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FIGURE 1: (A) Cross-sectional view using VLE of a segment of BE previously treated withRFA. (B) Neosquamous epithelium is characterized by a layered structure that is absent in(C) specialized intestinal metaplasia. Measurements of NSE thickness (red double arrow)were taken at four quadrants (Q1-4) along each centimeter of the pre-RFA BE segment.Quadrants that contained both NSE and SIM were excluded from measurement (gray rectan-gle involving Q2 and Q3).

Mo1925

Cellular Senescence and P16ink4a Immunohistochemistry Predicts Responseto Radiofrequency Ablation (RFA) for Barrett's Esophagus (BE) With High-grade Dysplasia (HGD)Joshua D. Penfield, Cadman L. Leggett, Marlys Anderson, Lori S. Lutzke, Tsung-Teh Wu,Alan R. Zinsmeister, Prasad G. Iyer, Kenneth K. Wang

BACKGROUND: Cellular senescence is a state of permanent cell growth arrest that occursas a response to neoplastic stimuli and appears to prevent progression of neoplasia. Thepresence of markers of senescence in BE with HGD prior to ablative therapy may predictresponse to RFA, as escape from senescence promotes aggressive behavior of dysplastic cells.As identification of senescence in paraffin-embedded tissue is difficult to achieve withstandard methods, we chose biomarkers that were compatible. We hypothesized that therewould be a difference in senescence biomarkers and stem cells between patients whoresponded and those who did not respond to RFA. AIM: To evaluate whether senescencebiomarkers can predict response to RFA by using immunohistochemistry against the tumorsuppressor protein p16INK4a, the nuclear DNA damage response marker γ-H2Ax and theintestinal stem cell marker LGR5 in biopsy tissue from BE patients with HGD prior to RFA.METHODS: All patients referred for untreated BE with HGD were reviewed. Patients withpre-RFA esophageal biopsies, two RFA treatment sessions and surveillance biopsies 3 monthspost-RFA were identified. From this group, patients were selected as either persistent HGD[non-responders (NR)] or neosquamous re-epithelialization [responders (R)]. Pre-RFA tissuewas then stained with p16INK4a, γ-H2Ax and LGR5. Slides were reviewed by an experiencedGI pathologist blinded to the status of the patients. An intensity-weighted scoring systemwas used. RESULTS: Forty five patients (R:25, NR:20) fulfilled inclusion criteria. Baselinecharacteristics are shown in table 1. Using a logistic model to predict RFA response, meancell count of γ-H2Ax (R:110 vs. NR:76, p.0.05) and LGR5 (R:10 vs. NR:13, p.0.05) werenot significantly associated with response to RFA. Decreased intensity of p16INK4a in pre-RFA tissue was associated with persistent HGD post-RFA (OR=2.78, 95% CI 1.16-6.66; p=0.02). CONCLUSION: In our cohort of patients, p16INK4a intensity was associated withRFA response as patients with decreased expression of this tumor suppressor protein onpre-RFA tissue were more likely to have persistent HGD post-RFA. This is likely due to adecreased senescence response in pre-RFA tissue that promotes resistance to ablation.Table 1: Patient demographics

Figure 1: A) and B) Representative images of p16INK4a immunohistochemistry on pre-RFAbiopsy tissue from patients with subsequent complete neosquamous re-epithelialization post-RFA. C) and D) Representative images of p16INK4a on pre-RFA biopsy tissue from patientswith subsequent persistent HGD post-RFA.

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Mo1926

Effects of Vitamin D Supplementation on Barrett's EsophagusLinda C. Cummings, Joseph Willis, Gregory S. Cooper, Beth Bednarchik, SanfordMarkowitz, Amitabh Chak

