Citations

Abstract The human IGHV4-34 gene encodes antibodies which are intrinsically autoreactive when the VH domain is unmutated. Therefore, B cells expressing IGHV4-34 B-cell receptor immunoglobulins (BcR IG) are normally under close scrutiny in order to avoid unwanted autoreactivity, especially against DNA. The IGHV4-34 gene is frequently utilized in chronic lymphocytic leukemia (CLL), where, typically, it shows a high load of somatic hypermutation (SHM). We have previously reported distinctive SHM patterns amongst IGHV4-34 CLL, especially for subsets with stereotyped BcR IG. However, although a large number of cases (~2000) was previously studied, since even the largest subsets account for only ~3% of CLL, meaningful conclusions could not be reached for smaller subsets. Here we revisit this issue in a series of 16,528 CLL cases and focus on IGHV4-34 expressing subsets: #4 (IGHV4-34/IGHD5-18/IGHJ6 | 156 cases, 0.9%); #11 (IGHV4-34/IGHD3-10/IGHJ4 | 16 cases, 0.1%); #16 (IGHV4-34/IGHD2-15/IGHJ6 | 41 cases, 0.25%); #29 (IGHV4-34/IGHD: unassignable/IGHJ3 | 39 cases, 0.24%); and #201 (IGHV4-34/IGHD: unassignable/IGHJ3 | 43 cases 0.26%). Focusing on codons 27-104 within the VH domain (from CDR1-IMGT to FR3-IMGT), we calculated the sequence distance between subsets and the corresponding IGHV4-34 germline sequence based on a pairwise qualitative and quantitative comparison of the respective amino acid composition. The minimum distance calculated, and hence the greatest identity, was observed between subsets #4 and #16, both concerning IgG-switched cases (IgG-CLL), which is notable given the overall rarity of IgG-CLL. In contrast, the maximum distance, implying the least identity, was between subsets #16 and #201, the latter concerning IgM/D-CLL. Extreme variations between subsets were noted in codons spanning the entire VH domain. This result is consistent with our finding of a subset-biased distribution of mutations over the VH domain. More specifically, while subsets #11, #16, #29 and #201 had a lower frequency of mutations within VH CDR1 compared to VH CDR2, the exact opposite was seen in subset #4, with 40% of mutations in VH CDR1 versus 27% in VH CDR2. In addition, subsets #4, #11, #16 and #29 had a similar distribution of mutations in VH FR2 and VH FR3, in contrast to subset #201 that showed a preference for VH FR3 over VH FR2. Consequently, we noted that certain positions were targeted in a subset-specific manner e.g. codon 28 in VH CDR1 was heavily targeted in subsets #4 (68.6%) and #16 (87.8%), with most cases carrying an acidic amino acid (AA) introduced by SHM, glycine to glutamic acid, G>E: 51.3% for subset #4 and 78% for subset #16. The high prevalence of acidic AA introduced by SHM in these subsets is notable considering the electropositive nature of their VH CDR3 (especially of subset #4), strongly recalling edited anti-DNA antibodies. Interestingly, the G>E change was identified at a much lower frequency in other IGHV4-34 subsets: 18.75% for subset #11; 2.6% for subset #29; 7% for subset #201, all of which carried electronegative VH CDR3. Further, we noted that certain positions were heavily targeted in all subsets e.g. 56-86% targeting for SHM at codon 92 in VH FR3 where serine is encoded by the agc triplet, the ”hottest of hotspots”. This result could be viewed as sequence- rather than subset-dependent and linked to the molecular features of this codon, which is supported by the low targeting of codon 93 (0-6%), also encoding serine by the tct triplet. Other positions were targeted in all subsets but at vastly different frequencies e.g. codon 64 was targeted in 37.8% in subset #4 rising to 100% in subset #29. Finally, positions heavily targeted by SHM in certain subsets were unmutated in other subsets e.g. codon 36 in VH CDR1 remained unmutated in subset #16, in contrast 76.9% of subset #29 were mutated at this position resulting in an AA change. In conclusion, we document different spectra of SHM and AA changes between stereotyped IGHV4-34 CLL subsets. The finding of subset-biased, recurrent AA changes at certain codons indicates that the respective progenitor cells may have responded in a specific manner to the selecting antigen(s), despite expressing the same IGHV gene, indicating a functional purpose for these modifications. This is exemplified by the molecular characteristics of the recurrent AA changes in subset #4, thereby offering interesting pathogenetic hints. Disclosures No relevant conflicts of interest to declare.

