Bayesian heterogeneity in a meta-analysis with two studies and binary data

The meta-analysis of two trials is valuable in many practical situations, such as studies of rare and/or orphan diseases focussed on a single intervention. In this context, additional concerns, like small sample size and/or heterogeneity in the results obtained, might make standard frequentist and Bayesian techniques inappropriate. In a meta-analysis, moreover, the presence of between-sample heterogeneity adds model uncertainty, which must be taken into consideration when drawing inferences. We suggest that the most appropriate way to measure this heterogeneity is by clustering the samples and then determining the posterior probability of the cluster models. The meta-inference is obtained as a mixture of all the meta-inferences for the cluster models, where the mixing distribution is the posterior model probability. We present a simple two-component form of Bayesian model averaging that is unaffected by characteristics such as small study size or zero-cell counts, and which is capable of incorporating uncertainties into the estimation process. Illustrative examples are given and analysed, using real sparse binomial data.

A33 ENDOSCOPIC ULTRASOUND-GUIDED GASTROJEJUNOSTOMY VERSUS SURGICAL GASTROJEJUNOSTOMY AND ENTERAL STENTING FOR THE TREATMENT OF MALIGNANT GASTRIC OUTLET OBSTRUCTION: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background

Gastric outlet obstruction (GOO), often encountered in advanced malignancy, is associated with debilitating symptoms and decreased quality of life. Traditional management of this condition has been surgical gastrojejunostomy (SGJ) or enteral stenting (ES). While SGJ is highly effective, it is invasive and associated with high rates of morbidity. ES provides a less invasive approach with a lower risk of adverse events; however, it is associated with a significant risk of stent dysfunction with increased need for reintervention. Endoscopic ultrasound-guided gastrojejunostomy (EUS-GJ) is a novel modality in the management of GOO that aims to endoscopically bypass the obstruction with a lumen-apposing metal stent, with early studies suggesting good effectiveness and safety outcomes; but the data are limited.

Aims

To perform a systematic review and meta-analysis comparing the clinical outcomes of EUS-GJ to more traditional treatments of malignant GOO.

Methods

The study protocol was prospectively registered with the PROSPERO international database. The literature was systematically searched using MEDLINE, EMBASE and Web of Knowledge databases from inception through May 2021. Studies comparing EUS-GJ to ES or SGJ in patients with malignant GOO were included. Meta-analysis was performed with results reported as odds ratios (ORs) with 95% confidence intervals (CIs) using random effects models. The two primary outcomes of interest were clinical success without GOO recurrence and adverse events. Secondary outcome was technical success.

Results

Ten studies with a total of 1016 patients were included. EUS-GJ was associated with higher clinical success without GOO recurrence compared to SGJ or ES [OR: 2.19, 95% CI: 1.18–4.09, heterogeneity: P = 0.10; I² = 59%]. Subgroup analysis showed higher clinical success without GOO recurrence compared to ES [OR: 5.31, 95% CI: 3.07–9.17], but no significant difference compared to SGJ [OR: 1.69, 95% CI: 0.76–3.72]. EUS-GJ was associated with fewer adverse events compared to SGJ and ES [OR: 0.28, 95% CI: 0.14–0.55] and compared to SGJ alone [OR: 0.20, 95% CI: 0.10–0.37], but no difference was noted when compared to ES alone [OR: 0.53, 95% CI: 0.15–1.87]. EUS-GJ was associated with decreased technical success compared to SGJ and ES [OR: 0.26, 95% CI: 0.09 – 0.75] and SGJ alone [OR: 0.14, 95% CI: 0.04–0.48]; however, there was no difference when compared to ES alone [OR: 0.43, 95% CI: 0.05–3.44].

Conclusions

EUS-GJ provides a robust bypass with lower risk of recurrent obstruction compared to ES and fewer adverse events compared to SGJ. High quality prospective studies are needed to further characterize the role of EUS-GJ in the management of malignant GOO.

Funding Agencies

None

A27 COMPARATIVE EVALUATION OF THE ABC SCORE TO OTHER RISK STRATIFICATION SCALES IN MANAGING HIGH-RISK PATIENTS PRESENTING WITH ACUTE UPPER GASTROINTESTINAL BLEEDING

Background

The ABC risk score identifies patients at high-risk of mortality in acute lower and upper gastro-intestinal bleeding (UGIB).

Aims

We aimed to externally validate the ABC score, while comparing it to other prognostication scales when assessing UGIB patients at high-risk of negative outcomes prior to endoscopy.

Methods

UGIB patients from a national Canadian registry (REASON) were studied, with mortality prediction as primary outcome. Secondary endpoints included prognostication of rebleeding, intensive care unit (ICU) admission, ICU and hospitalization lengths of stay (LOS), and a previously proposed composite outcome measure. Univariable and areas under the Receiver Operating Characteristic Curve (AUROC) analyses compared discriminatory abilities of the ABC score to the AIMS65, Glasgow Blatchford (GBS) and clinical Rockall Scores.

Results

The REASON registry included 2020 patients (89.4% nonvariceal; mean age [± SD] 66.3±16.4 years; 38.4% female). Overall mortality, rebleeding, ICU admission, transfusion and composite score rates were 9.9%, 11.4%, 21.1%, 69.0%, and 67.3% respectively. ICU and hospitalization LOS were 5.4 ± 9.3 days and 9.1 ± 11.5 days, respectively. The ABC score displayed superior 30-day mortality prediction (0.78 (0.73; 0.83)) compared to GBS (0.69 (0.63; 0.75) or clinical Rockall (0.64 (0.58; 0.70) but not AIMS65 (0.73 (0.67; 0.79)). Although most scales significantly prognosticated secondary outcomes in univariable analysis except for ICU LOS, discriminatory abilities on AUROC analyses were poor.

