A156 OUTCOMES FOLLOWING ENDOSCOPIC RESECTION OF GASTRIC NEUROENDOCRINE TUMOURS FROM A TERTIARY-CARE ACADEMIC CENTRE

Background

Gastric neuroendocrine tumours (G-NET) are rare cancers derived from neuroendocrine cells of the stomach. A steady increase in the incidence of these tumours has been observed. Current treatment and surveillance strategies are guided by various tumour characteristics including size, grade, and depth of invasion. There exists conflicting evidence, however, on the rates of recurrence from positive resection margins following primary endoscopic resection. Thus, it remains uncertain whether complete endoscopic resection (R0) of these indolent tumours is clinically significant and whether follow-up endoscopic or surgical intervention is justified.

Purpose

Our aim is to characterize current management patterns and clinical outcomes in patients undergoing endoscopic resection of G-NETs.

Method

We conducted a retrospective, single-centre cohort study at The Centre for Advanced Therapeutic Endoscopy and Endoscopic Oncology at St. Michael’s Hospital, Toronto, Ontario. Consecutive patients over the age of 18 who underwent endoscopic resection of histologically proven G-NETs between 2011 and 2020 were included. Data on patient, endoscopic, and tumour characteristics were collected through electronic chart review. Descriptive statistics were conducted for data analysis.

Result(s)

A total of 155 foregut neuroendocrine tumours were endoscopically resected during the study period, of which 108 were identified as G-NETs. 95.3% were classified as Type I. Mean tumour size was 8.93 ± 5.27 mm. Cap-assisted EMR was performed most frequently (n=51), followed by conventional EMR (n=35). ESD was performed in eight cases. Seven intra-procedural perforations occurred, of which all were closed endoscopically. One patient experienced post-procedural perforation requiring ICU and surgery. Positive resection margins (R1) were found in 25% of cases (n=27), of which 78% were assessed at surveillance endoscopy 1 (SE1). Six patients with R1 margins were referred for surgical evaluation and four were lost to follow-up. 78% of all resected G-NETs were followed at SE1 with a median interval of 196 days (range, 23 to 3373). SE1 recurrence rate at the primary resection site was 14% (n=12), of which two were from routine scar biopsies in the absence of endoscopically identifiable recurrence. All visible recurrences at these sites (n=10) were managed with repeat endoscopic resection. Patient and tumour characteristics in the evaluation of G-NET recurrence are presented in Table I.

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Conclusion(s)

G-NET recurrence occurs in less than 15% of patients at surveillance endoscopy following endoscopic resection in spite of a predictably higher R1 resection rate. Patient, endoscopic, and tumour factors including method of resection and margin status do not appear to impact the development of early recurrence. Given the indolent nature of these tumours, patients with positive resection margins can be followed conservatively. Further investigation is warranted to determine the optimal duration and surveillance strategy for these patients.

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None

Disclosure of Interest

None Declared

A155 OUTCOMES FOLLOWING ENDOSCOPIC RESECTION OF DUODENAL NEUROENDOCRINE TUMOURS FROM A TERTIARY-CARE ACADEMIC CENTRE

Background

Duodenal neuroendocrine tumours (D-NET) are rare cancers derived from neuroendocrine cells of the duodenum. A steady increase in the incidence of these tumours has been observed. Current treatment and surveillance strategies are guided by various tumour characteristics including size, grade, and depth of invasion. There exists conflicting evidence, however, on the rates of recurrence after positive resection margins following endoscopic resection. Thus, it remains uncertain whether complete endoscopic resection (R0) of these indolent tumours is clinically significant and whether follow-up endoscopic or surgical intervention is justified.

Purpose

Our aim is to characterize endoscopic management and clinical outcomes in patients undergoing endoscopic resection of D-NETs.

Method

We conducted a retrospective, single-centre cohort study at The Centre for Advanced Therapeutic Endoscopy and Endoscopic Oncology at St. Michael’s Hospital, Toronto, Ontario. Consecutive patients over the age of 18 who underwent endoscopic resection of histologically proven D-NETs between 2011 and 2020 were included. Data on patient, endoscopic, and tumour characteristics were collected through electronic chart review. Descriptive statistics were conducted for data analysis.