Abstract Background: It is now well established that the immune modulator (IMiD) drugs thalidomide (Thal), lenalidomide (Len) and pomalidomide (Pom) bind a specific pocket in the protein, cereblon (CRBN) that is required for MM cytotoxicity after IMiD treatment. Recently, we reported 46 CRBN binding proteins which were altered by Len, two of which were the transcription factors Ikaros (IKZF1) and Aiolis (IKZF3), important regulators of B and T cell development. Others had previously reported the same finding and went further by demonstrating that following binding of IMiD drugs, CRBN accumulates and accentuates the ubiquitination and subsequent proteasomal degradation of these two binding proteins. The resulting degradation and depletion of IKZF proteins has the simultaneous effect of downregulating IRF4 and MYC leading to MM cell death while simultaneously enhancing transcription of interleukin 2 and activating the immune compartment. Methods: To further explore this phenomenon and its relationship to drug sensitivity we first created two stable MM cell lines (H929IKZF1Luc, 8226IKZF1Luc) expressing an IKZF1-luciferase (luc) fusion gene and tested for sensitivity to Len alone and in combination with dexamethasone (Dex), bortezomib (Bor) or the histone deacetylase inhibitor SAHA. Next, we constructed an adenoviral vector expressing IKZF1-luc and used this to transfect 16 MM cell lines, confirmed expression and tested sensitivity to Len by MTT (Figure 1). Results: We first examined the stable cell lines and measured luc expression after exposure to all three IMiD drugs. With all IMiD drugs luc dramatically decreased in sensitive H929 cells. IKZF1 depletion was both time and dose dependent. Using this surrogate marker cell line assay, luc is most efficiently degraded by Pom which is twice as potent as Len, but a thousand times more potent than Thal (Concentration of drug required to reduce luc expression by 50%, Pom: 4.9nM, Len: 10.2 nM, and Thal: 4,795 nM). We then tested all 16 cell lines with Len 2uM for 5 hours and show a strong correlation of IKZF-luc depletion with sensitivity. Figure 1: Luc levels 5 hours after Len treatment at 2uM. We divided the cell lines into three groups: 1) Len resistant: 8226, KMS12PE, My5, SKMM2, JJN3, FR4, H112; 2) Len intermediate response: EJM, OPM2, U266, KMS18; 3) Len sensitive: H929, MM1.S, MM1.R, KMS11, XG1; Figure 1:. Luc levels 5 hours after Len treatment at 2uM. We divided the cell lines into three groups: 1) Len resistant: 8226, KMS12PE, My5, SKMM2, JJN3, FR4, H112; 2) Len intermediate response: EJM, OPM2, U266, KMS18; 3) Len sensitive: H929, MM1.S, MM1.R, KMS11, XG1; We next performed western blots on 9 MM cell lines and demonstrate that IKZF1 levels were lowest in 3 of 5 resistant MM cell lines and normal in all 4 sensitive lines studied. The cell line (FR4) with the lowest levels of IKZF1 harbors a damaging mutation of IZKF1 as well as a translocation which upregulates IRF4, an IKZF target. Of the remaining two resistant lines one has low levels of Cereblon. In one line the mechanism of IMiD resistance could not be established. Finally, we were curious about the dichotomy of the IMiD biology which seemingly has an absolute requirement for a functional proteasome for successful IMiD cytotoxicity which is at variance with clinical reports of synergy between the IMiDs and the proteasome inhibitors (PIs) Bor and carfilzomib (Car). To explore this, we treated the 8226IKZF1Luc cell line with Len alone or in combination with increasing concentrations of Bor (6 nM) or Car (40nM) and found that both totally blocked IKZF1 fusion protein degradation promoted by Len, beginning as soon as 1 hour at 100nM Bor or after 3 hours at 40nM treatment. Conversely, in low concentration of Bor (<4nM) no IKZF1 degradation blocking was observed in the Luc assay and Bor remained lethal to the MM cells. In that light with lower levels of Bor (<3nM) even varying the sequencing of MM cell exposure to the two drug classes did not block cytotoxicity. Other MM active drug Dex or