Conclusions

ABC and AIMS65 display similar good prediction of mortality. Clinical usefulness in prognosticating secondary outcomes was modest for all scales, limiting their adoptions when informing early management of high-risk UGIB patients.

Funding Agencies

International Scientific Partnership Program ISPP at King Saud University for funding this research work through ISPP-21–156

A94 PERI-PROCEDURAL MANAGEMENT OF PATIENTS RECEIVING A DIRECT ORAL ANTICOAGULANT UNDERGOING A DIGESTIVE ENDOSCOPY

Background

The peri-procedural management of patients on a direct oral anticoagulant (DOAC) requiring an elective digestive (GI) endoscopic procedure remains uncertain.

Aims

To investigate the safety of a standardized peri-procedural DOAC management strategy.

Methods

The Perioperative Anticoagulation Use for Surgery Evaluation (PAUSE) cohort study was conducted at 23 clinical centers in North America and Europe. Participants (n=3007) all had atrial fibrillation (AF), were >18 years old, long-term users of Apixaban, Rivaroxaban, or Dabigatran, and scheduled for an elective procedure or surgery; all could adhere to the DOAC interruption protocol. This analysis focuses on the 579 patients undergoing a digestive endoscopic procedure. The DOAC interruption (1–2 days pre-endoscopy) and resumption (1–3 days post-endoscopy) strategy is based on the DOAC molecule, patient renal function, with most GI procedures considered at low-risk for bleeding. Follow-up occurred at 30 days. Outcomes included GI bleeding and thromboembolic events (ischemic stroke, transient ischemic attack, myocardial infarction, systemic embolism, deep vein thrombosis, and pulmonary embolism) and mortality.

Results

Of the 556 patients (72.5 +8.6 yrs; 37.4 % female), 38.9%) were on Apixaban, 36.9% on Rivaroxaban, and 24.3% on Dabigatran; 10.1% were on anti-platelet therapy. The overall CHADS score was 1.7 +1.0. Overall, 525 patients were categorized as having a low risk for bleeding, and 31 were at high-risk. DOAC were stopped 2.0 +0.5 days pre-procedure and restarted 1.9 +1.5 days post-procedure. Overall rates were: all bleeding 4.4% (2.9–6.4), GI bleeding 2.5% (1.4–4.2%), while 0.7% (0.3–1.8%) experienced a thromboembolic event. Additional results are listed in Table 1.

Conclusions

Patients with AF undergoing a standardized DOAC therapy interruption management protocol for elective digestive endoscopy experienced low rates of major bleeding and arterial thromboembolism.

All results reported as % and 95% CI * outcomes were missing for 4 patients that had the procedure

Funding Agencies

None

A134 A MULTI-CENTRE RANDOMIZED CONTROLLED TRIAL TO COMPARE TWO BOWEL CLEANSING REGIMENS AFTER A COLONOSCOPY WITH INADEQUATE BOWEL PREPARATION

Aims

Failed bowel preparation is common during colonoscopy, yet the optimal purgative regimen to use for the next attempt is unknown. The objective of this study was to compare the efficacy, tolerability, and safety of two regimens at supratherapeutic doses for use after failed bowel preparation.

Methods

A multi-centre phase III endoscopist blinded randomized controlled trial (NCT02976805) was conducted in patients who failed bowel preparation, using the US Multi-Society Task Force (USMSTF) definition of inability to exclude polyps >5 mm in size and requiring a shortened interval to next colonoscopy. Regimen A consisted of 15 mg of bisacodyl and 2 + 2 L of split dose polyethylene glycol electrolyte solution (PEG) and Regimen B consisted of 15 mg of bisacodyl and 4 + 2 L of split dose PEG. The primary outcome was adequate bowel preparation, defined as a Boston Bowel Preparation Scale (BBPS) total score ≥ 6 with all segment scores ≥ 2. Secondary outcomes were adequate bowel preparation using the USMSTF definition, median BBPS, adenoma detection (ADR), advanced adenoma detection (aADR), sessile serrated polyp detection (SSPDR), and cecal intubation (CIR). Adverse events were assessed at the time of the colonoscopy and 14 days later.

Results

Between February 2017 and December 2019, 250 subjects were screened at four academic centres in Canada, of which 195 were randomized: 96 to Regimen A and 99 to Regimen B. The mean (SD) age was 60.6 (11.4) years, 87 (45.1%) were female, and the median (IQR) total BBPS score at previous failed colonoscopy was 3 (1,4). Regimen B was not superior to Regimen A in achieving adequate bowel preparation using the BBPS definition (87.6% vs. 91.1%, p=0.45) or the USMSTF definition (85.4% vs 91.1%, p=0.24), nor was it superior with respect to the median BBPS score (7 vs 7, p=0.50), mean ADR (31.5% vs 37.8%, p=0.37), aADR (11.2% vs 18.9%, p=0.15), SSPDR (5.6% vs 8.9%, p=0.40) or CIR (92.1% vs 96.7%, p=0.19). Regimen A had a higher adherence rate (88.2% vs. 74.7%, p=0.02) and greater willingness to undergo the bowel preparation again (91.2% vs. 66.2%, p<0.001). The only serious adverse event occurred in a patient randomized to Regimen B who was admitted to hospital for vomiting after colonoscopy.

Conclusions

Split dose 4L PEG with 15mg of bisacodyl is highly efficacious, well tolerated, and can be used for patients who previously failed first line bowel preparations. The additional 2L of PEG in Regimen B did not improve bowel preparation and was not as well tolerated.

Funding Agencies

AMOSO Opportunities Grant, Pharmascence Inc.

