation status necessary for response in cell lines and compared that to clinical samples.

Methods

Clinical samples of head and neck squamous cell carcinoma (HNSCC, n=63), mostly from late stage (IV) and poorly or undifferentiated character and cultured cell lines (n=14) were tested by immunohistochemistry (IHC) (n=55) and sandwich immunoassays (n=63) for expression and phosphorylation of EGFR (Tyrosine-1173). Response of 14 different HNSCC cell lines to Erlotinib was tested in proliferation assays.

Results

Most HNSCC cell lines respond to Erlotinib. EGFR is phosphorylated in these cell lines. Resistant cell lines display very low level EGFR expression and phosphorylation. EGFR activity in clinical samples is significantly below that observed in cell lines. In clinical samples, EGFR is not overexpressed on the single cellular level. We show similar levels of EGFR expression in growing keratinocytes and tumor cells.

Conclusions

Cell lines are not representative of the clinical situation in HNSCC. Larger studies should investigate whether patient subgroups with activating EGFR mutations or overexpression can be identified.

In situ analysis of FGFR2 mRNA and comparison with FGFR2 gene copy number by dual-color in situ hybridization in a large cohort of gastric cancer patients

BACKGROUND

Fibroblast growth factor receptor (FGFR2) has been proposed as a target in gastric cancer. However, appropriate methods to select patients for anti-FGFR2 therapies have not yet been established.

METHODS

We used in situ techniques to investigate FGFR2 mRNA expression and gene amplification in a large cohort of 1036 Japanese gastric cancer patients. FGFR2 mRNA expression was determined by RNAscope. FGFR2 gene amplification was determined by dual-color in situ hybridization (DISH).

RESULTS

We successfully analyzed 578 and 718 samples by DISH and RNAscope, respectively; 2% (12/578) showed strong FGFR2 gene amplification (FGFR2:CEN10 >10); moderate FGFR2 gene amplification (FGFR2:CEN10 <10; ≥2) was detected in 8% (47/578); and high FGFR2 mRNA expression of score 4 (>10 dots/cell and >10% of positive cells with dot clusters under a 20× objective) was seen in 4% (29/718). For 468 samples, both mRNA and DISH data were available. FGFR2 mRNA expression levels were associated with gene amplification; FGFR2 mRNA levels were highest in the highly amplified samples (n = 12). All highly amplified samples showed very strong FGFR2 mRNA expression (dense clusters of the signal visible under a 1× objective). Patients with very strong FGFR2 mRNA expression showed more homogeneous FGFR2 mRNA expression compared to patients with lower FGFGR2 mRNA expression. Gastric cancer patients with tumors that had an FGFR2 mRNA expression score of 4 had shorter RFS compared with score 0-3 patients.

CONCLUSION

RNAscope and DISH are suitable methods to evaluate FGFR2 status in gastric cancer. Formalin-fixed paraffin-embedded (FFPE) tissue slides allowed evaluation of the intratumor heterogeneity of these FGFR2 biomarkers.

Isolation of circulating tumor cells from pancreatic cancer by automated filtration

It is now widely recognized that the isolation of circulating tumor cells based on cell surface markers might be hindered by variability in their protein expression. Especially in pancreatic cancer, isolation based only on EpCAM expression has produced very diverse results. Methods that are independent of surface markers and therefore independent of phenotypical changes in the circulating cells might increase CTC recovery also in pancreatic cancer. We compared an EpCAM-dependent (IsoFlux) and a size-dependent (automated Siemens Healthineers filtration device) isolation method for the enrichment of pancreatic cancer CTCs. The recovery rate of the filtration based approach is dramatically superior to the EpCAM-dependent approach especially for cells with low EpCAM-expression (filtration: 52%, EpCAM-dependent: 1%). As storage and shipment of clinical samples is important for centralized analyses, we also evaluated the use of frozen diagnostic leukapheresis (DLA) as source for isolating CTCs and subsequent genetic analysis such as KRAS mutation detection analysis. Using frozen DLA samples of pancreatic cancer patients we detected CTCs in 42% of the samples by automated filtration.

Detection of MET mRNA in gastric cancer in situ. Comparison with immunohistochemistry and sandwich immunoassays