Background: Vitamin D directly or indirectly controls genes that regulate proliferation,apoptosis, and differentiation. We have previously reported that calcitriol, the active formof vitamin D, inhibits the growth of esophageal adenocarcinoma cell lines. Vitamin Ddeficiency is also associated with insulin resistance and increased risk for esophageal cancer.The goals of this study were to assess the effects of vitamin D supplementation on Barrett'sesophagus (BE) patients with or without dysplasia. We hypothesized that vitamin D supple-mentation may have beneficial effects including improvement of dysplasia and insulin resis-tance in BE. Methods: Patients with long-segment or short-segment BE with or without highgrade dysplasia (HGD) were treated with vitamin D3 (cholecalciferol) 50,000 internationalunits weekly for 2 weeks (HGD) or 12 weeks (no dysplasia or low grade dysplasia). BEbiopsies and blood samples were obtained before and after vitamin D3 supplementation.Biopsies were stained with hematoxylin and eosin and reviewed by an expert pathologistblinded to study arm. Serum 25-hydroxyvitamin D, insulin, and glucose levels were assessedto characterize vitamin D status and to estimate insulin resistance (IR) by the HomeostaticModel Assessment (HOMA). Results: Among the first 10 evaluable study subjects, 7 hadBE with no or low grade dysplasia and 3 had high grade dysplasia. 6 patients had long-segment BE and 4 had short-segment. The mean age was 65.6 years (standard deviation,9.6 years); 3 women and 7 men were enrolled. Baseline serum 25-hydroxyvitamin D levelsranged from 14.1 ng/mL (deficient) to 60.9 ng/mL (sufficient) with a median level of35.4 ng/mL. Median baseline HOMA-IR was 4.27. After vitamin D supplemention, 25-hydroxyvitamin D levels rose significantly (p, 0.001) with a median increase of 35.2 ng/mL among patients with no or low grade dysplasia. Among patients with HGD with 2 weeksof supplementation, 2 had small increments in serum 25-hydroxyvitamin D levels of 13.3and 14.2 ng/mL, while no change occurred in 1 patient. On pathologic review, regressionto low grade dysplasia after vitamin D supplementation occurred in 2 of 3 HGD subjects.There was no significant change in insulin resistance after vitamin D supplementation.Vitamin D supplementation was well tolerated. Conclusion: Regression to low grade dysplasiaoccurred in 2 of 3 high grade dysplasia subjects. Baseline Vitamin D status of BE patientswas generally sufficient. Treatment with 12 weeks of vitamin D supplementation resultedin marked increases in serum 25-hydroxyvitamin D levels compared with 2 weeks. Thesechanges occurred independent of effects on insulin resistance. These findings support thehypothesis that vitamin D supplementation may have beneficial effects in Barrett's esophagusand warrant further investigation.

Mo1927

Complete Remission of Intestinal Metaplasia After One RadiofrequencyAblation SessionBashar J. Qumseya, Waseem J. David, Edgar C. Aranda-Michel, Lois L. Hemminger,Michael B. Wallace, Herbert C. Wolfsen

Background: Radiofrequency ablation (RFA) is the most commonly used for treatment ofBarrett's esophagus (BE) with the goal of achieving complete remission from intestinalmetaplasia (CRIM). Endoscopic mucosal resection (EMR) is used in conjunction with RFAto remove nodular and other suspicious areas. Impact of EMR on CRIM is uncertain withpotential to improve CRIM by removal of nodular/thick tissue which is difficult to ablateby RFA, but also potential to worsen RFA by inducing stenosis and altered esophagealgeometry. Aims: To assess the effect of one treatment with RFA with/without EMR on therate of CRIM among patients with BE. Methods: This was a retrospective, observationalstudy using large RFA database in a tertiary referral center. The primary outcome was therate of CRIM after the first RFA session compared between patients who had RFA alone vs.RFA with EMR. A secondary outcome was the achievement of complete remission fromdysplasia (CRD) downgrade in pathology from baseline. Chi-square or Fisher's exact testswhere used to assess differences between proportions. Multivariable logistic regression analy-sis was used to assess the association between the primary outcome (CRIM) and predictorvariables. Results: 215 patients underwent RFA for BE between May 2005 and June 2012.Of those 23% (49) has nondysplastic BE (NDBE), 6.5% (14) were indefinite for dysplasia(IFD), 29% (63) has low-grade dysplasia (LGD), 36% (77) had high-grade dysplasia (HGD),and 5.5% (12) had adenocarcinoma (AC). Most patients (91%) were males. Half of allpatients (50%) had a history of ever having EMR. However, a minority of patients (11%)had EMR to remove nodules within 3 months of initiating RFA. Pathology on follow upEGD based on baseline pathology is summarized in Figure 1. Overall 36% [29-42%] achievedCRIM after one RFA treatment. Among 166 patients with BE and dysplasia, 46% (76)achieved complete remission of dysplasia (CRD) after one session of RFA. In a univariateanalysis there was no significant difference in the rate of CRIM after the first RFA betweenpatients who had RFA with EMR or RFA alone (50% vs. 34%, p=0.17). In a multivariablelogistic regression analysis when controlling for age, gender, and BE length, RFA with EMRshowed a trend toward more CRIM (OR 2.5 [0.96 - 6.6], p=0.06) when compared to RFAalone, but this did not achieve statistical significance. Conclusion: Many patients can achieveCRIM after one RFA treatment. Use of EMR to remove nodules before RFA may be associatedwith higher rates of CRIM after RFA. Larger studies are needed to confirm this association.