A146 EVALUATION OF A COLONOSCOPY REFERRAL FORM IN QUEBEC: WHICH INDICATIONS CARRIES A HIGHER RISK OF ADVANCED NEOPLASIA?

Background

Patients referral for colonoscopy in the province of Quebec are organized through a standardized triage sheet that includes all indications categorized in 5 hierarchal scheduling priorities. In the context of a restricted access to colonoscopy, exacerbated by the COVID-19 pandemic, postponed elective endoscopies lead to potential diagnostic and therapeutic delays in patients with colorectal neoplasia. There is currently an important need to evaluate available tools to improve patients prioritization.

Aims

This study aims to determine CRC and advanced adenomas (AA) rates associated with indications of priority 3 (P3 fig.1). The secondary objective is to regroup and compare indications with higher and lower rate of CRC and AA.

Methods

This retrospective study included all adult patients who underwent a single diagnostic colonoscopy from March 2013 to March 2016 following a single FIT test in a tertiary teaching hospital. A literature review informed the adopted definition of higher-risk of CRC and AA according to P3 colonoscopy indications. These include: Positive FIT test (IN5), hematochezia in ≥ 40 years old patients (IN4), unexplained iron deficiency anemia (IN6) and symptoms suspicious of occult colorectal cancer (IN18). Lower risk P3 indications were defined as: suspicion of IBD (IN3), recent change in bowel habits (IN7), polyp viewed on imaging (IN17), inadequate bowel preparation (IN19), and diverticulitis follow-up (IN20). Higher and lower risk indications findings were analyzed.

Results

In our cohort of 2226 patients, indications for colonoscopy referral according to the standardized form were available for 1806 patients (10 P1, 69 P2, 1056 P3, 56 P4 and 615 P5). In our studied group of P3 indications, the mean age was 62.6±11.3 years, 54.1% were female and 173 (16.4%) patients had a significant finding of CRC or AA (table 1). Patients referred for higher risk indications had a significantly increased rate of CRC and AA (19.3% vs 5.1% p≤ 0.01) compared to patients referred for lower risk indications.

Conclusions

A standardized colonoscopy referral tool may be adapted to improve prioritization of patients at risk of advanced neoplasia. These findings are especially relevant in the context of limited access to colonoscopy like during a pandemic.

Funding Agencies

None

A132 ENDOSCOPIC ULTRASOUND-GUIDED GASTROENTEROSTOMY USING A NOVEL DOUBLE BALLOON DEVICE IN THE MANAGEMENT OF MALIGNANT GASTRIC OUTLET OBSTRUCTION

Background

EUS-gastroenterostomy (EUS-GE) is a novel modality in the management of malignant gastric outlet obstruction (MGOO). It is, however, technically challenging limiting its widespread application. To facilitate EUS-GE, a double balloon catheter has been developed in Japan. While this tool is not available outside of Asia, we have conceived a similar device using a widely available vascular balloon catheter. We aim to determine the clinical efficacy and safety of EUS-GE using this double balloon device (DBD).

Aims

We aim to determine the clinical efficacy and safety of EUS-GE using this double balloon device (DBD).

Methods

This is a single-centre, retrospective study of consecutive patients who underwent DBD assisted EUS-GE for MGOO from January 2019-June 2020 (IRB approved). The DBD consists of two 60 mm vascular balloons (Coda, Cook Medical, USA) fashioned together with the balloons 10 cm apart (Figure 1). It is inserted across the obstruction over a wire to the ligaments of Treitz. Both balloons are then inflated followed by saline and contrast infusion into the occluded small bowel segment to facilitate EUS-guided insertion of a 15 mm cautery assisted lumen apposing metal stent (AxiosTM, Boston Scientific Inc, USA). The primary endpoint is the rate of technical success defined as adequate deployment of the stent. Secondary endpoints include rate of clinical success and adverse events.

Results

A total of 11 patients were included in this study. 45% were female with a mean age of 64.9 ± 8.6 years old. The etiology of MGOO was 73% pancreatic cancer, 9% gastric cancer, 9% duodenal cancer, and 9% metastatic cervical cancer. Procedures were performed under general anesthesia and conscious sedation in 82% and 18%, of patients respectively. The mean procedure time was 64.8 ± 25.8 minutes. Technical and clinical success (intention to treat) was 91%. The only technical failure was due to poor patient tolerance of the procedure under conscious sedation. There was one adverse event (9%) due to stent migration rated as severe. Two patients (18%) required re-intervention for stent obstruction secondary to food impaction associated with non-compliance to a low-residue diet. Following re-enforced instructions, no further obstruction occurred.

All patients started a clear liquid diet within 1 day of the procedure with a mean time to a low residue diet of 3.25 days ± 2.5. The median length of hospital stay following the procedure was 5 days ± 13. The median follow-up time was 84 days (IQR 152).

Conclusions

DBD assisted EUS-GE is clinically effective and safe. This balloon device may greatly facilitate the technical aspect of EUS-GE while potential enhancing its safety and clinical use. Larger studies are needed to validate this approach to EUS-GE.

Funding Agencies

None

A268 PREOPERATIVE EUS-GUIDED FNA IS ASSOCIATED WITH BETTER OVERALL SURVIVAL IN RESECTABLE PANCREATIC CANCER WHEN COMPARED TO UPFRONT SURGERY WITHOUT PREOPERATIVE TISSUE ACQUISITION: A SYSTEMIC REVIEW AND META-ANALYSIS

Background

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is the standard of care in advanced pancreatic cancer. In resectable disease, preoperative EUS-FNA can help to identify benign etiology and other cancers while preventing unnecessary surgery. However, concerns regarding tumor seeding and pancreatitis have led some experts to advocate for upfront surgery without tissue sampling.