SAHA, blocking the aggresome, had no significant inhibition for Len-induced IKZF1 fusion protein degradation. Conclusion: These results validate the central role for the CRBN-IKZF-IRF4 axis proteins in IMiD response and show a strong correlation of IZKF1 expression and the ability to degrade IKZF1 with sensitivity. Our data provide interesting and perhaps disconcerting biologic data suggesting that the timing and dosing of clinical use of IMiDs and PI treatment in combination should be carefully evaluated to prevent antagonism of effect but suggest in vitro that a therapeutic window exists at which proteasome inhibitors can be active without blocking IMiD activity. Disclosures Stewart: Sanofi: Consultancy; Array BioPharma: Consultancy; Bristol Myers Squibb: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Takeda Pharmaceuticals International Co.: Research Funding.

Abstract Abstract 573 Using high throughput RNA interference screening on 6,722 druggable genes we previously identified XPO1/CRM1 as one of the 50 most vulnerable targets in Multiple Myeloma (MM)1. XPO1 knockdown proved lethal in MM cell lines, but had no effect on human embryonic kidney (293) cells or lung cancer (A549) cells, showing that XPO1 is a specific myeloma vulnerability, and that myeloma cell survival is dependent upon XPO1 expression. XPO1 encodes the protein exportin 1, a nuclear transport protein that exports tumor suppressor proteins from the nucleus, where they are active, to the cytoplasm, where they become inactive. We next analyzed XPO1 in MM via gene expression profiling (GEP). XPO1 expression is up-regulated as the disease progresses: patients with active MM have a higher level of XPO1 compared to normal plasma cells (p<0.04) and to patients with monoclonal gammopathy of undetermined significance or smoldering MM (p<0.0001). The highest levels were in human MM cell lines. TC classification revealed highest levels in t(11;14) and lowest levels in t(4;14) disease. Selective inhibitors of nuclear export (SINE) compounds have recently been developed that irreversibly inhibit XPO1/CRM1 and its nuclear export function. One such inhibitor, KPT-276, decreased the viability of all 12 MM cell lines tested in vitro, as shown by MTT assay. After 72 hours of drug treatment, a median IC50 value of approximately 175 nM (range 30–1000 nM) was observed. No synergy with other commonly used anti-MM therapeutics was observed in vitro. In contrast, the drug had little effect in 8 solid tumor cell lines with the exception of the B cell lymphoma line Ramos. KPT-276 was also consistently active in inducing apoptosis against MM primary patient samples. Using an IC80 dose of KPT-276, drug-treated samples had a reduced population of cells in S phase (8%) compared to cells treated with DMSO (21%). Using the vkappa*myc transgenic MM model, KPT-276 reduced monoclonal spikes (by a mean of 56%) in all mice treated orally with 150 mg/kg dose three times per week for 4 weeks. Furthermore, KPT-276 significantly reduced tumor growth in a xenograft MM1.S mouse model. GEP was performed in the presence or absence of drug in two different MM cell lines. Two genes of probable relevance, cell division cycle 25 homolog A (CDC25A) and Bromodomain-containing protein 4 (BRD4), were dysregulated by SINE treatment. Both are involved in cell cycle control and have been linked to MYC. RT-PCR and western blotting confirm that MYC, CDC25A and BRD4 are down-regulated, as soon as six hours, after treatment with KPT-276. KPT-276 has shown marked anticancer activities against B cell malignancies in vitro and is active and tolerated in Phase I canine studies. KPT-330, a close analog of KPT-276, is currently in Phase 1 studies in human with advanced hematological and solid tumors. Disclosures: Schmidt: Karyopharm: Research Funding. McCauley:Karyopharm Therapeutics Inc: Employment. Shacham:Karyopharm Therapeutics: Employment. Kauffman:Karyopharm Therapeutics Inc: Employment. Stewart:Millenium: Consultancy, Honoraria, Research Funding; Onyx: Consultancy; Celgene: Consultancy.