Determination of predictive biomarkers by immunohistochemistry (IHC) relies on antibodies with high selectivity. RNA in situ hybridization (RNA ISH) may be used to confirm IHC and may potentially replace it if suitable antibodies are not available or are insufficiently selective to discriminate closely related protein isoforms. We validated RNA ISH as specificity control for IHC and as a potential alternative method for selecting patients for treatment with MET inhibitors. MET, the HGF receptor, is encoded by the MET proto-oncogene that may be activated by mutation or amplification. MET expression and activity were tested in a panel of control cell lines. MET could be detected in formalin fixed paraffin, embedded (FFPE) samples by IHC and RNA ISH, and this was confirmed by sandwich immunoassays of fresh frozen samples. Gastric cancer cell lines with high MET expression and phosphorylation of tyrosine-1349 respond to the MET inhibitor, BAY-853474. High expression and phosphorylation of MET is a predictive biomarker for response to MET inhibitors. We then analyzed MET expression and activity in a matched set of FFPE vs. fresh frozen tumor samples consisting of 20 cases of gastric cancer. Two of 20 clinical samples investigated exhibited high MET expression with RNA ISH and IHC. Both cases were shown by sandwich immunoassays to exhibits strong functional activity. Expression levels and functional activity in these two cases were in a range that predicted response to treatment. Our findings indicate that owing to its high selectivity, RNA ISH can be used to confirm findings obtained by IHC and potentially may replace IHC for certain targets if no suitable antibodies are available. RNA ISH is a valid platform for testing predictive biomarkers for patient selection.

Developing New Treatments for Heart Failure: Focus on the Heart

Compared with heart failure (HF) care 20 to 30 years ago, there has been tremendous advancement in therapy for ambulatory HF with reduced ejection fraction with the use of agents that block maladaptive neurohormonal pathways. However, during the past decade, with few notable exceptions, the frequency of successful drug development programs has fallen as most novel therapies have failed to offer incremental benefit or raised safety concerns (ie, hypotension). Moreover, no therapy has been approved specifically for HF with preserved ejection fraction or for worsening chronic HF (including acutely decompensated HF). Across the spectrum of HF, preliminary results from many phase II trials have been promising but are frequently followed by unsuccessful phase III studies, highlighting a disconnect in the translational process between basic science discovery, early drug development, and definitive clinical testing in pivotal trials. A major unmet need in HF drug development is the ability to identify homogeneous subsets of patients whose underlying disease is driven by a specific mechanism that can be targeted using a new therapeutic agent. Drug development strategies should increasingly consider therapies that facilitate reverse remodeling by directly targeting the heart itself rather than strictly focusing on agents that unload the heart or target systemic neurohormones. Advancements in cardiac imaging may allow for more focused and direct assessment of drug effects on the heart early in the drug development process. To better understand and address the array of challenges facing current HF drug development, so that future efforts may have a better chance for success, the Food and Drug Administration facilitated a meeting on February 17, 2015, which was attended by clinicians, researchers, regulators, and industry representatives. The following discussion summarizes the key takeaway dialogue from this meeting.

Abstract 3792: Improved isolation and detection of circulating tumor cells of pancreatic cancer patients with characterization by mutational analysis

Introduction: Isolation of circulating tumor cells based on cell surface markers is often hindered by epithelial to mesenchymal transition with loss of epithelial antigens. Low numbers of CTCs and fewer cases of CTC positive pancreatic cancer compared to other cancers (e.g. breast cancer) lead to the assumption that pancreatic tumors do not release CTCs as frequently or that the pancreatic CTCs lack EpCAM expression. Isolation of CTCs based on their size is independent of EMT-like phenotypical changes. We therefore compared a filtration-based isolation method with an EpCAM-based isolation method. We optimized CTC detection by using a highly sensitive anti-cytokeratin antibody panel for the detection of cancer cells with moderate cytokeratin expression. In order to use isolated CTCs as liquid biopsy for tumor characterization and treatment selection, downstream analysis is necessary. We here show the feasibility of mutational analysis of isolated CTCs by castPCR.

Methods: EpCAM high, medium and low cells were enriched and isolated by an EpCAM-based immunomagnetic procedure (IsoFlux) and a filtration device (Siemens) to determine recovery rates of both methods. Isolated cells were detected by an improved immunofluorescent staining with an anti-Cytokeratins, anti-EpCAM and anti-PBMC panel and characterized by competitive allele-specific TaqMan PCR (castPCR) for KRAS mutations.

Results: Cytokeratin expression is crucial for detection of CTCs in a high background of blood cells. Improvement of the staining protocol helps to increase the sensitivity of detection. The filtration based approach is superior to the surface antigen-based isolation. With the size-dependent method we obtained a recovery rate of 52 % even for EpCAM-low cells compared to only 1 % based on the immune-affinity purification. Cells isolated by filtration can be characterized for expression of therapeutic targets by immunostaining. The utility of the size dependent platform for subsequent functional characterization of the CTCs was also demonstrated by detection of k-ras mutations in single isolated CTCs by castPCR.

Conclusion: For CTCs undergoing EMT, filtration yields higher recovery compared to the standard surface antigen (EpCAM)-based methods. Isolation by filtration also allows for mutational analysis which can be used to confirm the identity of the isolated cell as CTC. In addition, mutational analysis of CTCs can be used to guide the treatment of patients. Use of liquid biopsies for treatment selection will facilitate truly personalized medicine.