Aims

To conduct a systematic review and meta-analysis of the risks and benefits of performing pre-operative EUS-FNA in patients with suspected, resectable pancreatic cancer.

Methods

A literature search was performed up to April 2019 using MEDLINE, EMBASE, and ISI Web of Knowledge databases with terms specified for pancreatic neoplasm and FNA. All fully published adult studies that compared preoperative EUS-FNA to EUS without FNA in resectable pancreatic cancer for short- and long-term outcomes were included. Results were reported as Odds ratios (OR) or weighted mean differences (WMD) with 95% confidence intervals (CI) using a random effects model. Heterogeneity, publication bias and quality of studies were evaluated. Sensitivity analyses were performed. The primary outcome is overall survival. Secondary outcomes include cancer free survival, tumor recurrence and seeding, and post FNA adverse events.

Results

An initial search yielded 2814 citations. Six retrospective studies were included with 1155 patients in the EUS-FNA group vs 2067 patients in the comparator group. Overall survival was reported in three studies (n=2701: 796 EUS-FNA, 1905 non-FNA). Patients with preoperative EUS-FNA had better overall survival compared to the non-FNA group (WMD, 4.40 months [0.02 to 8.78]). In adenocarcinoma patients (2 studies, n=2050), there was no significant difference in overall survival (WMD, 2.94 months [-3.87 to 9.74]). Cancer-free survival did not differ significantly between the two groups (WMD, 2.08 months [-2.22 to 6.38]). Moreover, EUS with FNA was not associated with increased rates of tumor recurrence (OR, 0.55 [0.30–1.02]) or peritoneal carcinomatosis (OR, 0.81 [0.56–1.18]). Post-FNA pancreatitis was rare (1.7%), with all patients treated conservatively. Sensitivity analyses yielded similar findings across the different outcomes tested.

Conclusions

In this meta-analysis, preoperative EUS-FNA in resectable pancreatic cancer was associated with significantly greater overall survival when compared to the non-FNA group with no significant difference in rate of tumour recurrence and/or peritoneal seeding. These findings are limited by the retrospective nature of the included studies; randomized controlled trials are needed to confirm these results.

Funding Agencies

None

A2 THE BOWEL CLEANSING NATIONAL INITIATIVE (BCLEAN): PREDICTORS OF INADEQUATE BOWEL PREPARATION

Background

Adequate bowel cleansing before colonoscopy is, in theory, a simple concept but the high rate of inadequate or incomplete bowel cleanliness and its consequences have been the subject of many studies, guidelines, and meta- analyses. The complexity resides in all the pre-endoscopic factors surrounding preparation intake that may? influence quality of the bowel preparation.

Aims

To identify preendoscopic variables associated with inadequate bowel preparation

Methods

In this randomized trial conducted in adult outpatients in 10 Canadian hospitals, all early morning (AM) colonoscopies were scheduled between 7h30AM and 10h30AM and patients were randomized to PEG low volume or high- volume split-dose or high- volume day before. Later colonoscopies (PM) were scheduled between 10h30AM and 16h30PM and patients were randomized to PEG low-volume or high- volume split-dose or low- volume same day. A secondary random allocation assigned patients to a clear fluid or low residue diet. Inadequate bowel preparation was identified on the Boston Bowel Preparation Scale with a total score <6 with any of the 3 colonic segments subscores <2). All preendoscopic variables such as patients related factors, diet and type of bowel preparation were evaluated between groups with chi-square, Fisher’s exact or t-test where appropriate. All variables found to be significantly associated with a clean preparation on univariable analysis at the P=0.15 level were used to construct a multivariable model. Because of stratified randomization by time with possible resulting differing confounders, AM and PM patients were analysed separately.

Results

Over 29 months, 1726 patients were stratified in the AM group and 1750 patients in the PM group. 16.9% had inadequate bowel preparation in the AM group and 9.8% in the PM group. Pre-endoscopic variables associated with an inadequate bowel cleanliness in AM colonoscopy were a non screening indication (OR 1.36, 95%CI 1.04–1.78), a Charlson score>0 (OR 1.36, 95% 1.03–1.80) and a low residue diet (OR 1.53, 95%CI 1.17–2.01). Amongst PM colonoscopies, variables associated with an inadequate bowel cleanliness were increased age (OR 1.03, 95% 1.01–1.04), a non screening indication (OR 1.90 95%CI 1.35–2.70); a Charlson score>0 (OR 1.63, 95%CI 1.15–2.32), and a low residue diet (OR 1.41, 95%CI 1.01; 1.98).

Conclusions

In this large randomized trial, amongst patients undergoing an AM colonoscopy, pre- endoscopic factors associated with an inadequate bowel preparation were a non screening indication, comorbidities and a low residue diet. Amongst PM colonoscopy patients, in addition to these variables, an increased age was also associated with an inadequate bowel preparation.

Funding Agencies

received arm-length funding from Pendopharm Inc.

A274 EARLY SINGLE-OPERATOR CHOLANGIOSCOPY ASSISTED ELECTROHYDRAULIC LITHOTRIPSY (SOC-EHL) IN THE MANAGEMENT OF DIFFICULT BILIARY STONES IS COST-EFFECTIVE WHEN COMPARED TO A DELAYED STEP-UP APPROACH TO LATER SOC-EHL

Background

Single-operator cholangioscopy assisted electrohydraulic lithotripsy is the standard of care for difficult common bile duct (CBD) stones with failed clearance using standard ERCP. This technology is expensive and optimal timing of its use in terms of cost-effectiveness in the management algorithm of patients with difficult CBD stones remains unclear

Aims

To determine the cost-effective timing of SOC-EHL utilization in the management of difficult CBD stones

Methods

A decision model was developed assessing 4 strategies and progressively delayed introduction of SOC-EHL in relation to ERCP over 6-months. Difficult stones were defined as having failed CBD clearance via standard ERCP. Probability estimates for each health state were obtained from a literature systematic review. For each strategy, outpatients undergoing ERCP underwent different timings of SOC-EHL introduction from the first to the fourth ERCP and were followed for subsequent need for re-intervention, adverse events, need for surgery, and/or successful endoscopic CBD clearance. The unit of effectiveness was complete CBD clearance without need for surgery. Deterministic sensitivity analyses were performed varying all 50 model variables across ranges spanning 30% of their respective values. Costs are in 2018US$ based on US data.