Abstract Background Polycythemia vera (PV) is a clonal myeloproliferative disorder characterized by erythrocytosis, splenomegaly and a frequently burdensome symptom profile. Despite current guidelines of aspirin, phlebotomy, and selective cytoreduction, many patients have inadequately controlled PV-related symptoms and/or disease features. We performed a comparison of PV symptom burden/disease feature phenotypes to understand unmet needs in current medical management. Methods Data was collected prospectively amongst an international cohort of PV patients including symptom burden, demographics, and disease features. Subgroups were identified who had previously failed hydroxyurea (PV-HU), required ongoing phlebotomy (PV-P), had palpable splenomegaly (PV-S), or had all 3 features (PV-HUPS). Control groups were derived from the remaining PV patients lacking the specified subgroup trait; patients in whom the trait status was unknown were excluded from each respective control group. All participants completed the MPN specific symptom burden questionnaire (MPN-SAF TSS (MPN-10 – Table 1)) and had no prior history of splenectomy. Surveyed symptoms on the MPN-10 included the patient's perceptions of common MPN-related symptoms and overall quality of life (QOL) on a 0 (absent) to 10 (worst imaginable) scale. PV risk scores were calculated using the 2013 criteria (Leukemia 2013). Comparison of symptoms between groups employed t-tests. Results Patient Demographics and Disease Features Between Phenotypic Groups A total of 1334 PV patients completed the MPN-10, and were assigned to categories of PV-HU (499 [37%]), PV-P (646 [48%]), PV-S (369, [28%]), and PV-HUPS (148 [12%]). The demographics between these groups were similar (comparable age (median range 60-63), PV risk scores (mean risk range: Low 16.4-23.7%; Intermediate 31.4%-36.6%; High 42.8%-47%). Mean hemoglobin was similar among PV subgroups (range 14.4-14.9); PV-HUPS had a higher mean WBC count (20.3 g/dL vs. 8.8-11.8 g/dL) and platelet count (703.5 x 10(9)/L vs. 327.5-462.8 x 10(9)/L), and disease duration (11.5 years vs. 6.4-8.8 years). Prior thrombosis was most common in PV-S patients (28.5% vs. 21.8-25.2%) and prior hemorrhage was most common in PV-HUPS patients (23.8% vs. 13.7-15.8%). Symptom Burden The MPN-10 scores of each problematic PV phenotype (HU, P, S, HUPS) were compared to the remainder of the PV cohort lacking the trait (PV-control; Table 1). Both individual symptom scores and TSS were highest for PV-HUPS patients (mean TSS 32.5 vs. 27.7-29.2). All problematic PV subgroups demonstrated significant differences for individual symptoms and TSS compared to PV-control. Comparing "problematic" subgroup responses, PV-HU patients described more inactivity whereas PV-S patients described more early satiety and pruritus. No statistical differences were noted in PV-HU, PV-P and PV-HUPS patient responses to MPN-10 items of "fever" and "weight loss". Discussion PV patients who have either failed HU, are undergoing phlebotomy and/or have splenomegaly exhibit moderate to severe symptomatology and demonstrate unmet medical need for management. As evidenced in this study, considerable overlap in symptomatology exists in PV-HU, PV-P, PV-S and PV-HUPS. Current randomized trials of JAK inhibitors have demonstrated benefits in a PV-HUPS phenotype. This data suggests that PV patients with any evidence of inadequate control (PV-HU, P, or S) have similarly unmet needs and may be candidates for clinical trials, intensification of medical therapy or perhaps JAK inhibitor therapy. Disclosures Kiladjian: Shire Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Zweegman:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees, Research Funding. Besses:Shire Pharmaceuticals: honoraria for educational lectures Other. Birgegard:Shire Pharmaceuticals: Consultancy, Honoraria, Research Funding. Etienne:Novartis, BMS, Pfizer, Ariad: Honoraria. Roy:Merck: Peg-Interferon provided for academic clinical trial in CML Other. te Boekhorst:Novartis: Consultancy. Griesshammer:Novartis: Honoraria; Shire: Honoraria; Sanofi: Honoraria; Amgen: Honoraria; Roche: Honoraria. Mesa:Incyte Corporation, CTI, NPS Pharma, Inc., Gilead Science Inc., Celgene: Research Funding.