Mo1928

Factors Associated With Recurrence of Barrett's Esophagus After Completionof Radiofrequency AblationPeter Shue, Rahul Kataria, Murali Pathikonda, Frank K. Friedenberg, Rebecca Thomas,Michael S. Smith

Background: Despite the efficacy of radiofrequency ablation (RFA) in eradicating Barrett'sesophagus (BE), prior studies have reported recurrence of intestinal metaplasia (IM) anddysplasia after complete remission (CR) is achieved. There is limited data on factors thatpredict recurrence. Our aim was to identify factors associated with the recurrence of IMand/or dysplasia after CR is achieved with RFA. Methods: All BE patients at a single academicmedical center who received RFA from January 2009-October 2012 were identified. Patientswere included in the analysis if they achieved CR of IM, defined by the absence of endoscopicand histologic evidence of Barrett's metaplasia on initial post-ablation endoscopy, and hada minimum of two surveillance endoscopies at least three months apart. Surveillance biopsieswere obtained using a modified Seattle protocol. Clinical, demographic and endoscopic datawere collected. Univariate analysis using Pearson-Chi square for categorical variables andindependent sample t-test for continuous variables was performed. Results: Forty-two patients(15 with non-dysplastic BE (NDBE); 13 with low grade dysplasia (LGD), 12 with high gradedysplasia (HGD) and 2 with intramucosal carcinoma) met criteria. This cohort was 71%male with a median age of 61 years (IQR 53-70). The median BE length was 3.5 cm (IQR1-5). A median of 3 ablations (IQR 2-4) were required to achieve CR of IM, with a medianfollow-up period of 14 months (IQR 11-22.5). The overall IM recurrence rate was 26.2%(n=11). Recurrence was seen in 5 (33.3%) patients with NDBE, 4 (30.1%) with LGD, and2 (18.0%) with HGD. The difference in recurrence rates between dysplasia grades was notsignificant (p=0.681). The median time to recurrence was 12 months (IQR 9-20). Therewas no recurrence of dysplasia. Twenty-eight (66.7%) patients had a smoking history. Amongthese smokers, 11 (39.3%) recurred. No recurrence was seen among non-smokers. Thedifference in recurrence rate between smokers and non-smokers was significant (p = .006).However, there was no significant difference when comparing former to active smokers (p=0.12). Patients with recurrence had a significantly lower body mass index (BMI) comparedto patients who did not recur (25.3 kgm-2 vs 29.8 kgm-2, p=0.002). Other parameters suchas age, gender, race, alcohol consumption, family history of BE or esophageal cancer, initialBE length, hiatal hernia size and presence of gastroesophageal reflux symptoms were notsignificantly associated with recurrence. Conclusion: Recurrence after achieving CR of IMwith RFA was 26.2%. These recurrences were seen exclusively in smokers, suggesting thatsmoking may be a risk factor. Surprisingly, patients with recurrence had a lower BMI,which may indicate that obesity is not a predisposing factor. Further studies are needed tounderstand these associations.

Mo1929

Effect of Site Volume on Eradication of Barrett's Esophagus (BE): ResultsFrom the U.S. RFA RegistrySarina Pasricha, William J. Bulsiewicz, V. Raman Muthusamy, Srinadh Komanduri,Herbert C. Wolfsen, Ron E. Pruitt, Atilla Ertan, Gary W. Chmielewski, Nicholas J.Shaheen

