Toward enhancement of antibody thermostability and affinity by computational design in the absence of antigen

Over the past two decades, therapeutic antibodies have emerged as a rapidly expanding domain within the field of biologics. In silico tools that can streamline the process of antibody discovery and optimization are critical to support a pipeline that is growing more numerous and complex every year. High-quality structural information remains critical for the antibody optimization process, but antibody-antigen complex structures are often unavailable and in silico antibody docking methods are still unreliable. In this study, DeepAb, a deep learning model for predicting antibody Fv structure directly from sequence, was used in conjunction with single-point experimental deep mutational scanning (DMS) enrichment data to design 200 potentially optimized variants of an anti-hen egg lysozyme (HEL) antibody. We sought to determine whether DeepAb-designed variants containing combinations of beneficial mutations from the DMS exhibit enhanced thermostability and whether this optimization affected their developability profile. The 200 variants were produced through a robust high-throughput method and tested for thermal and colloidal stability (Tonset, Tm, Tagg), affinity (KD) relative to the parental antibody, and for developability parameters (nonspecific binding, aggregation propensity, self-association). Of the designed clones, 91% and 94% exhibited increased thermal and colloidal stability and affinity, respectively. Of these, 10% showed a significantly increased affinity for HEL (5- to 21-fold increase) and thermostability (>2.5C increase in Tm1), with most clones retaining the favorable developability profile of the parental antibody. Additional in silico tests suggest that these methods would enrich for binding affinity even without first collecting experimental DMS measurements. These data open the possibility of in silico antibody optimization without the need to predict the antibody-antigen interface, which is notoriously difficult in the absence of crystal structures.

A180 PLACEBO RATES IN MICROSCOPIC COLITIS RANDOMIZED TRIALS: APPLICATIONS FOR FUTURE DRUG DEVELOPMENT USING A HISTORICAL CONTROL ARM

Background

There remains a need to develop effective medical therapies for patients with microscopic colitis (MC) who do not respond, are intolerant, or relapse on budesonide. Conducting randomized trials in MC is logistically and ethically challenging: budesonide is highly effective, and therefore, some institutional review boards have not allowed trials that randomize MC patients to placebo. However, comparing an investigational drug to budesonide is statistically infeasible: powering a non-inferiority study against a budesonide comparator arm with 90% power for a 10% non-inferiority margin would require over 700 subjects, yet fewer than 400 patients have been randomized in all historical MC trials. Therefore, alternative trial designs should be explored in MC, including the use of a historical control arm.

Purpose

To conduct a systematic review and meta-analysis to determine the proportion of placebo responders in MC trials that will inform future trials using a historical placebo comparator, and evaluate factors associated with placebo response.

Method

EMBASE, MEDLINE, and CENTRAL were searched from inception to January 7, 2022, and supplemented with conference abstracts to identify randomized controlled trials (RCTs) using a placebo comparator in adult patients with confirmed MC (either lymphocytic, collagenous, or mixed populations but excluding incomplete MC). The proportion of clinical and histologic responders in the placebo arms were pooled using random-effect models, statistical heterogeneity was evaluated using the I2 method, and the Freeman-Tukey double arcsine transformation was used to compute 95% confidence intervals (CI) using the score statistic and exact binomial method. All analyses were conducted in Stata 17.0.

Result(s)

Twelve placebo controlled RCTs were included, evaluating a total of 391 patients (163 randomized to placebo). The pooled placebo clinical response rate was 24.4% [95% CI 12.4%, 38.4%] (Figure 1), with substantial heterogeneity (I2=60.8%, p<0.01). The pooled histologic response rate was 19.9% [95% CI: 5.3%, 39.0%], with substantial heterogeneity (I2=66.4%, p<0.01). Subgroup analysis demonstrated higher placebo responses in lymphocytic colitis (39.9% [95% CI: 23.9%, 56.7%]) compared to collagenous colitis (19.8% [95% CI: 5.9%, 37.8%]), but not by allowance of baseline anti-diarrheals. Leave-one-out meta-analysis showed a reduction in heterogeneity after removal of Miehlke et al. 2014 (placebo response 21.0% [95% CI: 11.5%, 32.1%], I2=28.6%, p=0.17).