Abstract Abstract 194 Background: Immunomodulatory drugs (IMiDs) are key components of treatment for hematologic malignancies, especially multiple myeloma (MM). Recently, we demonstrated that CRBN expression is the major mediator of IMiD action operating at least in part via interferon regulatory factor 4 (IRF4), however the clinical significance of this finding remains unclear. Methods: To better understand clinical impact, we retrospectively reviewed 148 MM patients whose tumor cells were tested for CRBN expression by Gene Expression Profiling (GEP) prior to treatment with an IMiD containing therapy. Results: GEP studies show no significant differences in CRBN expression between MGUS, smoldering MM (SMM), untreated symptomatic MM and normal plasma cells. However, differences were observed between MM cell lines of varying drug sensitivity to IMiDs and between other B-cell Neoplasia (eg low grade lymphoma has higher levels). Within the genetic subtypes of MM, levels were significantly higher for hyperdiploid patients (median 1.26) as opposed to significantly lower levels for TC class D2 (median 0.76) and average for the 4p16 (median 0.97). We next screened the University of Arkansas Medical School (UAMS) GEP database of MM patients treated with combination therapies and did not find significant correlation between CRBN expression and survival in this multi-agent regimen. We then focused on patients that received only single agent IMiD therapy with low dose dexamethasone. Review of the twelve lowest expressing patients demonstrated a lack of response to IMiDs in any patient. Finally we analyzed 53 relapsed or relapsed/refractory patients treated homogeneously in a study with pomalidomide 2–4mg daily and weekly dexamethasone 40mg. CRBN levels were assessed prior to therapy initiation. Response rates varied significantly based on gene expression level. The percentage of patients that demonstrated at least a partial response was 0% for CRBN <0.81, 19% for CRBN expression of 0.81–0.90, and 33% for CBN expression >0.9. Significant differences in PFS (3.0 months vs. 8.9 months, p = 0.0006) and in OS (9.1 months vs. 27.2 months, p = 0.01) were observed when the lowest quartile of CRBN expression was compared to the top three quartiles. Values used for the cut offs are as follows: (25%: 0.889687; 50%: 1.026542, 75%: 1.211133). While this study demonstrates a positive correlation between CRBN expression and response to pomalidomide and dexamethasone, an important caveat with respect to PFS and OS is that CRBN mRNA level is primarily a reflection of the number of copies of CRBN. Since focal deletions are uncommon, this mostly reflects chromosome 3p copy number. Since trisomy 3 is common in hyperdiploid, good prognosis disease, CRBN not only is required for IMiD function but higher levels also serve as a surrogate for low risk disease. Optimal gene expression cut offs for survival were determined using the Contal and O'Quigley method. The optimal cut point for PFS was 1.18443 and for OS was 1.17816. Conclusion: In summary, this study demonstrates, for the first time, a clinical correlation between CRBN expression and response to IMiD and dexamethasone therapy. CRBN expression is also predictive of survival outcomes and when quantified prior to therapy could potentially be utilized as a predictive biomarker for response to an IMiD based treatment. Disclosures: Stewart: Celgene: Consultancy, Honoraria.