Results

Performing SOC-EHL immediately during the first ERCP is the least expensive approach when compared to delaying SOC-EHL. This strategy costs $15,528 on average per patient with CBD clearance avoiding surgery and can save between $260 to $720 compared to the 3 other strategies, which introduce SOC-EHL during the second to the fourth ERCP. Effectiveness is clinically comparable between the four strategies ranging from 97–99%. Deterministic sensitivity analysis shows changes in the results when the ERCP complication rate (baseline probability of 6%) decreases to 4.5%, when the SOC-EHL (baseline costs of $2,450) costs more than $2,670, or when the ERCP facility fees (baseline costs of $4,292) are less than $3,425. In all 3 scenarios, delaying the first SOC-EHL use to the fourth procedural attempt becomes the dominant strategy. Variations of the other 47 variables did not alter results.

Conclusions

Although SOC-EHL is expensive, this analysis demonstrates that among patients who have failed a prior attempt at stone extraction, utilization of SOC-EHL at the next (first subsequent) ERCP is less costly when compared to its delayed introduction. However, postponing the use of SOC-EHL to the fourth ERCP could be identified as the most cost-effective strategy when facility fees or ERCP complications rates are below certain thresholds, or when the costs of SOC-EHL extend beyond a defined threshold.

Funding Agencies

None

A1 COLONOSCOPY FINDINGS FOLLOWING A FECAL IMMUNOCHEMICAL TEST: A RETROSPECTIVE STUDY ASSESSING THE SCREENING TEST PERFORMANCE

Background

Fecal Immunochemical Testing (FIT) is the preferred test for colorectal cancer screening in the average risk population in Canada.

Aims

This study aims to assess colonoscopy findings in patients who have undergone a FIT within the previous 2 years.

Methods

This retrospective study included all adult patients that have undergone a single diagnostic colonoscopy from March 2013 to March 2016 following a single FIT test at the CIUSSS de l’Estrie, a tertiary hospital. The primary outcome was to evaluate rates of clinically significant lesion when comparing FIT positive (FIT+) to FIT negative (FIT-) colonoscopy, using Quebec’s current threshold of 175 ng/ml of hemoglobin. Secondary outcomes included all other type of lesions, delays between FIT testing and colonoscopy, procedural time, caecal intubation rates and withdrawal time.

Results

Overall, 2230 patients were included, aged 62.0±10.5 years, 55.0% were female and 26.1% had a positive FIT. Patients with a positive FIT had a significantly higher polypectomy rate (62.4% vs 41.3%, p<0.01) and higher number of polyps per patient (2.9±2.5 vs 2.1±1.5, p<0.01). FIT+ had significantly higher rates of adenocarcinoma (3.4% vs 0.7%, p<0.01) with 11 out of 31 patients bearing a negative FIT with the current threshold. No difference was found for sessile serrated polyps (7.8% vs 6.0%, p=0.13). Patients with a FIT+ had significantly higher advanced adenomas (24.0% vs 5.6%, p<0.01), proximal polyps (33.6% vs 22.4%, p<0.01), distal polyps (52.8% vs 28.2%, p<0.01), non-advanced adenomas (38.5% vs 23.9%, p<0.01) and benign polyps (25.1% vs 17.2%, p<0.01). Patients with FIT+ received their colonoscopy 7.5 months earlier than FIT- patients (3.3±2.2 vs 10.8±8.3 months, p<0.01). FIT+ also yielded a significant longer procedural time (28.5±14.1 vs 25.5±12.1, p<0.01) but no difference was noted for caecal intubation rates and withdrawal time (93.3% vs 94.0%, p=0.55 and 14.0±8.4 vs 12.0±7.7, p=0.20 respectively). Results were similar when lowering the threshold to 150, 100, 75 and even 50 ng/ml. 8 patients with an adenocarcinoma had a FIT level lower than 50 ng/ml.

Conclusions

Patients with a colonoscopy and a positive FIT have higher rates of significant findings. Although commonly used for colorectal cancer screening, FIT still failed to detect almost 30% of adenomas and adenocarcinomas found during colonoscopy. It also does not perform very well for serrated polyps. Our data also fails to show an improved yield of the FIT when lowering the its threshold from 175 to 50. There is still a great need for a more sensitive non-invasive colon cancer screening test.

Funding Agencies

None

A279 EUS-GUIDED BILIARY DRAINAGE IN MALIGNANT DISTAL BILIARY OBSTRUCTION: AN INTERNATIONAL SURVEY TO IDENTIFY BARRIERS OF TECHNOLOGY IMPLEMENTATION

Background

Endoscopic ultrasound-guided biliary drainage (EUS-BD) is a promising alternative to endoscopic retrograde cholangiopancreatography (ERCP) in malignant distal biliary obstruction (MDBO). Recent small randomized controlled trials comparing EUS-BD with ERCP suggest that EUS-BD achieves a similar technical success rate and safety profile while potentially being associated with lower rates of stent dysfunction However, its application in clinical practice has been impeded by various undefined barriers.