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Conclusion(s)

Approximately 1 in 4 patients in MC trials will respond clinically to placebo and 1 in 5 will demonstrate a histologic response, although with substantial heterogeneity. T his highlights the need for standardized outcome definitions in MC trials and can serve to inform a Bayesian prior estimate for future trials that may consider using a historical placebo comparator.

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None

Disclosure of Interest

P. Hamilton: None Declared, K. Buhler: None Declared, G. Kaplan Grant / Research support from: Ferring, Janssen, AbbVie, GlaxoSmith Kline, Merck, and Shire, Consultant of: AbbVie, Janssen, Pfizer, Amgen, Takeda, and Gilead, C. Lu Consultant of: Abbvie, Janssen, Ferring, and Takeda, Speakers bureau of: Janssen and Abbvie, C. Seow Consultant of: Advisory Boards: Janssen, Abbvie, Takeda, Ferring, Shire, Pfizer, Sandoz, Pharmascience, Fresenius Kabi, Amgen, Speakers bureau of: Janssen, Abbvie, Takeda, Ferring, Shire, Pfizer, Pharmascience, K. Novak Grant / Research support from: AbbVie and Janssen, Consultant of: Advisory board fees from AbbVie, Janssen, Pfizer, Ferring, and Takeda, speaker’s fees from AbbVie, Janssen, and Pfizer, R. Panaccione Consultant of: Abbott, AbbVie, Alimentiv (formerly Robarts), Amgen, Arena Pharmaceuticals, AstraZeneca, Biogen, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Celltrion, Cosmos Pharmaceuticals, Eisai, Elan, Eli Lilly, Ferring, Galapagos, Fresenius Kabi, Genentech, Gilead Sciences, Glaxo-Smith Kline, JAMP Bio, Janssen, Merck, Mylan, Novartis, Oppilan Pharma, Organon, Pandion Pharma, Pendopharm, Pfizer, Progenity, Protagonist Therapeutics, Roche, Sandoz, Satisfai Health, Shire, Sublimity Therapeutics, Takeda Pharmaceuticals, Theravance Biopharma, Trellus, Viatris, UCB. Advisory Boards for: AbbVie, Alimentiv (formerly Robarts), Amgen, Arena Pharmaceuticals, AstraZeneca, Biogen, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Eli Lilly, Ferring, Fresenius Kabi, Genentech, Gilead Sciences, Glaxo-Smith Kline, JAMP Bio, Janssen, Merck, Mylan, Novartis, Oppilan Pharma, Organon, Pandion Pharma, Pfizer, Progenity, Protagonist Therapeutics, Roche, SandozShire, Sublimity Therapeutics, Takeda Pharmaceuticals, Speakers bureau of: AbbVie, Amgen, Arena Pharmaceuticals, Bristol-Myers Squibb, Celgene, Eli Lilly, Ferring, Fresenius Kabi, Gilead Sciences, Janssen, Merck, Organon, Pfizer, Roche, Sandoz, Shire, Takeda Pharmaceuticals, C. Ma Grant / Research support from: Ferring, Pfizer, Consultant of: AbbVie, Alimentiv, American College of Gastroenterology, Amgen, AVIR Pharma Inc, BioJAMP, Bristol Myers Squibb, Celltrion, Ferring, Fresenius Kabi, Janssen, McKesson, Mylan, Sanofi/Regeneron, Takeda, Pendopharm, Pfizer, Roche, Speakers bureau of: : AbbVie, Amgen, AVIR Pharma Inc, Alimentiv, Bristol Myers Squibb, Ferring, Fresenius Kabi, Janssen, Takeda, Pendopharm, and Pfizer

A192 EFFICACY OF USTEKINUMAB IN SMALL BOWEL STRICTURES OF FIBROSTENOTIC CROHN'S DISEASE AS ASSESSED BY INTESTINAL ULTRASOUND

Background

Small bowel Crohn’s disease (CD) strictures can lead to debilitating obstructive symptoms and the deterioration of quality of life. Imaging modalities such as intestinal ultrasound (IUS) are invaluable in the diagnosis of strictures. The use of IUS in CD is rapidly growing, is cost-effective, easily repeatable, and similar in accuracy to magnetic resonance enterography. Evidence for medical management of fibrostenotic CD has been limited to anti-tumor necrosis factor biologics. Studies on the efficacy of other biologic therapies for strictures such as ustekinumab, a p40/interleukin 12 and 23 inhibitor, are lacking.