Citation Format: Oliver von Ahsen, Nora Brychta, Thomas Krahn. Improved isolation and detection of circulating tumor cells of pancreatic cancer patients with characterization by mutational analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3792. doi:10.1158/1538-7445.AM2017-3792

Abstract 3786: Multicenter evaluation of technology platforms for the enumeration of circulating tumor cells

Metastasis represents the deadliest feature of cancer, which is fueled by circulating tumor cells (CTCs) being released into the bloodstream from the primary tumor. In addition to the clinical value of CTC enumeration for metastatic risk assessment, CTCs are considered to be a minimally invasive source for studying the molecular and genetic features of the disease as well as response to anticancer therapy. Given the molecular heterogeneity of CTCs, which includes loss of epithelial surface marker expression, several microfluidic and filtration technology platforms were developed to overcome the limitations of surface marker dependent CTC enrichment. Here we describe the efforts of the Innovative Medicines Initiative (IMI) consortium CANCER-ID (www.cancer-id.eu), which represents a joint undertaking of experts from academia and pharmaceutical industry, in generating comparative data using different CTC enrichment platforms in a multicenter ring trial.

To address clinically relevant subtypes of Non-Small Cell Lung Cancer (NSCLC), different NSCLC cell lines were profiled for genetic aberrations (mutations and copy number aberrations), expression of epithelial markers (epithelial cell adhesion molecule (EPCAM) and cytokeratins) as well as cell size. Cell lines were selected to generate spike-in samples using blood of healthy volunteers with informed consent in a centralized way. Analysis was performed by at least three CANCER-ID partners using different CTC enrichment technologies including the Siemens filtration device, the Parsortix PR1, VyCap filtration and the CellSearch system.

To ensure quality and comparability of results, CANCER-ID partners established standard operation procedures (SOPs) for pre-analytic sample handling including sample fixation, storage and shipment. Special attention was paid on the development of SOPs for the actual CTC enrichment procedure and the integration of downstream applications including single cell isolation by DEPArray™ followed by Ampli1™ WGA and molecular and genetic characterization of isolated cells. Epitope-independent enrichment by filtration or microfluidic devices was evaluated by using NSCLC cells with substantially different cell size. In addition, comparative data on spike-in samples was generated using the EPCAM-expression dependent CellSearch system, which failed to detect EPCAM-negative tumor cells.

In conclusion, the evaluation of different CTC enrichment technologies and the integration of workflows for downstream analysis of single cells blaze the trail for the next phase of IMI’s CANCER-ID, which includes the analysis of real-life NSCLC patient material.

This work is supported by IMI JU & EFPIA (grant no. 115749).

Citation Format: Sebastian Bender, Merlin V. Lütke-Eversloh, Rui P. Neves, NNikolas H. Stoecklein, Leon W. Terstappen, Barbara Baggiani, Martin H. Neumann, Thomas Krahn, Klaus Pantel, Thomas Schlange, Leonie L. Zeune. Multicenter evaluation of technology platforms for the enumeration of circulating tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3786. doi:10.1158/1538-7445.AM2017-3786

Reliability of peripheral arterial tonometry in patients with heart failure, diabetic nephropathy and arterial hypertension

Endothelial dysfunction plays a major role in cardiovascular diseases and pulse amplitude tonometry (PAT) offers a non-invasive way to assess endothelial dysfunction. However, data about the reliability of PAT in cardiovascular patient populations are scarce. Thus, we evaluated the test-retest reliability of PAT using the natural logarithmic transformed reactive hyperaemia index (LnRHI). Our cohort consisted of 91 patients (mean age: 65±9.7 years, 32% female), who were divided into four groups: those with heart failure with preserved ejection fraction (HFpEF) ( n=25), heart failure with reduced ejection fraction (HFrEF) ( n=22), diabetic nephropathy ( n=21), and arterial hypertension ( n=23). All subjects underwent two separate PAT measurements at a median interval of 7 days (range 4-14 days). LnRHI derived by PAT showed good reliability in subjects with diabetic nephropathy (intra-class correlation (ICC) = 0.863) and satisfactory reliability in patients with both HFpEF (ICC = 0.557) and HFrEF (ICC = 0.576). However, in subjects with arterial hypertension, reliability was poor (ICC = 0.125). We demonstrated that PAT is a reliable technique to assess endothelial dysfunction in adults with diabetic nephropathy, HFpEF or HFrEF. However, in subjects with arterial hypertension, we did not find sufficient reliability, which can possibly be attributed to variations in heart rate and the respective time of the assessments. Clinical Trial Registration Identifier: NCT02299960.

Detection of KRAS Mutations in Circulating Tumor DNA by Digital PCR in Early Stages of Pancreatic Cancer

BACKGROUND

Since surgical removal remains the only cure for pancreatic cancer, early detection is of utmost importance. Circulating biomarkers have potential as diagnostic tool for pancreatic cancer, which typically causes clinical symptoms only in advanced stage. Because of their high prevalence in pancreatic cancer, KRAS proto-oncogene, GTPase [KRAS (previous name: Kirsten rat sarcoma viral oncogene homolog)] mutations may be used to identify tumor-derived circulating plasma DNA. Here we tested the diagnostic sensitivity of chip based digital PCR for the detection of KRAS mutations in circulating tumor DNA (ctDNA) in early stage pancreatic cancer.