Background: Radiofrequency ablation (RFA) may require multiple sessions for completeeradication of Barrett's esophagus (BE). The impact of case volume on safety and efficacyoutcomes associated with RFA is unclear. Methods: The U.S. Barrett's RFA Patient Registryis a multi-center prospective study of patients undergoing RFA for BE from 2007 to 2012.We collected demographic data, pre- and post- treatment histology, endoscopic findings,number of RFA sessions, ablation outcomes (including complete eradication of intestinalmetaplasia (CEIM), and complete eradication of dysplasia (CED)), and complications (stric-ture, bleeding, hospitalization). Our safety cohort consisted of patients treated with RFA,while our efficacy cohort was restricted to subjects who had a biopsy performed 12 monthsor more after initial treatment. We examined the effect of center volume at the time of anindividual's enrollment by examining safety and efficacy outcomes based upon the numberof patients treated at a center prior to an individual's enrollment in 4 patient groups (Patients1-10, 11-20, 21-30, and more than 30). The effect of center experience on stricture, bleeding,hospitalization, and CEIM was assessed using logistic regression adjusting for age, gender,race, BE length, and presence of pretreatment dysplasia. The effect of center experience ontotal treatment sessions to achieve CEIM was examined using linear regression, controllingfor BE length. Results: Among 5,530 patients, the number of patients treated prior toenrollment at a site was not significantly associated with the risk of stricture, GI bleeding,perforation or hospitalization (p. 0.05)(see table). There was, however, a trend towardlower rates of hospitalization with added case volume. In a multivariate logistic regressionmodel, the odds of hospitalization decreased by 1% for each patient previously treated at

S-697 AGA Abstracts

the center (OR 0.99, p=0.02). Center experience was not independently associated withstricture or GI bleed after controlling for age, gender, race, BE length and pre-treatmentdysplasia. Among 2936 patients included in the efficacy analysis, degree of center experienceat the time of an individual's treatment session was significantly associated with improvementsin CEIM rate (p= 0.001) (see table), however this association dissolved in multivariableanalysis after controlling for age, gender, race, length and pre-treatment dysplasia(p=0.30).Patient volume did not impact CED rates. However, case volume was independently associ-ated with the number of treatment sessions needed to achieve CEIM, after controlling forBE length (p = 0.02; see figure). Conclusions: Increased site case volume was associatedwith lower hospitalization rates and fewer treatments needed to achieve CEIM but did notsignificantly affect rates of stricture, bleeding, or the efficacy of treatment.Safety and efficacy of RFA based on center experience prior to treatment:

Mo1930

Beneficial Effect of Ursodeoxycholic Acid (UDCA) and Its Derivative UDCA-Cpa in Attenuation of Functional Impairment of Esophageal Mucosa in RatModel of Barrett's EsophagusJolanta Majka, Rafal Pabianczyk, Gracjana Krzysiek-Maczka, Agata Ptak-Belowska,Slawomir Kwiecien, Anne-Marie Byrne, Dermot P. Kelleher, John Gilmer, TomaszBrzozowski

Barrett,s esophagus (BE) is a pre-malignant condition in which squamous epithelium isreplaced by metaplastic columnar epithelium, but the pathogenesis of this disorder shouldbe elucidated. The secondary bile acid deoxycholic acid (DCA) contributes to the developmentof BE and implicated in progression of BE to adenocarcinoma, whereas UDCA has shownsome protection in BE epithelial cell line in vitro. We studied effect of treatment with DCA,UDCA and the novel derivative UDCA (UDCA-CPA) on esophageal mucosal damage in ratsprepared with esophagogastroduodenal anastomosis (EGDA). EGDA rats were randomlydivided into 4 groups treated i.g. daily with: 1) vehicle (saline),2) DCA (20 mg/kg), 3)UDCA (40 mg/kg) or UDCA-CPA (40 mg/kg). At 8 and 12 weeks esophageal damage wasevaluated by macroscopic and histological lesion index (LI), esophageal blood flow (EBF),MPO activity and malonylodialdehyde (MDA) content. mucosal expression of mRNA forcaudal-related homebox gene family Cdx1 and Cdx2, COX-2, VEGF,NFκB and proinflamma-tory cytokines IL-1β and TNF-α was analyzed by RT-PCR. Chronic esophagitis developedin all EGDA animals and a significant decrease in EBF was observed. MPO activity andMDA content was elevated and an overexpression of Cdx2 and COX-2 were observed. InEGDA rats, extensive esophageal ulcerations, development of columnar epithelium, formationof mucus glands in squamous epithelium and intestinal metaplasia were observed. Treatmentwith DCA significantly enhanced LI, MPO activity and MDA content. Expression of IL-1 βand TNF-α mRNA and plasma concentration were elevated compared to vehicle. EGDAanimals treated with UDCA or UDCA-CPA, exhibited significantly less macro- and micro-scopic esophageal injury and fewer animals developed columnar epithelium and intestinalmetaplasia. Expression of NFκB was negligible in sham-control animals but strongly upregu-lated in esophageal mucosa of EGDA rats treated with DCA, but not in those treated with

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