Purpose

The objective of this study was to evaluate the efficacy of ustekinumab in the treatment of small bowel strictures on IUS.

Method

This retrospective cohort study evaluated the IUS changes of terminal ileal (TI) CD strictures at baseline and 12 months following ustekinumab initiation from 2016 to 2020 at a single tertiary care center. Strictures identified were defined as 1) increased bowel wall thickness (BWT) > 3mm, 2) narrowed luminal apposition, and 3) presence of pre-stenotic dilation (PSD) or the inability to pass the colonoscope through the narrowed area. Changes in sonographic parameters (BWT, luminal size, PSD, length, hyperemia, inflammatory fat, dysfunctional peristalsis) were recorded at baseline prior to initiation of ustekinumab and compared 12 months after treatment. Differences from baseline to 12 months were paired within-person and statistical analysis was performed using paired T-tests for continuous variables and McNemar’s test for categorical variables.

Result(s)

Of the 18 patients identified, 55% (n = 10) were male, median age was 49 years (Q1-Q3: 33-63 years) at initial scan, with median CD duration of 10 years (Q1-Q3: 8-20 years). The majority of TI strictures were surgically naïve (67%, n = 12). Between pre- and 12-month post ustekinumab therapy scans, there was significant improvement in BWT [8.2 mm vs 7.2 mm, p = 0.048], however there was no significant difference in the presence of peri-enteric inflammatory fat (p = 0.10), mean stricture length (17.7 vs 21.7 cm, p = 0.18), and mean stricture lumen diameter (3.3 mm vs 2.7 mm, p = 0.44) (Table 1). There was also no significant difference in the presence of stricture-associated peri-enteric fat (89% vs 67%, p = 0.10), stricture-associated hyperemia (83% vs 89%, p = 0.65) or dysfunctional peristalsis (50% vs 61%, p = 0.41) (Table 1).

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Conclusion(s)

Our study is the first to report the efficacy of ustekinumab in small bowel CD strictures using IUS at baseline and 12 months. This study shows that although ustekinumab leads to improvement in overall sonographic appearance of bowel thickness, it does not improve luminal narrowing nor PSD, two hallmark criteria of fibrostenosis. More extensive studies with larger sample sizes evaluating ustekinumab, or combination therapies, are required to identify their role in stricturing CD.

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None

Disclosure of Interest

None Declared

A35 FORECASTING THE INCIDENCE AND PREVALENCE OF INFLAMMATORY BOWEL DISEASE: A CANADIAN NATION-WIDE ANALYSIS

Background

Canada is currently in the third epidemiological stage in the evolution of IBD: compounding prevalence. A high incidence of IBD, in conjunction with low mortality, leads to a steadily rising prevalence over time. By understanding historical epidemiological trends, we can forecast incidence and prevalence into the future to inform healthcare systems in Canada of the rising burden of IBD to society.

Purpose

To analyze past epidemiological trends in order to forecast the overall incidence and prevalence of IBD, Crohn’s disease (CD), and ulcerative colitis (UC) and stratified by age (<18, 18-64, 65+).

Method

Canadian population-based administrative data was acquired from: AB, BC, SK, MB, QC, and ON. Data were age and sex standardized to the matching year and provincial data aggregated into a representative sample of the Canadian population for prevalence (2002-2014) and incidence (2007-2014: 5-year washout period). Incidence and prevalence (per 100,000 persons) were calculated, with 95% confidence intervals (CI), using Canadian population estimates from Statistics Canada for IBD, CD, UC (IBD-unclassifiable+UC). Autoregressive Integrated Moving Average models were created, and rates forecasted from 2014 to 2035 with 95% prediction intervals (PI). Poisson (or negative binomial) for incidence and log binomial regression for prevalence estimated the Average Annual Percentage Change (AAPC), with 95% CIs, of the forecasted data.