METHODS

We analyzed matched plasma (2 mL) and tumor samples from 50 patients with pancreatic cancer. Early stages (I and II) were predominant (41/50) in this cohort. DNA was extracted from tumor and plasma samples and tested for the common codon 12 mutations G12D, G12V, and G12C by chip-based digital PCR.

RESULTS

We identified KRAS mutations in 72% of the tumors. 44% of the tumors were positive for G12D, 20% for G12V, and 10% for G12C. One tumor was positive for G12D and G12V. Analysis of the mutations in matched plasma samples revealed detection rates of 36% for G12D, 50% for G12V, and 0% for G12C. The detection appeared to be correlated with total number of tumor cells in the primary tumor. No KRAS mutations were detected in 20 samples of healthy control plasma.

CONCLUSIONS

Our results support further evaluation of tumor specific mutations as early diagnostic biomarkers using plasma samples as liquid biopsy.

Abstract 513: Standardization of technologies for CTC, ctDNA and miRNA enrichment, isolation and analysis for liquid biopsies during the first year of IMI's CANCER-ID

Within the European Innovative Medicines Initiative (IMI) consortium CANCER-ID (www.cancer-id.eu), scientists at academic, clinical and industrial sites across Europe and in the US joined forces to evaluate innovative technologies in the field of liquid cancer biopsies. This project aims at implementing standard operating procedures (SOPs) for pre-analytical sample handling, enrichment, isolation and analysis of Circulating Tumor Cells (CTCs), circulating free tumor DNA (ctDNA) and microRNAs (miRNAs) as novel blood-based biomarkers, with a focus on Non-Small Cell Lung Cancer (NSCLC) and HER2-treatment refractory breast cancer. In order to determine sensitivity and specificity of different technologies for CTC isolation and analysis (e.g. detection of mutations, amplifications, protein phosphorylation), complex samples comprising a mixture of NSCLC or breast cancer cell lines spiked in healthy donor blood were distributed to different CANCER-ID partner sites. These cell lines have been selected based on their molecular/genetic properties to reflect clinically relevant subtypes of the disease and have been further characterized in terms of cell-surface marker expression and cell size distribution. The use of complex spiked samples better models the heterogeneity of real-life patient material. Furthermore, healthy donor and patient derived plasma samples are investigated using different technology platforms to validate tumor-specific miRNA or ctDNA profiles that might characterize molecular tumor subtypes. To this end, differences in exosome-derived versus free circulating miRNAs are of special interest. As for CTCs the development of ctDNA and miRNA standards that can be used to compare and validate different technologies are in the focus of this effort. In summary, our results pave the way for the next phase of CANCER-ID, which includes the analysis of cancer patient samples in clinical studies using different technologies and thereby advance the concept of liquid biopsy particularly in indications in which conventional tissue biopsies are difficult to obtain.

Citation Format: Thomas Schlange, Nikolas Stoecklein, Rui P. Neves, Sabrina Pleier, Sebastian Bender, Nora Brychta, Merlin V. Luetke-Eversloh, Kiki Andree, Leon Terstappen, Thomas Krahn, Thomas Krahn. Standardization of technologies for CTC, ctDNA and miRNA enrichment, isolation and analysis for liquid biopsies during the first year of IMI's CANCER-ID. [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 513.

Abstract 4933: In Situ analysis of FGFR2 RNA and comparison with FGFR2 gene copy number by dual-color in situ hybridization in a large cohort of gastric cancer patients