INTRODUCTION: Reduced gastric accommodation (GA) or accelerated or delayed gastric emptying (GE) contributes to pathophysiology in functional dyspepsia (FD). Secretin is an endogenous hormone secreted postprandially from the duodenal mucosa. Our objective was to determine the effects of secretin in human gastric motor functions and satiation in health and FD. METHODS: We conducted a double-blind, randomized, placebo-controlled, cross-over trial in 10 healthy participants and 10 patients with FD by Rome IV criteria. Subjects were randomized to IV secretin or normal saline with a 1-4 week washout period. We measured GA using validated 99m Tc-single photon emission computed tomography with a standardized 300 mL meal of 111 In radiolabeled Ensure®. We measured GE using scintigraphy of the same meal and symptoms 30 minutes post meal based on 100 mm visualized analog scale (VAS). To measure volume to fullness (VTF) and maximum tolerated volume (MTV), we performed Ensure® nutrient drink test (NDT) and recorded symptoms 30 min post-MTV. Wilcoxon Signed-Rank Test was used for comparison within healthy and FD groups and ANCOVA modeling was used for intention to treat comparison between groups, adjusting for age, sex, and treatment arm (secretin vs. placebo). Study drug was provided by ChiroClin, Inc. RESULTS: The median age for healthy volunteers (HV) was 45.0 years [IQR: 38.0, 49.0 (80% female)] and for FD was 50.5 years [42.0, 55.0 (70% female)]. There was no statistical difference in either group for secretin vs. placebo for GA. Secretin delayed GE in both HV and FD (Table 1). There was decrease in GE for secretin vs. placebo in HV at 20 minutes [-10% (-13, -7), P = 0.008] and 30 minutes [-11% (-16, -4), P = 0.004]. This finding was also seen in the FD group for GE at 25 minutes [-5% (-9, 0), P = 0.047] and 30 minutes [-8% (-9, 0), P = 0.03]. There were no statistically significant differences between treatment arms for VTF or MTV in either HV or FD. On ANCOVA analysis, there were statistically significant increases in nausea at 30 minutes ( P = 0.0016) and fullness at 30 minutes ( P = 0.0002) for secretin vs. placebo in FD compared to HV. CONCLUSION: Secretin delayed GE in both healthy volunteers and FD without significantly altering GA, VTF, or MTV. Secretin receptor stimulation deserves further study in FD patients with accelerated GE.