Result(s)

The 2014 incidence of IBD in Canada was 28.4 per 100,000 (95%CI: 27.8, 29.0) and forecasted to significantly increase (AAPC: 0.58%; 95%CI: 0.04, 1.04) from 30.0 per 100,000 in 2023 to 32.1 (95%PI: 27.9, 36.3) in 2035. Pediatric onset IBD was 13.9 per 100,000 (95%CI: 13.0, 14.9) in 2014 and is forecasted to significantly increase to 18.0 per 100,000 (95%PI: 15.7, 20.2) in 2035 with an AAPC of 1.23% (95%CI: 0.76, 1.63). Adult and elderly onset incidence rates were forecasted to remain stable. Prevalence of IBD increased between 2002 (389 per 100,000) and 2014 (636 per 100,000) and is forecasted to continue to climb by an AAPC of 2.44% (95%CI: 2.34, 2.53). In 2023, the prevalence of IBD is 825 per 100,000. By 2035 prevalence is forecasted to climb to 1075 per 100,000 (95%PI: 1047, 1103) with 470,000 Canadians living with IBD. Prevalence across all age strata were forecasted to significantly increase. The highest AAPC was seen in the elderly (2.76%; 95%CI: 2.73, 2.79) with a prevalence of 841 per 100,000 (95%CI: 834, 849) in 2014 and forecasted to climb to 1534 per 100,000 (95%PI: 1519, 1550) in 2035.

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Conclusion(s)

Incidence of IBD continues to rise in Canada, driven by pediatric-onset IBD. In 2023, over 320,000 Canadians (0.83%) will be living with IBD. By 2035 prevalence will exceed 1% of the population with approximately 470,000 individuals in Canada with IBD. Future research should establish the environmental determinates of IBD that may influence temporal trends in the incidence of IBD, while healthcare systems adapt to the compounding prevalence of IBD.

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CIHR, Other

Please indicate your source of funding;

The Leona M. and Harry B. Helmsley Charitable Trust

Disclosure of Interest

S. Coward: None Declared, E. Benchimol Consultant of: Hoffman La-Roche Limited and Peabody & Arnold LLP for matters unrelated to medications used to treat inflammatory bowel disease and McKesson Canada and the Dairy Farmers of Ontario for matters unrelated to medications used to treat inflammatory bowel disease., C. Bernstein Grant / Research support from: Unrestricted educational grants from Abbvie Canada, Janssen Canada, Pfizer Canada, Bristol Myers Squibb Canada, and Takeda Canada. Has received research grants from Abbvie Canada, Amgen Canada, Pfizer Canada, and Sandoz Canada and contract grants from Janssen, Abbvie and Pfizer, Consultant of: Abbvie Canada, Amgen Canada, Bristol Myers Squibb Canada, JAMP Pharmaceuticals, Janssen Canada, Pfizer Canada, Sandoz Canada, and Takeda., Speakers bureau of: Abbvie Canada, Janssen Canada, Pfizer Canada and Takeda Canada, J. A. Avina-Zubieta: None Declared, A. Bitton: None Declared, L. Hracs: None Declared, J. Jones Consultant of: Janssen, Abbvie, Pfizer, Takeda, Speakers bureau of: Janssen, Abbvie, Pfizer, Takeda, E. Kuenzig: None Declared, L. Lu: None Declared, S. Murthy: None Declared, Z. Nugent: None Declared, A. Otley Grant / Research support from: Unrestricted educational grants from AbbVie Canada and Janssen Canada, Consultant of: Advisory boards of AbbVie Canada, Janssen Canada and Nestle, R. Panaccione Consultant of: Abbott, AbbVie, Alimentiv (formerly Robarts), Amgen, Arena Pharmaceuticals, AstraZeneca, Biogen, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Celltrion, Cosmos Pharmaceuticals, Eisai, Elan, Eli Lilly, Ferring, Galapagos, Fresenius Kabi, Genentech, Gilead Sciences, Glaxo-Smith Kline, JAMP Bio, Janssen, Merck, Mylan, Novartis, Oppilan Pharma, Organon, Pandion Pharma, Pendopharm, Pfizer, Progenity, Protagonist Therapeutics, Roche, Sandoz, Satisfai Health, Shire, Sublimity Therapeutics, Takeda Pharmaceuticals, Theravance Biopharma, Trellus, Viatris, UCB. Advisory Boards for: AbbVie, Alimentiv (formerly Robarts), Amgen, Arena Pharmaceuticals, AstraZeneca, Biogen, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Eli Lilly, Ferring, Fresenius Kabi, Genentech, Gilead Sciences, Glaxo-Smith Kline, JAMP Bio, Janssen, Merck, Mylan, Novartis, Oppilan Pharma, Organon, Pandion Pharma, Pfizer, Progenity, Protagonist Therapeutics, Roche, Sandoz Shire, Sublimity Therapeutics, Takeda Pharmaceuticals, Speakers bureau of: AbbVie, Amgen, Arena Pharmaceuticals, Bristol-Myers Squibb, Celgene, Eli Lilly, Ferring, Fresenius Kabi, Gilead Sciences, Janssen, Merck, Organon, Pfizer, Roche, Sandoz, Shire, Takeda Pharmaceuticals, J.-N. Pena-Sanchez: None Declared, H. Singh Consultant of: Pendopharm, Amgen Canada, Bristol Myers Squibb Canada, Roche Canada, Sandoz Canada, Takeda Canada, and Guardant Health, Inc., L. Targownik Grant / Research support from: Investigator initiated funding from Janssen Canada, Consultant of: [Advisory board] AbbVie Canada, Takeda Canada, Merck Canada, Pfizer Canada, Janssen Canada, Roche Canada, and Sandoz Canada, J. Windsor: None Declared, G. Kaplan Grant / Research support from: Ferring, Janssen, AbbVie, GlaxoSmith Kline, Merck, and Shire, Consultant of: Gilead, Speakers bureau of: AbbVie, Janssen, Pfizer, Amgen, and Takeda