Gastric cancer is the 3rd most common cause of cancer-related mortality worldwide, thus new treatment options are urgently needed. In gastric cancer, over-expression of the tumor-promoting tyrosine kinase receptor fibroblast growth factor receptor 2 (FGFR2) has been described, representing a potential therapeutic target. FGFR2 expression in gastric cancer has been reported to be heterogeneous. Most methods for detection of RNA in FFPE (formalin fixed paraffin embedded) do not provide spatial resolution for assessment of tumor heterogeneity. Here we used a novel RNA in situ technique called RNAscope. The technology allows visual investigation of FGFR2 transcription on FFPE slides. Samples from 1036 gastric adenocarcinoma patients who underwent surgery in National Cancer Center Hospital East (Chiba, Japan) were assembled in tissue micro-arrays and analyzed by RNAscope. A total of 578 samples were also analyzed by DISH to determine gene amplification. Using these tissue based methods we were able to assess the localization and heterogeneity of both FGFR2 gene amplification and RNA expression. Strong FGFR2 gene amplification (FGFR2:CEN10 &gt;10) was detected in 2% of 578 samples. Moderate FGFR2 gene amplification (FGFR2:CEN10 between 2 and 10) was seen in 8% of the samples. High FGFR2 RNA expression (score 4+) was seen in 4% of 718 evaluable samples. Gene amplification and RNA expression were closely correlated. All samples with dense clusters of score 4+ RNA showed FGFR2:CEN10 ratios &gt;10. The identical tumor areas showed high gene amplification and RNA expression. FGFR2 RNA and gene amplification was highly heterogeneous in the tissue. Only 0.4% of the samples showed homogeneous FGFR2 expression in &gt;80% of the tumor cells. High RNA expression intensity was associated with a more homogeneous expression pattern compared to moderate FGFR2 expression. In early stage I/II gastric cancer samples with score 4+ RNA expression are mostly of the differentiated type. RNA score 4+ patients of grade III/IV gastric cancer were mostly of undifferentiated histology. In a subset of 195 samples with available data cMet IHC 3+ and Her2 positivity status were not mutually exclusive with regards to FGFR2 RNA Score 4+ expression. In a multivariant analysis FGFR2 RNA expression was associated with patient outcome. Gastric cancer patients with score 4+ RNA expression had a shorter progression free survival compared to patients with score 0-3. Interestingly, there was a trend for patients with homogeneous score 3+ RNA expression, but not heterogeneous score 3+ expression, to show shorter PFS and OS suggesting that patients with high intensity or homogeneous FGFR2 RNA expression may define a subgroup of patients with gastric cancer. Patients with homogenous or strong focal FGFR2 expression might therefore be candidates for FGFR2 directed therapies in gastric cancer.

Citation Format: Yasutoshi Kuboki, Christoph A. Schatz, Sabine Jabusch, Karl Koechert, Janine Feng, Sabine Wittemer-Rump, Karl Ziegelbauer, Thomas Krahn, Akiko Nagatsuma, Atsushi Ochiai. In Situ analysis of FGFR2 RNA and comparison with FGFR2 gene copy number by dual-color in situ hybridization in a large cohort of gastric cancer patients. [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 4933.

Abstract 413: Validation of an antibody independent tool for patient selection: RNA in situ hybridization detects Met expression levels predictive for response to Met inhibition by Bay 853474

This study was performed in order to validate RNA in situ hybridization (RNA ISH) as tool for patient selection. Met expression was analyzed in a matched sample set of FFPE versus fresh frozen tumor samples comprising 20 cases of gastric cancer. Classical immunohistochemistry using the antibody SP44 and RNA ISH (RNAscope by ACD) were used to detect c-met expression in FFPE material. The results were confirmed by sandwich-immunoassays on Met and its phosphorylation on tyrosine 1349 (MSD) as well as mass spectrometry. The level of functional relevance was determined by testing a set of cell lines comprising some with genomic amplification of the met gene as well as some non-amplified lines showing different expression levels. Among gastric cancer cell lines only those with met amplification respond to treatment with the small molecule Met inhibitor Bay 853474. The cell line result generates a responder hypothesis that can be used to define a cutoff for clinical samples. 2 of the 20 investigated clinical samples were shown to have high level Met expression by RNA ISH and IHC that could be confirmed by sandwich-immunoassays also showing high level of functional activity by phosphotyrosine 1349. Met expression in these cases was also confirmed by mass spectrometry. Expression levels and functional activity in these 2 cases were in the range that predicts response to treatment as established with gastric cancer cell lines. Determination of predictive biomarkers by immunohistochemistry can be limited due to lack of high quality antibodies of sufficient specificity. Due to its high specificity, RNA in situ hybridization is a technique that can be used to confirm the findings obtained by immunohistochemistry and may potentially even replace immunohistochemistry it if no suitable antibodies are available or not specific enough e.g. to discriminate between closely related protein isoforms. We show the biological relevance of RNA in situ hybridization on FFPE samples by correlation with immunohistochemistry, ELISA based approaches and mass spectrometry. RNA ISH is shown to be specific and sensitive enough to identify cases of functionally relevant MET overexpression levels in gastric cancers and can be used to select patients for treatment.

Citation Format: Oliver von Ahsen, Thomas Krahn, Christoph Schatz. Validation of an antibody independent tool for patient selection: RNA in situ hybridization detects Met expression levels predictive for response to Met inhibition by Bay 853474. [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 413.

Potential role for interferon-γ release assays in tuberculosis screening in a remote Canadian community: a case series

BACKGROUND

Current Canadian guidelines suggest that neonatal Bacille Calmette-Guérin (BCG) vaccination does not result in false-positive tuberculosis (TB) skin tests, despite a growing body of evidence that interferon-γ release assays may be a more specific alternative in identifying latent tuberculosis infections in vaccinated populations. We set out to evaluate the relationship between TB skin tests and interferon-γ release assays in patients who previously received neonatal BCG vaccine.