Result(s)

A total of 155 foregut neuroendocrine tumours (NET) were endoscopically resected amongst 96 patients during the study period. 47 of these were histologically identified as D-NETs. Mean tumour size was 9.88 ± 6.86 mm. Conventional endoscopic mucosal resection (EMR) was performed most frequently (55%, n=26/47), followed by cap-assisted EMR (30%, n=14/47). Hybrid endoscopic submucosal dissection (ESD)/EMR was performed in one case. A total of two intra-procedural perforations occurred, both of which were successfully closed endoscopically. One patient with a peri-ampullary D-NET experienced significant intra-procedural bleeding requiring Hemospray® and subsequent endotracheal intubation resulting in a brief hospitalization. 57% of all resected D-NETs were followed at surveillance endoscopy 1 (SE1) at a median interval of 199 days (range, 84 to 830). Positive resection margins (R1) were found in 26 cases (55%), of which 16 were assessed at SE1 while nine were lost to follow-up. One patient with R1 margins was electively treated with APC at SE1. Tumour recurrence at SE1 occurred in only two patients.

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Conclusion(s)

D-NET recurrence is found in less than 5% of patients at surveillance endoscopy following endoscopic resection in spite of a high R1 resection rate. Given this indolent nature of these tumours, our study suggests that patients with positive resection margins can be followed conservatively with surveillance endoscopy. Further investigation is warranted to determine the optimal duration and surveillance strategy for these patients.

Please acknowledge all funding agencies by checking the applicable boxes below

CAG

Disclosure of Interest

None Declared

Evaluating program planning using an equity framework

To plan for an expansion of healthcare services in newly developed neighbourhoods, a planning initiative was conducted to better understand the needs of the population. Ensuring equity of care was identified as a priority for this initiative. To evaluate how closely the planning adhered to the principles of health equity, we applied Ontario Health's Equity, Inclusion, Diversity, and Anti-Racism Framework to determine which areas of action were successfully addressed, and which areas of action require further focus. The framework contains 11 components, each delineating a key area of action. Using this framework helped identify areas where the principles of equity were well addressed, as well as pointing to additional areas where further efforts are required. Healthcare organizations must take a leadership role in advancing health equity by planning, delivering, improving, and advocating for the services and systematic changes that will allow its local community members to realize their highest attainable standard of health. Using such a framework can help develop strategic approaches to advancing equity.

222 Robotic Surgery: Public Perceptions and Current Misconceptions

Aim

While surgeons and robotic companies are key stakeholders involved in the adoption of Robotic Surgery (RS), the public's role is often overlooked. However, given that patients hold ultimate power over their healthcare decisions, public acceptance of RS is crucial. This study aims to identify public understanding, opinions and misconceptions on RS and present solutions to facilitate its wider integration.

Method

An online questionnaire distributed via social media platforms between February and May 2021 identified the views of UK adults on RS. The data was evaluated using thematic analysis, descriptive statistics, and statistical analysis. Statistical differences in age, gender, education level, and presence in the medical field were also sought.

Results

263 responses were obtained, with 216 (82.1%) analysed. Demographic differences provided significantly different results. Participants were relatively uninformed about RS, with a median knowledge score of 4.00(2.00–6.00) on a 10-point likert scale. Fears surrounding increased risk, reduced precision and technological failure were identified, alongside misconceptions on what RS entails, including it being autonomous. However, providing factual information in the survey about RS statistically increased participant comfort (p=<0.0001). Most (61.8%) participants believed robot manufacturers were responsible for malfunctions, but doctors were held accountable more by older, less educated, and non-medical participants.