A177 RISK OF VENOUS THROMBOEMBOLISM IN COVID-19 PATIENTS WITH INFLAMMATORY BOWEL DISEASE: A POPULATION-BASED MATCHED COHORT STUDY

Background

Venous thromboembolism (VTE), is associated with significant morbidity and mortality. Inflammation increases the risk of VTE, and it is a well-recognised complication of both inflammatory bowel disease (IBD) and COVID-19.

Purpose

To compare the risk of VTE among individuals with and without IBD following a positive COVID-19 test.

Method

Using health administrative data from Ontario, Canada we conducted a retrospective matched cohort study.All Ontario residents with a positive SARS-CoV-2 PCR test between January 1,2020 and December 30,2021 who had been diagnosed with IBD prior to their COVID-19 infection (identified using a validated algorithm) were matched to 5 individuals without IBD based on year of birth, sex, mean neighbourhood income quintile, date of positive COVID-19 test, and rural/urban residence. Individuals with a cancer diagnosis in the 5 years prior to their first COVID-19 positive test were excluded. Individuals were followed from positive COVID-19 PCR test until VTE event, death, migration out of Ontario or March 31, 2022.VTEs were identified from emergency department or hospitalization data using ICD-10 codes. Incidence rate of VTEs among individuals with IBD were assessed at 1, 6 and 12 months. Proportional cause-specific hazards models compared the risk of VTEs in people with and without IBD, treating death as a competing risk and controlling for vaccination status (2^nd dose ≥14 days prior to positive COVID-19 test) and a history of VTE (VTE in the 5 years prior to infection).

Result(s)

There were 4293 people with IBD (44% Crohn’s disease, mean age ±SD 46.1±17.2 y) matched to 20,207 with out IBD (mean age 45.3±16.8 y) with a positive SARS-CoV-2 PCR test. Within 1 month of a positive COVID-19 test, the crude incidence rate of VTE in individuals with IBD was 4.77(95%CI, 4.75-4.80) per 100,000 person-days compared to 8.25(95%CI, 8.20-8.30) per 100,000 among people without IBD.Within 6 months, these rates were 1.86(95%CI, 1.86-1.87) and 2.12(95%CI, 2.11-2.12) per 100,000 person-days among people with and without IBD, respectivley. Within 12 months, these rates were 1.59(95% CI, 1.58-1.59) and 1.42(95% CI, 1.42-1.42) per 100,000 person-days among people with and without IBD, respectively.After adjusting for vaccination status and history of VTE there was no difference in the risk of VTE for people with and without IBD (HR 1.08, 95%CI, 0.64 to 1.83).

Conclusion(s)

IBD patients with COVID-19 were not more likely to experience a VTE infection compared with the general popluation. The risk of VTE was highest soon after COVID-19 and declined thereafter.

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None

Disclosure of Interest

None Declared

A210 THE BURDEN OF IBD HOSPITALIZATION IN CANADA: AN ASSESSMENT OF THE CURRENT AND FUTURE BURDEN IN A NATION-WIDE ANALYSIS

Background

Hospitalizations pose a significant burden on both the individual and the healthcare system. Those with inflammatory bowel disease (IBD) are at increased risk of hospitalization as compared to the general population due to flaring of disease activity and complications related to IBD. The advent of biologics over the past twenty years may have influenced the rates of hospitalization for IBD.