Aims

To evaluate the current practice of EUS-BD and the determinants for its clinical implementation in MDBO.

Methods

An online survey was generated using Google Forms. Five endoscopy societies have distributed the survey as of October 10th, 2019. Survey questions measured participant characteristics, EUS-BD in different clinical scenarios, and potential barriers to implementation. Descriptive statistics were calculated using frequencies, chi-square statistics were used for inferential analysis, and a standard step-wise multivariable analysis was performed to identify independent variables for and against the use of EUS-BD.

Results

To date, 102 physicians have participated in the survey (response rate 7.97%). The majority of participants are from North America (39.2%), Asia (31.4%), and Europe (19.6%). Most participants are gastroenterologists with formal therapeutic endoscopy training (66.7%), though only 28.4% have received EUS-BD training. In unresectable cancer, 85.1% of respondents favoured EUS-BD over percutaneous biliary drainage following ERCP failure (p<0.0001), while in borderline resectable disease, 72.3% preferred EUS-BD. On multivariable analysis, male gender, formal training in EUS-BD, and unresectable cancer were independent variables for the use of EUS-BD. Conversely, independent discouraging factors for EUS-BD included fear of adverse events, limited high-quality data, lack of local expertise, and inadequate access to EUS technology.

Conclusions

In this international survey, it appears that EUS-BD is gaining traction, especially in the setting of unresectable disease following ERCP failure. However, barriers to implementation include the lack of high-quality data, fear for adverse events, limited experts in the field, and inadequate access to EUS technology. This suggest the need for high-quality clinical trials, increased endoscopist training in this field, and further technology development in EUS-BD in order to increase its uptake in clinical practice.

Funding Agencies

None

Somatosensory-guided tool use modifies arm representation for action

Tool-use changes both peripersonal space and body representations, with several effects being nowadays termed tool embodiment. Since somatosensation was typically accompanied by vision in most previous tool use studies, whether somatosensation alone is sufficient for tool embodiment remains unknown. Here we address this question via a task assessing arm length representation at an implicit level. Namely, we compared movement’s kinematics in blindfolded healthy participants when grasping an object before and after tool-use. Results showed longer latencies and smaller peaks in the arm transport component after tool-use, consistent with an increased length of arm representation. No changes were found in the hand grip component and correlations revealed similar kinematic signatures in naturally long-armed participants. Kinematics changes did not interact with target object position, further corroborating the finding that somatosensory-guided tool use may increase the represented size of the participants’ arm. Control experiments ruled out alternative interpretations based upon altered hand position sense. In addition, our findings indicate that tool-use effects are specific for the implicit level of arm representation, as no effect was observed on the explicit estimate of the forearm length. These findings demonstrate for the first time that somatosensation is sufficient for incorporating a tool that has never been seen, nor used before.

Abstract P2-09-12: Perilymphatic IRX-2 cytokine therapy to enhance tumor infiltrating lymphocytes (TILs) and PD-L1 expression preceding curative-intent therapy in early stage breast cancer (ESBC)

Background: Cytokines are being explored as a therapeutic strategy to modulate the tumor microenvironment and facilitate immunotherapy benefit in breast cancer. Here, we investigate a locoregional therapeutic approach whereby cytokines (IRX-2) are administered into the subcutaneous peri-areolar tissue (in an anatomic distribution similar to sentinel lymph node mapping) to facilitate immune cell recruitment/activation within the draining lymph nodes and tumor in ESBC. IRX-2 is derived from ex vivo phytohemagglutinin-stimulated lymphocytes and contains multiple cytokines including IL-1β, IL-2, TNF-α, IFN-γ, IL-6, IL-8, and GM-CSF, with stable concentrations from lot to lot. Preclinically, IRX-2 activates T-cells and natural killer (NK) cells, facilitates antigen presentation, and enhances activity of anti-PD-1/L1 in a SCC7 model. In a preceding head/neck squamous cell carcinoma phase I trial, perilymphatic IRX-2 was safe and increased TILs. Here, we report the final clinical results of a phase Ib trial evaluating the feasibility and immunologic activity of IRX-2 in ESBC.

Methods: Beginning 21 days prior to surgical resection, enrolled operable patients with stage I-III ESBC (all subtypes) received the pre-operative IRX-2 regimen consisting of a single low-dose cyclophosphamide (300 mg/m2 to facilitate T-regulatory cell depletion), followed by 10 days of subcutaneous peri-areolar IRX-2 injections into the affected breast (1 mL × 2 at tumor axis and at 90°). Endpoints were feasibility (primary endpoint), stromal TIL (sTIL) count (pre-treatment versus post-treatment, blinded average of two pathologist reads using San Antonio H&E sTIL guidelines), PD-L1 expression (Nanostring) and enumeration of peripheral immune cells by flow cytometry.

Results: All patients (n=16/16) completed and tolerated the regimen with no surgical delays or treatment-attributed grade III/IV toxicities. Common adverse events (occurring in >15% subjects) attributed to IRX-2 injections were: injection site reaction (grade 1, n=8/16), bruising (grade 1, n=7/16), and pain (grade 1, n=3/16). Common adverse events attributed to low-dose cyclophosphamide were: fatigue (grade 1, n=5/16) and nausea (grade 1/2, n=3/16). Treatment was associated with an increase in sTIL score (Wilcoxon signed-rank p=.04), with 4/10 sTIL-low tumors (0-10% score) re-categorized to sTIL-moderate (11-50% score). Increases in PD-L1 RNA expression were observed (Wilcoxon signed-rank p=.04) in 12/16 tumors (median 57% increase, range: -53% to 185% increase), as well as increases in Nanostring NK and Th1 cell signatures. In blood, increases in CD4 and CD8 effector T-cell activation (ICOS, HLA-DR, and CD38) and T-reg depletion were observed.