Conclusions

This study highlights the role of negative and inaccurate public perceptions surrounding RS in impeding its widespread adoption. Greater emphasis must be placed on patient education in RS to mitigate misconceptions and ensure greater diffusion of its benefits

219 The Opportunities and Challenges of Robotic Surgery: A Surgeon and Robotic Company Perspective

Introduction

As an increasing number of specialties have begun to adopt robotic surgery (RS), its prevalence within the NHS is continually rising. This study aims to establish stakeholders’ opinions on the opportunities and challenges of the widespread adoption of RS.

Method

Participants were recruited through social media platforms such as LinkedIn or via university affiliations and current RS research. Semi-structured interviews of eight surgeons and five company representatives were conducted online. Transcripts were analysed to formulate themes surrounding the opportunities and challenges of RS.

Results

This study identified six common themes amongst shareholders: Perspective, Ethics, Impact of Robotics, Training, Adoption and Finances. The success rates and quality of results offered by RS make it a recognised future surgical staple amongst interviewees. However, the technology remains a contentious subject amongst surgeons, with many doubting whether the benefits outweigh the costs associated with implementation. Such reservations are further exacerbated by the absence of a formal training pathway. National guidelines are necessary to embed RS within the NHS infrastructure, allowing greater standardisation for patients and surgeons. The importance of patient education to address misconceptions was emphasised. Despite current high costs, robotic technology is forecasted to become cheaper with greater use and increased market competition. Interviewees stressed that responsibility for errors lies with the surgeon, but with the manufacturer for instrument malfunctions.

Conclusions

This study highlights stakeholders’ views on the opportunities and challenges of RS. The identified themes should form the basis of the proposed recommendations to facilitate a more widespread adoption of RS.

A74 INCREASING RATES OF CT IMAGING IN THE EMERGENCY DEPARTMENT AMONG PATIENTS WITH INFLAMMATORY BOWEL DISEASE

Background

Computed tomography (CT) imaging of the abdomen is often performed in the emergency department (ED) to exclude urgent pathology in patients with Inflammatory Bowel Disease (IBD). However, concerns over excessive radiation exposure from repeated use have led to expert consensus guidelines advising against CT imaging unless there is suspicion of complications (obstruction, perforation, abscess) or a non-IBD cause for symptoms.

Aims

Our study aimed to determine trends in abdominal CT utilization and findings among patients with IBD in the ED.

Methods

We performed a retrospective cohort study between 01/01/2009 and 31/12/2018 at a single academic center. We identified ED encounters for adults (age ≥17 years) with a pre-existing diagnosis of IBD from our institutional database and determined the proportion resulting in an abdominal CT scan within 72 hours of presentation. IBD subtypes were classified based on ICD-10 claims: K50.90* for Crohn’s disease (CD), K51.90* for Ulcerative colitis (UC) and IBD undifferentiated (IBDU) for patients with both claims. A time trend analysis was performed using a generalized linear model that assumed a Poisson distribution. CT scans were classified according to the dominant imaging finding. For this part we excluded studies performed within 1-month of surgery or those re-assessing a known abscess or malignancy.

Results

A total of 14783 encounters were identified. Among these encounters 3000 CT scans were performed: 2000 for patients with CD (21.9%), 652 for UC (16.5%) and 348 for IBDU (20.4%). The rates of CT utilization significantly increased by 2.7% (95% CI, 1.2–4.3; p=0.0004) in patients with CD, by 4.2% (95% CI, 1.7–6.7; p=0.0009) in patients with UC and by 6.3% in patients with IBDU (95% CI, 2.5–10.0; p=0.0011). Among the eligible CT scans performed for CD, the following dominant findings were reported: normal (25%), inflammation (23%), obstruction (23%), penetrating (18%) and unrelated to IBD (8.6%). In contrast, the following findings for patients with UC were reported: normal (20%), inflammation (39%), obstructive (19%), penetrating (8%) and unrelated to IBD (15%).

Conclusions

In this single center study, a steady increase in CT utilization in the ED was observed in patients with IBD. Interestingly, only a small proportion of the CT scans demonstrated urgent findings. Future studies are required to determine the factors that contribute to the ongoing increase in CT utilization in this patient population.