METHODS

All children with a positive skin test at age 14 years in a remote community north of Sioux Lookout, Ontario, were considered for interferon-γ release assay testing.

RESULTS

Of the 11 children who underwent routine screening at 14 years of age for latent TB infection, 7 had a positive TB skin test (≥ 10 mm). All 7 of these children had received the BCG vaccine as newborns and all had a negative TB skin test during their routine screening at 4 years of age. No potential exposure to active TB could be identified. Chest radiographs were normal, and none of the children had symptoms suggestive of active TB. The 7 children underwent interferon-γ release assay testing using QuantiFERON Gold. All 7 tests were negative.

INTERPRETATION

With the addition of interferon-γ release assays to routine skin test screening, we provide evidence that neonatal BCG vaccination may contribute to a false-positive skin test in youth at 14 years of age. Consideration should be given to the possibility that neonatal BCG may contribute to false-positive TB skin tests.

Enumeration and Molecular Characterization of Tumor Cells in Lung Cancer Patients Using a Novel In Vivo Device for Capturing Circulating Tumor Cells

PURPOSE

The use of circulating tumor cells (CTC) as "liquid biopsy" is limited by the very low yield of CTCs available for subsequent analyses. Most in vitro approaches rely on small sample volumes (5-10 mL).

EXPERIMENTAL DESIGN

Here, we used a novel approach, the GILUPI CellCollector, which enables an in vivo isolation of CTCs from peripheral blood. In total, 50 lung cancer patients were screened in two subsequent device applications before and after therapy (n = 185 applications).

RESULTS

By in vivo isolation, 58% (108/185) of the patients were positive for ≥1 CTC (median, 5 CTCs; range, 1-56 cells) as compared with 27% (23/84; range, 1-300 cells) using the FDA-cleared CellSearch system. Furthermore, we could show that treatment response during therapy was associated with significant decreases in CTC counts (P = 0.001). By dPCR, mutations in the KRAS and EGFR genes relevant for treatment decisions could be detected in CTCs captured by in vivo isolation and confirmed in the primary tumors of the same patients.

CONCLUSIONS

In vivo isolation of CTCs overcomes blood volume limitations of other approaches, which might help to implement CTC-based "liquid biopsies" into clinical decision making. Clin Cancer Res; 22(9); 2197-206. ©2015 AACR.

Abstract 1583: Circulating tumor cells isolated from non-small cell lung cancer patients using the in vivo CellCollector Technology

Access to tumor tissue is often limiting and archival samples may not be reflective of the current disease. Alternative approaches using liquid biopsies are being explored to support personalized treatment of cancer patients. Circulating tumor cells (CTCs) detached from primary tumors or metastases into the blood may reflect the current molecular tumor profile providing the opportunity to monitor molecular changes in the tumor. As CTCs are rare cells in the bloodstream and most in vitro approaches for capturing CTCs are based on small samples volumes (5 - 10 ml), accurate and reliable quantification of CTCs is difficult to achieve. We report on a comprehensive clinical study using a novel CellCollectorTM for in vivo isolation of CTCs.

Eighty four stage I - IIIB non-small cell lung cancer (NSCLC) patients and 7 healthy individuals were screened for CTCs using a CellCollectorTM (Gilupi, Germany) device. Molecular analysis of a patient with known mutation in the KRAS gene (G12D) was performed to confirm the predictive value of CTCs as “liquid biopsy”. CTCs were detected in 65 out of 84 NSCLC patients (77.4%) (median: 13 CTCs; range from 0 - 300). For comparison, using the U.S. Food and Drug Administration-cleared CellSearch® system only fifteen samples (17.8%) in this cohort were positive (median: 0 CTCs; range from 0-300). In all paired samples, the CellCollectorTM detected the same or higher numbers of CTCs. Healthy individuals were devoid of any cells classified as CTC. Investigating the KRAS status on CTCs captured by the CellCollectorTM, we were able to substantiate the G12D mutation that has earlier on been identified in the tissue of the primary lung tumor.Conclusions: The CellCollectorTM is a promising novel device for the in vivo isolation of CTCs and the device effectively isolated CTCs from NSCLC patients of all stages including the non-metastatic setting. The implementation of the CellColletorTM into clinical practice has the potential for early disease detection. Furthermore, this approach allows the molecular characterization of CTCs for possible therapeutic targets and early response to treatment which might be used in the setting of personalized cancer therapies and clinical development.

Citation Format: Thomas Krahn, Lukasz Gasiorowski, Wojciech Dyszkiewicz, Grzegorz Dworacki, Maciej Zabel, Dave S. Hoon, Stefanie Herold, Bjoern Nowack, Johannes Tucholsky, Christian Schumann, Klaus Lücke. Circulating tumor cells isolated from non-small cell lung cancer patients using the in vivo CellCollector Technology. [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 1583. doi:10.1158/1538-7445.AM2015-1583

Abstract 1604: IMI CANCER-ID: Validation of novel blood-based biomarker technologies in clinical settings

The Innovative Medicines Initiative (IMI) was launched in 2008 as a public-private partnership between the European Union and the European Federation of Pharmaceutical Industries and Associations (EFPIA). IMI aims to facilitate the collaboration of healthcare stakeholders such as academic and clinical researchers, pharmaceutical industry and small and medium-sized enterprises (SMEs) in Europe, in order to address key issues in drug development and patient access to innovative medicines.