Purpose

To assess current and forecast the overall hospitalization rates of those with IBD stratified by types of hospitalizations (all cause hospitalizations, IBD-related, and IBD-specific).

Method

Population-based administrative data on hospitalization of IBD (2002-2014) were obtained from: AB, BC, MB, and SK. Data were age and sex standardized to the matching year and aggregated into a representative sample of the Canadian population. Hospitalization rates were assessed as follows: 1. All cause hospitalizations: all admissions regardless of indication; 2. IBD-specific: an admission directly resulting from IBD (e.g., IBD-flare); 3. IBD-related: an admission for IBD, or a symptom or comorbidity associated with IBD (e.g. rheumatoid arthritis). Using prevalence estimates from the provinces, hospitalization rates (per 100 persons with IBD) were calculated, with 95% confidence intervals (CI). Autoregressive Integrated Moving Average models were created to estimate number of hospitalizations and corresponding prevalence to forecast hospitalization rates to 2030 with 95% prediction intervals (PI). Poisson (or negative binomial) regression estimated the Average Annual Percentage Change (AAPC), with 95% CIs, of the forecasted data.

Result(s)

In 2002 there were 35.3 per 100 (95%CI: 34.7, 35.9) all cause hospitalizations for IBD patients and this decreased to 24.9 per 100 (24.5, 25.2) in 2014. Similar trends were seen for IBD-specific hospitalizations [16.8 per 100 (95%CI: 16.4, 17.2) in 2002 to 8.7 per 100 (95%CI: 8.5, 9.0) in 2014] and IBD-related (22.6 per 100 (95%CI: 22.1, 23.1) in 2002 to 13.4 per 100 (95%CI: 13.2, 13.7) in 2014). When forecasted out to 2030 all hospitalization types were significantly decreasing—the AAPC for all cause hospitalizations was -2.12% (95%CI: -2.31, -1.93), -3.77% (95%CI: -4.63, -3.08) for IBD-specific, and -3.09% (95%CI: -3.65, -2.62) for IBD-related. By 2030, the rates of hospitalization are forecasted to be 17.0 per 100 (95%PI: 16.2, 17.9), 4.6 per 100 (95%PI: 3.7, 5.4), and 7.9 per 100 (95%PI: 6.9, 8.9) for all cause, IBD-specific, and IBD-related, respectively.

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Conclusion(s)

In Canada, rates of hospitalizations for those with IBD have decreased from 2002 to 2014. The use of anti-TNF therapy in conjunction with the evolution of clinical monitoring, management and guidelines, likely has contributed to dropping hospitalization rates. Forecast models estimate a continued drop in hospitalization rates out to 2030. Importantly, healthcare resource planning should account for the shift from hospital-based to clinic-centric models of IBD care.