INTRODUCTION: Increasing rates of obesity have led to increased numbers of bariatric surgeries performed world-wide. However, some patients do not achieve significant weight loss or develop weight regain following these procedures. Other than estimating the size of the gastric remnant at endoscopy or transaxial imaging, there are limited approaches to quantitate the function of the post-surgical stomach in order to evaluate the disparate weight patterns, or to develop strategy for future treatments, e.g., pharmacotherapy or endoscopic intervention. We hypothesize that altered gastric function in the pre- and post-surgical periods may offer an explanation. Studies performed thus far are difficult to interpret due to heterogeneity in approaches to diagnostic evaluation. The aims of this project were: to assess the feasibility of a new protocol for simultaneous evaluation of gastric accommodation and gastric emptying in the post-bariatric state; and to report normative values in healthy volunteers. METHODS: Methods: We utilized single photon emission computed tomography (SPECT) and gamma scintigraphy to concurrently study postprandial gastric accommodation responses and gastric emptying rates of a limited size meal designed for subsequent use in post-bariatric patients. The standard meal consisted of 1 egg and 1 extra egg yolk scrambled with 111 Indium-activated charcoal (∼130kcal, 9.5g fat) and 120mL 2% milk (130kcal, 4.4g fat). Gastric accommodation was measured using 99m Technetium-SPECT. SPECT imaging was obtained concomitant with gastric emptying of the 111 In-labeled meal. Anterior and posterior scans of the abdomen were obtained for estimating gastric emptying parameters every 15 minute until 90 minutes, and then in 30-minute intervals until 240 minutes or complete emptying. RESULTS: Data on 28/30 healthy volunteers (35.7% men; 67% Caucasian) with completed studies to date are shown in the Table 1 (data presented as mean ± standard deviation). Gastric emptying proportion at 1, 2, and 4 hours, T 1/2 , and gastric volumes including accommodation are graphically depicted in Figures 1 and 2, respectively. CONCLUSION: Discussion: This study has demonstrated feasibility of simultaneous measurement of gastric emptying and accommodation and provides normal values; this sets the stage for future baseline and post-operative scans on patients undergoing sleeve gastrectomy.

INTRODUCTION: Over-the-scope clips (OTSC) are used for closure of fistulas, leaks, and acute perforations, and for GI bleeding. Adverse events include perforation, migration, and ulceration. Little is know about the natural history of OTSCs and no data addressing the longevity of clips is available. We present an interim analysis of our center’s experience with OTSC focusing on natural history. METHODS: OTSCs used from 1/1/2011 to 1/1/2019 were compiled and retrospective chart review undertaken. Primary endpoint was clip retention time (time when the clip was placed to time the clip was last seen or was physically removed). Secondary endpoints were rate of complications and factors that influence clip retention time and clinical success. Cox proportional hazards were used to evaluate variables impacting clip retention. Univariate regression was used to assess potential risk factors for adverse events. RESULTS: A total of 358 OTSC were placed in 299 patients (55.8% male, n = 184) with mean age 64 + 15.3 years. Procedures and indications presented in Table 1. Clip placement was clinically successful in 81% of cases (N = 265). Median time to clip loss as assessed by Kaplan-Meier curve was 267 days (95% CI 196-406) (Figure 1). Adverse events occurred in 34 clip placements (10.7%) and included bleeding (n = 8, 24.2%), perforation (n = 5, 15.2%), ulceration (n = 3, 9.1%), migration (n = 15, 45.5%), and infection (n = 1, 3.0%). Univariate analysis (Table 2) revealed that age, gender, type of clip used (there are 3 types of OTSC), and performing endoscopist did not impact clip retention rate. A size 14 clip had marginally higher rates of retention compared to others. Clips placed in the rectum or esophagus were lost earlier compared to those in the small/large intestine and stomach. Clips placed for fistulas and those associated with adverse event were associated with earlier clip loss. In evaluation of clinical success, clips placed for fistulas had a relative risk of clinical failure of 2.08 (95% CI 1.29-3.36) compared to all other indications. CONCLUSION: OTSCs are retained for a median of 8.9 months with clip location and indication for placement being key factors in time to clip loss. Clips used for fistula closure were more likely to be lost compared to those placed for other indications, less likely to be clinically successful, and more likely to cause a complication. These data help guide decision-making when considering OTSC use across clinical indications.