Tumor heterogeneity and the dynamic changes at the molecular level during disease progression make longitudinal monitoring of malignant disease highly desirable in order to choose the best treatment options and to monitor treatment efficacy. As access to tumor tissue is often the limiting factor and historic samples are not predictive for the current state of the disease, liquid biopsies are explored to support personalized treatment of cancer patients. The CANCER-ID consortium was established in 2014 and aims to validate technologies for blood-based biomarkers such as Circulating Tumor Cells (CTCs), circulating tumor DNA (ctDNA) and microRNAs (miRNAs) to determine the absence/presence of drug targets and to assess the response to treatment. To prove broader applicability and clinical utility of the consortium's technologies and protocols, the validated assays will be deployed in controlled clinical studies (TRACERx, NCT01888601; NVALT17, NTR4410; SPECTAlung, NCT02214134; patients under SoC treatment) in 1) Non-Small Cell Lung Cancer (NSCLC) and 2) anti-Her2-resistant metastatic breast cancer (Her2RMBC). CANCER-ID is a unique network of experts in the fields of tumor biology, biomarker development, clinical sciences and bioinformatics with a total indicative budget of 14 Mio €. The consortium joins forces of 16 academic groups (ten large clinical trial sites), 6 EFPIA companies, 1 multi-national diagnostics company, 5 SMEs with advanced technologies for CTC isolation or for complex data analysis and big data handling, and two non-profit organizations. In order to fully exploit the synergies created by CANCER-ID, regulatory agencies and patient advocacy groups are involved and invited to participate in the IMI project.

Citation Format: Thomas Schlange, Thomas Krahn, Sabrina Pleier, Klaus Pantel, Leon WMM Terstappen, Barbara Baggiani. IMI CANCER-ID: Validation of novel blood-based biomarker technologies in clinical settings. [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 1604. doi:10.1158/1538-7445.AM2015-1604

Abstract 931: Enrichment and characterization of propagating circulating tumor cells from late stage prostate and pancreatic cancer patients

Capturing cells shed by a tumor into the bloodstream represents an opportunity to study the properties of these cells for biomarker discovery in support of drug development and personalized therapy. Enrichment and expansion of circulating tumor cells (CTCs) in culture enables molecular characterization not readily available for rare cells. We report on a primary cell culture platform to enrich and expand rare circulating cells from the blood of patients with metastatic castration resistant prostate cancer and pancreatic ductal adenocarcinoma. The approach relies on tumor cell enrichment via cell-binding substrates comprised of a collagen-based hydrogel for CTC capture, and hypoxic culturing conditions to maintain and propagate subset of these cells with tumor-initiating potential.

Here, we demonstrate the successful identification and expansion of rare circulating tumor cells from peripheral blood and leukapheresed blood samples from prostate and pancreatic cancer patients, respectively. Upon successful culture of samples for a period of 5 to10 days after plating, immunofluorescence imaging was performed. Morphologically distinct CTC colonies positive for PSMA, EpCAM and cytokeratin staining were observed, with individual colonies ranging from approximately 50 to 1000 in cell number. Interestingly, colonies consistently revealed white blood cell contaminants (T-cells and dendritic cells) that did not appear to perturb colony growth.

Targeted DNA sequencing was performed on pancreatic CTC colonies from six patients using a genetic panel covering 237 genes. We achieved 100-200X coverage for each patient sample and present a preliminary genetic characterization of their CTCs in culture. Our results show unique genetic signatures indicative of aggressive forms of pancreatic ductal adenocarcinoma based on SNP/INDEL detection, CNV analysis and gene fusion predictions. In summary, cultured CTCs had 20-30X more variants than corresponding white blood cell controls, with mutations observed in MLL2, ARID1A, BRAF, KRAS and BRCA2. CNV analysis and gene fusion predictions revealed previously unreported biomarker candidates.

In conclusion, we show that viable CTCs are amenable to ex vivo culture, providing both functional and molecular insights into a sub-population of CTCs with propagating potential. The presence of T-cells and dendritic cells on CTC colonies warrants further investigation, and may provide unique insights into immune-tumor interactions. The culturing platform is currently being evaluated as a research tool for biomarker discovery and as a clinical tool for disease monitoring and treatment decision-making.