Funding Agencies

None

Deletion of immune evasion genes provides an effective vaccine design for tumor-associated herpesviruses

Vaccines based on live attenuated viruses often induce broad, multifaceted immune responses. However, they also usually sacrifice immunogenicity for attenuation. It is particularly difficult to elicit an effective vaccine for herpesviruses due to an armament of immune evasion genes and a latent phase. Here, to overcome the limitation of attenuation, we developed a rational herpesvirus vaccine in which viral immune evasion genes were deleted to enhance immunogenicity while also attaining safety. To test this vaccine strategy, we utilized murine gammaherpesvirus-68 (MHV-68) as a proof-of-concept model for the cancer-associated human γ-herpesviruses, Epstein-Barr virus and Kaposi sarcoma-associated herpesvirus. We engineered a recombinant MHV-68 virus by targeted inactivation of viral antagonists of type I interferon (IFN-I) pathway and deletion of the latency locus responsible for persistent infection. This recombinant virus is highly attenuated with no measurable capacity for replication, latency, or persistence in immunocompetent hosts. It stimulates robust innate immunity, differentiates virus-specific memory T cells, and elicits neutralizing antibodies. A single vaccination affords durable protection that blocks the establishment of latency following challenge with the wild type MHV-68 for at least six months post-vaccination. These results provide a framework for effective vaccination against cancer-associated herpesviruses through the elimination of latency and key immune evasion mechanisms from the pathogen.

AB0626 IMATINIB FOR THE TREATMENT OF SYSTEMIC SCLEROSIS: RATIONALE, CLINICAL EVIDENCE AND FUTURE DEVELOPMENT

Background:

Systemic sclerosis (SSc) is a chronic disorder of connective tissue affecting the skin and internal organs. The molecular mechanisms behind SSc are not entirely understood, but recent advances highlight key signalling pathways1(see Figure 1). Fibrosis disrupts tissue architecture resulting in organ dysfunction. This causes significant morbidity and mortality1, therefore there is a clear need for identifying efficacious antifibrotic treatment.

Imatinib is a tyrosine kinase inhibitor with established use in some malignancies, and existing evidence that it can treat SSc2.

Objectives:

The aim of this literature review is to summarise the current evidence and future developments of imatinib as antifibrotic treatment in SSc.

Methods:

PubMed headings “systemic sclerosis”, “scleroderma”, “imatinib” and synonyms were used. See Figure 2.

Results:

Lead author and yearStudy designPopulationIntervention (imatinib dose given daily)ResultsHinchcliff ME. 2016Case study1 female (F) with an 8-month history of diffuse cutaneous systemic sclerosis (dcSSc)400mgSevere adverse events (AEs)Pope J. 2014Early phase proof of concept trial10 with dcSSc.9 given 400mg, 1 placeboPoor drug tolerabilityPrey S. 2012Double blind RCT28 with SSc15 given 400mg, 13 placeboNo improvementKhanna D. 2011Phase I/IIa pilot trial20 with SScUp to 600mgAEs presentPope J. 2011Double blind RCT10 with SSc.9 given 400mg, 1 placeboNo improvement, AEs presentGordon J. 2014Open label, single arm, extension phase clinical trial17 with average disease duration of 3.5 years100-400mg↓ modified Rodnan skin score (mRSS)Fraticelli P. 2014Phase II pilot trial30 with SSc200mg↑ lung functionGuo L. 2012Case series6 F, Chinese pts with SSc200mg↓ mRSS and ↑ lung functionDivekar AA. 2011Single centre, open-label study15 with SSc100mg up to 600mg/day↑ lung functionSpiera RF. 20111-year, phase IIa, single-arm, open-label clinical trial30 with dcSSc400mg↓ mRSS and ↑ lung functionFreyhaus H. 2009Case report58yo F400mg↑ lung functionChung L. 2009Case report2 with early dcSSc200mg↓ mRSS and ↑ lung functionVan Daele PL. 2008Case report69yo F400mg↓ mRSS and ↑ lung functionP. P. Sfikakis. 2008Case report24yo F400mg↓ mRSS and ↑ lung function

9 studies showed imatinib had positive efficacy in the treatment of SSc. 5 showed no improvement or adverse effects.