Conclusions: IRX-2 was well tolerated with preliminary evidence of sTIL increase, PD-L1 upregulation, and peripheral lymphocyte activation. Based upon these data and preclinical evaluations demonstrating synergy with checkpoint inhibition, the IRX-2 regimen is being evaluated for clinical efficacy in conjunction with pembrolizumab and neoadjuvant chemotherapy (doxorubicin, cyclophosphamide, paclitaxel) in patients with stage II-III triple negative breast cancer.

Citation Format: Pucilowska J, Egan JE, Berinstein NL, Moxon N, Aliabadi-Wahle S, Imatani JH, Conlin A, Acheson A, Massimino K, Martel M, Campbell M, Wu Y, Sun Z, Redmond W, Shah M, Urba WJ, Page DB. Perilymphatic IRX-2 cytokine therapy to enhance tumor infiltrating lymphocytes (TILs) and PD-L1 expression preceding curative-intent therapy in early stage breast cancer (ESBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-09-12.

Abstract P2-09-03: Updated efficacy of first or second-line pembrolizumab (pembro) plus capecitabine (cape) in metastatic triple negative breast cancer (mTNBC) and correlations with baseline lymphocyte and naïve CD4+ T-cell count

Background: In mTNBC, anti-PD-1/L1 monotherapy is most effective when administered early in the course of disease, with recent trials demonstrating overall response rates (ORR) of 23-26% in the first-line setting and 5-6% in later lines. This may reflect iatrogenic lymphopenia from preceding cytotoxic chemotherapy. Furthermore, curative-intent chemotherapy is associated with prolonged suppression of naïve CD4+ cells, a T-cell subset that may play a critical role in the generation of de novo anti-tumor immune responses. We present the final clinical results of a pilot study evaluating the safety and efficacy of combining pembrolizumab plus standard-of-care capecitabine in the first/second-line mTNBC setting. We also explore potential associations between clinical benefit and lymphopenia, preceding chemotherapy, and absolute naïve CD4+ counts.

Methods: In a pilot study, we evaluated the tolerability and preliminary efficacy of concurrent pembro (200mg IV q21 day) plus investigator-selected 1st/2nd line paclitaxel (80mg/m2 IV weekly) or oral cape (2,000mg BID, weekly 1 on/1 off). The primary endpoint was tolerability, defined as the proportion of subjects receiving >6 weeks concurrent therapy without dose discontinuation with toxicities reported per CTCAE v4.0. The secondary endpoint was 12-week objective response rate (ORR) by RECIST1.1. Exploratory endpoints included peripheral blood cell enumeration by real-time flow cytometry and routine clinical laboratory. Naïve CD4+ cells were defined as CD45+ CD3+ TCRab+ CD4+ CD45RA+ CCR7+. Here, we report the results of the pilot phase of the cape cohort (NCT02734290).

Results: Twelve of 14 subjects were treated in the first-line setting. All subjects (14/14, 100%) tolerated cape+pembro for >6 weeks, with toxicities consistent with monotherapy cape experience (diarrhea: grade I-II 50%, grade III 7%; hand-foot: grade I-II 71%) that improved with dose-reduction as needed. At 12 weeks, the ORR was 6/14 (42.9%), and the clinical benefit rate (ORR + stable disease) was 8/14 (57.1%). Depressed absolute lymphocyte count at baseline (ALC<1.0/uL: 33% CBR; ALC≥1.0/uL: 75% CBR) and recent exposure to cytotoxic chemotherapy (<6 months: 33% CBR; >6 months: 75% CBR) were associated with reduced clinical benefit. By flow cytometry, subjects experiencing clinical benefit had higher baseline absolute naïve CD4+ counts (average 283 cells/uL v. 93 cells/uL, p=.069).

Conclusions: This study met the primary endpoint of safety for cape plus pembro in mTNBC, with encouraging clinical activity. These data are supportive of further studies evaluating combination chemotherapy plus anti-PD-1/L1 mTNBC. We observed greater clinical benefit in subjects with non-suppressed ALC, less exposure to recent chemo, and higher baseline naïve CD4+ counts, suggesting that iatrogenic immunosuppression can impair response to immune checkpoint therapy in mTNBC. These findings should be confirmed in ongoing randomized trials of immune checkpoint +/- chemotherapy in mTNBC, and should be considered in the design of future clinical trials.

Citation Format: Page DB, Pucilowska J, Bennetts L, Kim I, Sanchez K, Martel M, Conlin A, Moxon N, Mellinger S, Acheson A, Kemmer K, Mitri Z, Vuky J, Ahn J, Abaya C, Manigault T, Basho R, Urba WJ, McArthur HL. Updated efficacy of first or second-line pembrolizumab (pembro) plus capecitabine (cape) in metastatic triple negative breast cancer (mTNBC) and correlations with baseline lymphocyte and naïve CD4+ T-cell count [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-09-03.