INTRODUCTION: Double balloon enteroscopy (DBE) is an important tool for evaluation of obscure GI bleeding but is a limited resource given time and expertise required. Patient selection is important to help optimize diagnostic yield and subsequent successful management of small bowel bleeding. To maximize the efficiency of DBE performed, our endoscopy group established a screening protocol (Figure) prior to approval of any procedure. We developed a quality improvement project to assess the efficacy of this screening protocol and to evaluate which components of screening were most predictive for procedural success. METHODS: A retrospective chart review was performed on all patients who underwent anterograde or retrograde double balloon enteroscopy for suspected GI bleeding from January 2016 to December 2017. Our screening protocol was implemented on February 1 st , 2017. Data was obtained on patient demographics, clinical presentation, laboratory evaluation, and prior investigation for bleeding evaluation. Endoscopy outcomes were separated into procedural success, defined as lesion identified, and clinical success, defined as resolution of bleeding. Success rates were compared pre and post intervention. Regression analysis was performed to evaluate which components best predicted a successful procedure. RESULTS: We reviewed 114 DBE procedures in 89 patients, 53.5% male (n = 61) with a mean age of 62.8 + 13.3 years. Of these, 86% (n = 98) were performed prior to initiation of the screening protocol. Overall, there was no significant difference in procedural success pre and post intervention as defined by presence of recurrent bleeding, persistent anemia, or transfusion need (Table 1). On univariate analysis of clinical success, defined as lack of recurrent bleeding, gender, anticoagulation use, and presence of lesion on CE were significant (Table 2). Identification and intervention on a lesion during the balloon endoscopy did not impact future anemia, bleeding, or transfusion requirements. CONCLUSION: The patient screening protocol was successful in decreasing the number of procedures performed but did not improve our lesion detection rate on endoscopy and did not improve clinical outcomes as measured by rebleeding. Patients on anticoagulation and those who had prior lesions identified on capsule endoscopy had higher odds of rebleeding, indicating clinical failure. This data may help modify patient selection to maximize success of DBE procedures in the future.

INTRODUCTION: Loey Dietz syndrome (LDS) is an autosomal dominant disorder caused by a mutation in TGFBR1 - or TGFBR2. LDS is characterized by distinctive facies, tortuous arteries and aortic aneurysms predisposition to eosinophilic allergic disorders including eosinophilic esophagitis and gastritis, and other systemic findings including inflammatory bowel disease. Patients with vascular Ehlers Danlos Syndrome (vEDS) have deficiency in type III collagen and have similar vascular laxity and concomitant GI manifestations. This connective tissue vulnerability contributes to increased post-operative wound dehiscence and development of hernias. Our aim was to summarize abdominal wall and GI tract manifestations in these two rare vascular disorders at a tertiary referral center. METHODS: Data were collected via Advanced Cohort Explorer (ACE) application at Mayo Clinic. A chart review was undertaken on patients with a confirmed diagnosis of vEDS or LDS seen at Mayo Clinic in Rochester from 1994 to 2018. Diagnoses were confirmed by genetic testing and/or clinical review through the specialized medical genetics clinic. Information was extracted on vascular complications of disease, prevalence of abdominal hernias, and gastrointestinal symptoms. The study was reviewed and exempted by the Mayo Clinic IRB. RESULTS: We identified and reviewed records of 50 vEDS and 13 LDS patients; data are summarized in Tables 1 and 2. Patients were similar in age at diagnosis and gender distribution. Hernias were present in similar proportions of patients with vEDS and LDS, although ventral hernias were more frequent and the hernias were more likely to be post-operative in vEDS than in LDS. LDS patients had more aneurysms (58% vEDS vs. 76.9% LDS, P = 0.02) with higher proportion requiring arterial repair (32.7% vEDS vs. 69.2% LDS, P = 0.03). Co-morbidities more prevalent in LDS than vEDS were autonomic dysfunction, psychopathology and allergy. We did not note increase in symptoms suggestive of eosinophilic esophagitis/gastritis in the LDS patients. GI symptoms were prevalent in both disorders and largely similar, except for diarrhea and constipation which were both significantly more prevalent in LDS patients. CONCLUSION/DISCUSSION: While vEDS and LDS are both connective tissue disorders with propensity for GI symptoms, abdominal hernias and aneurysm formation, the risk of arterial rupture and co-morbidity of autonomic dysfunction, psychopathology and allergy are greater in LDS than vEDS.