Conclusion:

Overall, current evidence suggests that imatinib can be a useful drug to improve manifestations of SSc, for some. Despite inconclusive evidence, a dose-dependent relationship seems to exist for imatinib toxicities, with more research needed to ascertain a safe dose.

Gene expression profiles may distinguish patients that can benefit from imatinib3. Also, Notch signalling could be exploited to increase imatinib uptake into fibroblasts, thereby increasing efficacy4.

References:

[1]Pattanaik D et al. Pathogenesis of Systemic Sclerosis. Frontiers in Immunology. 2015;6: 272

[2]Distler JHW et al. Tyrosine kinase inhibitors for the treatment of fibrotic diseases such as systemic sclerosis: towards molecular targeted therapies. Annals of the Rheumatic Diseases. 2010;69: 48-51

[3]Chung L et al. Molecular framework for response to imatinib mesylate in systemic sclerosis. Arthritis and Rheumatology. 2009 Feb;60(2):584-91

[4]Harrach S et al. Notch Signaling Activity Determines Uptake and Biological Effect of Imatinib in Systemic Sclerosis Dermal Fibroblasts. Journal of Investigative Dermatology. 2019; 139(2):439-4475

Acknowledgments:

Skin Research Institute of Singapore

Disclosure of Interests:

None declared

Gamma Herpesvirus manipulates HVEM regulated IL-1β pathway to evade immune responses

The herpes virus entry mediator (HVEM) a member of the TNFR superfamily, is a key immunoregulator with both proinflammatory and inhibitory signaling functions. Both α and β-herpes viruses exploit HVEM to establish persistent infections, however little is known about whether the oncogenic γ-herpesviruses modulate HVEM. Here, we investigate the role of HVEM in a mouse model of γ-herpesvirus (MHV68) infection. Control C57BL/6 and HVEM-deficient (Tnfrsf14−/−) mice were intranasally infected with MHV68. We found that virus replication in the lungs of Tnfrsf14−/− mice increased significantly indicating HVEM expression is required to control MHV68 infection. We found that alveolar macrophages were drastically reduced in Tnfrsf14−/− mice compared to C57/BL6 controls suggesting their survival requires HVEM signaling. Importantly, we showed that IL-1β levels in the lungs of MHV68 infected Tnfrsf14−/−mice were significantly higher than C57BL/6 controls. Bone marrow-derived macrophage from Tnfrsf14−/− showed that HVEM is necessary to prevent IL-1β production in response to inflammasome activator. Antibodies that block IL-1R or IL-1β drastically increased the viral load in the lungs suggested that IL-1β is necessary to control viral replication. Taken together, our results highlight the role for HVEM in innate immune response evasion of MHV68 that could involve the inflammasome.

Genome-wide identification of interferon-sensitive mutations enables influenza vaccine design

In conventional attenuated viral vaccines, immunogenicity is often suboptimal. Here we present a systematic approach for vaccine development that eliminates interferon (IFN)-modulating functions genome-wide while maintaining virus replication fitness. We applied a quantitative high-throughput genomics system to influenza A virus that simultaneously measured the replication fitness and IFN sensitivity of mutations across the entire genome. By incorporating eight IFN-sensitive mutations, we generated a hyper-interferon-sensitive (HIS) virus as a vaccine candidate. HIS virus is highly attenuated in IFN-competent hosts but able to induce transient IFN responses, elicits robust humoral and cellular immune responses, and provides protection against homologous and heterologous viral challenges. Our approach, which attenuates the virus and promotes immune responses concurrently, is broadly applicable for vaccine development against other pathogens.