BOARD-INVITED REVIEW: Quantifying water use in ruminant production

The depletion of water resources, in terms of both quantity and quality, has become a major concern both locally and globally. Ruminants, in particular, are under increased public scrutiny due to their relatively high water use per unit of meat or milk produced. Estimating the water footprint of livestock production is a relatively new field of research for which methods are still evolving. This review describes the approaches used to quantify water use in ruminant production systems as well as the methodological and conceptual issues associated with each approach. Water use estimates for the main products from ruminant production systems are also presented, along with possible management strategies to reduce water use. In the past, quantifying water withdrawal in ruminant production focused on the water demand for drinking or operational purposes. Recently, the recognition of water as a scarce resource has led to the development of several methodologies including water footprint assessment, life cycle assessment, and livestock water productivity to assess water use and its environmental impacts. These methods differ with respect to their target outcome (efficiency or environmental impacts), geographic focus (local or global), description of water sources (green, blue, and gray), handling of water quality concerns, the interpretation of environmental impacts, and the metric by which results are communicated (volumetric units or impact equivalents). Ruminant production is a complex activity where animals are often reared at different sites using a range of resources over their lifetime. Additional water use occurs during slaughter, product processing, and packaging. Estimating water use at the various stages of meat and milk production and communicating those estimates will help producers and other stakeholders identify hotspots and implement strategies to improve water use efficiency. Improvements in ruminant productivity (i.e., BW and milk production) and reproductive efficiency can also reduce the water footprint per unit product. However, given that feed production makes up the majority of water use by ruminants, research and development efforts should focus on this area. More research and clarity are needed to examine the validity of assumptions and possible trade-offs between ruminants' water use and other sustainability indicators.

Remarkably High Frequency of EGFR Expression in Breast Carcinomas with Squamous Differentiation

The human epidermal growth factor receptor (EGFR) is reportedly overexpressed in 15-20% of breast carcinomas. EGFR overexpression is associated with reduced survival and is inversely correlated with expression of estrogen receptor (ER). This study assessed EGFR expression in breast carcinomas with squamous differentiation. The immunohistochemical (IHC) expression of EGFR was evaluated in 39 breast carcinomas with squamous differentiation (30 pure squamous, 6 adenosquamous, 3 carcinosarcomas) by use of the pharmDx assay (clone 2-18C9, DakoCytomation®). Cases were considered positive if at least 10% of the cells showed 1+ positivity in the squamous component. Squamous differentiation was confirmed with IHC for CK5-6 (clone D5/16B4, DakoCytomation®). ER, PR, and HER2 status as well as clinical information regarding treatment and outcome were correlated. As a control, a tissue microarray comprising 280 lymph node positive breast carcinomas was evaluated with the same EGFR assay. The 39 patients ranged in age from 33 to 77 years (mean 52). The tumors measured 1.3-30 cm (mean 4.8). Sentinel or full axillary lymph node dissection was performed in 28 patients. Fourteen patients had positive lymph nodes. At the time of initial diagnosis, 3 patients had distant metastasis. Follow-up was available for 16 patients (mean 45 months). Disease-free survival at 3 years was 70%. Among the 39 tumors 87% (34) were positive for EGFR (p<0.0001). Sixty-nine percent (27 of 39) showed >50% 2+ EGFR staining. EGFR-positive tumor cells (showing squamous morphology) were also found in 1 bone, 1 lung, and 8 of 11 lymph node metastases available for evaluation. All 11 lymph nodes showed squamous differentiation. All but 1 of the EGFR+ tumors examined were ER and PR negative. Six EGFR-positive tumors were HER2 positive. No statistically significant differences in HER2 status, size, lymph node status and disease-free survival were observed between EGFR+ and EGFR-cases, but the number of EGFR-negative tumors was quite small. Nine of 280 (3%) of lymph node-positive invasive carcinomas on the tissue microarray were EGFR+; review of the initial diagnostic slides failed to reveal squamous features in all but 1 of the 9 EGFR+ tumors. Breast carcinomas with squamous differentiation are a distinct subgroup of breast tumors with a very high frequency of EGFR positivity. Breast carcinomas of this type would be ideal candidates for a trial with EGFR inhibitors.

Measures of trainee performance in advanced endoscopy: A systematic review

INTRODUCTION

The diversity, technical skills required, and risk inherent to advanced endoscopy techniques all contribute to complex training curricula and steep learning curves. Since trainees develop endoscopy skills at different rates, there has been a shift towards competency-based training and certification. Validated endoscopy performance measures for trainees are, therefore, necessary. The aim of this systematic review was to describe and critically assess the existing evidence regarding measures of performance for trainees in advanced endoscopy.

METHODS

A systematic review of the literature from January 1980 to January 2016 was carried out using the MEDLINE, EMBASE, CENTRAL, and ISI Web of knowledge databases. MeSH terms related to 'advanced endoscopy' and 'performance' were applied to a highly sensitive search strategy. The main outcomes were face, content, and construct validity, as well as reliability.

RESULTS

The literature search yielded 1,662 studies and 77 met the inclusion criteria after abstract and full-text review (endoscopic retrograde cholangiopancreatography (ERCP)=23, endoscopic ultrasound (EUS)=30, colonoscopic polypectomy (CP)=11, balloon-assisted enteroscopy (BAE)=7, luminal stenting=3, radiofrequency ablation (RFA)=2, and endoscopic muscosal resection (EMR)=1). Good validity and reliability were found for measurement tools of overall performance in ERCP, EUS and CP, with applications for both patient-based and simulator training models. A number of specific technical skills were also shown to be valid measures of performance. These include: selective biliary cannulation, sphincterotomy, biliary stent placement, stone extraction and procedure time for ERCP; pancreatic solid mass T-staging, EUS-guided fine needle aspiration (EUS-FNA) procedure time, number of EUS-FNA passes and puncture precision for EUS; procedure time and en bloc resection rate for CP; retrograde fluoroscopy time for BAE; and mean number of endoscopy sessions required to achieve complete eradication of intestinal metaplasia (CIEM) for RFA. The evidence for EMR and luminal stenting is of insufficient quality to make recommendations.

CONCLUSIONS

We have identified multiple valid and readily available performance measures for advanced endoscopy trainees for ERCP, EUS, CP, BAE and RFA procedures. These tools should be considered in advanced endoscopy training programs wishing to move away from apprenticeship-based training and towards competency-based learning with the help of patient-based and simulator tools.