Citation Format: James I. Lim, Charles J. Ryan, Thomas Krahn, Nikolas H. Stoecklein, Johannes Fischer, Bruce Adams. Enrichment and characterization of propagating circulating tumor cells from late stage prostate and pancreatic cancer patients. [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 931. doi:10.1158/1538-7445.AM2015-931

Impact of Biomarkers on Personalized Medicine

The field of personalized medicine that involves the use of measuring biomarkers in clinical samples is an area of high interest and one that has tremendous impact on drug development. With the emergence of more sensitive and specific technologies that are now able to be run in clinical settings and the ability to accurately measure biomarkers, there is a need to understand how biomarkers are defined, how they are used in clinical trials, and most importantly how they are used in conjunction with drug treatment. Biomarker approaches have entered into early clinical trials and are increasingly being used to develop new diagnostics that help to differentiate or stratify the likely outcomes of therapeutic intervention. Tremendous efforts have been made to date to discover novel biomarkers for use in clinical practice. Still, the number of markers that make it into clinical practice is rather low. In the next following chapters, we will explain the various classifications of biomarkers, how they are applied, measured, and used in personalized medicine specifically focusing on how they are used in de-risking the 10 plus years drug development process and lastly how they are validated and transformed into companion diagnostic assays.

AmgRS-mediated envelope stress-inducible expression of the mexXY multidrug efflux operon of Pseudomonas aeruginosa

AmgRS is an envelope stress-responsive two-component system and aminoglycoside resistance determinant in Pseudomonas aeruginosa that is proposed to protect cells from membrane damage caused by aminoglycoside-generated mistranslated polypeptides. Consistent with this, a ΔamgR strain showed increased aminoglycoside-promoted membrane damage, damage that was largely absent in AmgRS-activated amgS-mutant strains. Intriguingly, one such mutation, V121G, while providing for enhanced resistance to aminoglycosides, rendered P. aeruginosa susceptible to several ribosome-targeting nonaminoglycoside antimicrobials that are inducers and presumed substrates of the MexXY-OprM multidrug efflux system. Surprisingly, the amgSV 121G mutation increased mexXY expression threefold, suggesting that export of these nonaminoglycosides was compromised in the amgSV 121G mutant. Nonetheless, a link was established between AmgRS activation and mexXY expression and this was confirmed in studies showing that aminoglycoside-promoted mexXY expression is dependent on AmgRS. While nonaminoglycosides also induced mexXY expression, this was not AmgRS-dependent, consistent with these agents not generating mistranslated polypeptides and not activating AmgRS. The aminoglycoside inducibility of mexXY was abrogated in a mutant lacking the AmgRS target genes htpX and PA5528, encoding a presumed cytoplasmic membrane-associated protease and a membrane protein of unknown function, respectively. Thus, aminoglycoside induction of mexXY is a response to membrane damage and activation of the AmgRS two-component system.

Abstract 2836: Development of a companion diagnostic IHC assay for the biomarker-driven selection of C4.4a positive patients

C4.4a (LYPD3), a GPI-anchored cell surface protein, has been identified previously as a cancer- and metastasis-associated cell surface protein. It is expressed in a variety of cancer indications and, particularly, in the squamous cell subtype of non-small cell lung cancer (NSCLC) and head and neck cancer. Targeting C4.4a with a specific antibody-drug conjugate showed a potent and selective antitumor activity in various human xenograft models and in patient-derived NSCLC tumor models (Willuda J et al., AACR 2014). Since it has been previously shown in vivo that the expression of C4.4a is required for the response to anti-C4.4a treatment, we initiated the development of an IHC assay that might be used to detect C4.4a expression in patient tumor samples. For the development of this companion diagnostic IHC assay, a novel monoclonal rabbit anti-C4.4a antibody was generated. Since C4.4a is post-transcriptionally modified by shedding, we aimed to identify an antibody that binds to a similar epitope as the therapeutic C4.4a antibody. The immunizations of rabbits with specific peptide sequences of C4.4a and with the full length C4.4a recombinant protein produced several antibody candidates. Those antibody candidates were characterized in regard to their staining characteristics, domain binding, and specificity for C4.4a. Furthermore, the staining pattern of the antibody candidates and the therapeutic C4.4a antibody were compared side by side to ensure that stainings using the newly generated antibodies are predictive for anti-C4.4a treatment. The most promising antibodies were selected to set up and optimize an IHC assay on the Ventana staining platform. In summary, we developed a companion diagnostic IHC assay that might be used to detect C4.4a expression in patient tumor samples.

Citation Format: Claudia Schneider, Joseph Couto, Yifei Zhu, Zhiming Liao, Robert Pytela, Alton Hiscox, Sabine Wittemer-Rump, Ulf Forssmann, Lars Linden, Joerg Willuda, Daniel Forler, Matthew Nelson, Ricarda Finnern, Thomas Krahn, Khusru Asadullah. Development of a companion diagnostic IHC assay for the biomarker-driven selection of C4.4a positive patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2836. doi:10.1158/1538-7445.AM2014-2836