Limiting Cholesterol Biosynthetic Flux Spontaneously Engages Type I IFN Signaling

Cellular lipid requirements are achieved through a combination of biosynthesis and import programs. Using isotope tracer analysis, we show that type I interferon (IFN) signaling shifts the balance of these programs by decreasing synthesis and increasing import of cholesterol and long chain fatty acids. Genetically enforcing this metabolic shift in macrophages is sufficient to render mice resistant to viral challenge, demonstrating the importance of reprogramming the balance of these two metabolic pathways in vivo. Unexpectedly, mechanistic studies reveal that limiting flux through the cholesterol biosynthetic pathway spontaneously engages a type I IFN response in a STING-dependent manner. The upregulation of type I IFNs was traced to a decrease in the pool size of synthesized cholesterol and could be inhibited by replenishing cells with free cholesterol. Taken together, these studies delineate a metabolic-inflammatory circuit that links perturbations in cholesterol biosynthesis with activation of innate immunity.

Attraction of the redbay ambrosia beetle, Xyleborus glabratus, to avocado, lychee, and essential oil Lures

The redbay ambrosia beetle, Xyleborus glabratus Eichhoff, is an exotic wood-boring insect that vectors the mycopathogen responsible for laurel wilt, a lethal vascular disease of trees in the Lauraceae. High mortality has occurred in native Persea species in the southeastern U.S., and the vector-pathogen complex poses an imminent threat to the production of commercial avocado, P. americana, in south Florida. There is a critical need for effective attractants to detect, monitor, and control this invasive pest. This study combined field tests and laboratory bioassays to evaluate the response of female X. glabratus to host-based volatiles from wood of avocado (cultivars of West Indian, Guatemalan, and Mexican races); from wood of lychee (Litchi chinensis, a presumed non-host that is high in the sesquiterpene α-copaene, a putative attractant); and to commercial lures containing manuka and phoebe oils, two reported attractive baits. Volatile collections and GC-MS analyses were performed to quantify the sesquiterpene content of test substrates. In the field, traps baited with lychee wood captured more beetles than those with wood from avocado cultivars; traps baited with phoebe oil lures captured more beetles than those with manuka oil lures (the current monitoring tool). In field and laboratory tests, X. glabratus did not show a preference among avocado races in either attraction or host acceptance (initiation of boring). In choice tests, lychee was more attractive than avocado initially, but a higher percentage of beetles bored into avocado, suggesting that lychee emits more powerful olfactory/visual cues, but that avocado contains more of the secondary cues necessary for host recognition. Emissions of α-copaene, β-caryophyllene, and α-humulene were correlated with field captures, and lychee wood may be a source of additional semiochemicals for X. glabratus.

Respiratory mechanics in very low birth weight infants during continuous versus intermittent gavage feeds

This study was designed to determine whether respiratory mechanics in stable, very low birth weight infants changed after replacing intermittent feeds with continuous feeding. We measured static respiratory system compliance, respiratory system resistance, functional residual capacity (FRC), and tidal volume immediately before feeds and at 20, 60, and 120 min after feeds, and again the next day on continuous feeds. Patients selected for enrollment into the study needed to fulfill the following criteria: 1) birth weight and postnatal weight < 1,500 g, 2) no need for mechanical ventilation, positive airway pressure, or supplemental oxygen, 3) receiving and tolerating at least 100 mL/kg/day of intermittent gavage feeds, and 4) no change in methylxanthine or diuretic dosage for 3 days before the study. Respiratory mechanics were measured using the SensorMedics 2600 Pediatric Pulmonary Cart (Yorba Linda, CA). We studied 16 infants (gestational age 28.3 +/- 3.7 weeks, mean +/- SD) at a postnatal age of 10-82 days. The average interindividual coefficient of variance was 20 +/- 2% for static compliance, 35 +/- 6% for resistance, 18 +/- 3% for FRC, and 19 +/- 3% for tidal volume. Repeated-measures analysis of variance did not reveal any significant difference in respiratory mechanics with intermittent vs. continuous feeding. The data suggest that static respiratory mechanics in stable, very low birth weight infants are not affected by changing enteral feeds from intermittent gavage to a continuous schedule.