Please acknowledge all funding agencies by checking the applicable boxes below

CIHR

Disclosure of Interest

S. Coward: None Declared, E. Benchimol Consultant of: Hoffman La-Roche Limited and Peabody & Arnold LLP for matters unrelated to medications used to treat inflammatory bowel disease and McKesson Canada and the Dairy Farmers of Ontario for matters unrelated to medications used to treat inflammatory bowel disease., C. Bernstein Grant / Research support from: Unrestricted educational grants from Abbvie Canada, Janssen Canada, Pfizer Canada, Bristol Myers Squibb Canada, and Takeda Canada. Has received research grants from Abbvie Canada, Amgen Canada, Pfizer Canada, and Sandoz Canada and contract grants from Janssen, Abbvie and Pfizer, Consultant of: Abbvie Canada, Amgen Canada, Bristol Myers Squibb Canada, JAMP Pharmaceuticals, Janssen Canada, Pfizer Canada, Sandoz Canada, and Takeda., Speakers bureau of: Abbvie Canada, Janssen Canada, Pfizer Canada and Takeda Canada, J. A. Avina-Zubieta: None Declared, A. Bitton: None Declared, L. Hracs: None Declared, J. Jones Consultant of: Janssen, Abbvie, Pfizer, Takeda, Speakers bureau of: Janssen, Abbvie, Pfizer, Takeda, E. Kuenzig: None Declared, L. Lu: None Declared, S. Murthy: None Declared, Z. Nugent: None Declared, A. Otley Grant / Research support from: Unrestricted educational grants from AbbVie Canada and Janssen Canada, Consultant of: Advisory boards of AbbVie Canada, Janssen Canada and Nestle, R. Panaccione Consultant of: Abbott, AbbVie, Alimentiv (formerly Robarts), Amgen, Arena Pharmaceuticals, AstraZeneca, Biogen, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Celltrion, Cosmos Pharmaceuticals, Eisai, Elan, Eli Lilly, Ferring, Galapagos, Fresenius Kabi, Genentech, Gilead Sciences, Glaxo-Smith Kline, JAMP Bio, Janssen, Merck, Mylan, Novartis, Oppilan Pharma, Organon, Pandion Pharma, Pendopharm, Pfizer, Progenity, Protagonist Therapeutics, Roche, Sandoz, Satisfai Health, Shire, Sublimity Therapeutics, Takeda Pharmaceuticals, Theravance Biopharma, Trellus, Viatris, UCB. Advisory Boards for: AbbVie, Alimentiv (formerly Robarts), Amgen, Arena Pharmaceuticals, AstraZeneca, Biogen, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Eli Lilly, Ferring, Fresenius Kabi, Genentech, Gilead Sciences, Glaxo-Smith Kline, JAMP Bio, Janssen, Merck, Mylan, Novartis, Oppilan Pharma, Organon, Pandion Pharma, Pfizer, Progenity, Protagonist Therapeutics, Roche, Sandoz Shire, Sublimity Therapeutics, Takeda Pharmaceuticals, Speakers bureau of: AbbVie, Amgen, Arena Pharmaceuticals, Bristol-Myers Squibb, Celgene, Eli Lilly, Ferring, Fresenius Kabi, Gilead Sciences, Janssen, Merck, Organon, Pfizer, Roche, Sandoz, Shire, Takeda Pharmaceuticals, J.-N. Pena-Sanchez: None Declared, H. Singh Consultant of: Pendopharm, Amgen Canada, Bristol Myers Squibb Canada, Roche Canada, Sandoz Canada, Takeda Canada, and Guardant Health, Inc.,, L. Targownik Grant / Research support from: Investigator initiated funding from Janssen Canada, Consultant of: [Advisory board] AbbVie Canada, Takeda Canada, Merck Canada, Pfizer Canada, Janssen Canada, Roche Canada, and Sandoz Canada, J. Windsor: None Declared, G. Kaplan Grant / Research support from: Ferring, Janssen, AbbVie, GlaxoSmith Kline, Merck, and Shire, Consultant of: Gilead, Speakers bureau of: AbbVie, Janssen, Pfizer, Amgen, and Takeda

A154 CANCERS ASSOCIATED WITH INFLAMMATORY BOWEL DISEASE IN CANADA: A POPULATION-BASED ANALYSIS OF CASES AND MATCHED CONTROLS

Background

Individuals with inflammatory bowel disease (IBD) are known to have a higher risk of digestive tract cancers and cancers associated with immunosuppression. As the IBD population is ageing, age-related cancers may be more commonly diagnosed.

Purpose

To assess whether IBD patients were at a higher odds of incident cancers than their matched controls stratified by age above and below 65 years.

Method

A population-based surveillance study was conducted in Alberta, Canada (April 1, 2002 to March 30, 2018). A validated algorithm identified cases of IBD. Each case was age and sex matched to up to 10 non-IBD cases from the general population and linked to the Alberta provincial cancer registry to extract pathology-confirmed incident cancer. Controls were removed if they were not residents of Alberta at the time the matched case was diagnosed with IBD. Only incident cancers diagnosed after the diagnosis of IBD (or matched indexed date for controls) were considered. Age was calculated based on year of inclusion in the cohort or, if applicable, the year of cancer diagnosis. Cancer diagnoses were classified: bladder, biliary and liver, breast, cervix, colorectal, endometrium, gastrointestinal, gynecological, head and neck, hematological, kidney, lung, melanoma, neurological, non-melanoma, pancreas, prostate, renal and bladder, small intestine, thyroid, and miscellaneous. Odds ratios (OR), with 95% confidence intervals (CI), compared IBD cases to matched controls using conditional logistic regression. Stratified analysis at age 65 (<65 and ≥65) was done for all cancers.

Result(s)

Overall, 3695 incident cancers were diagnosed among 35,763 individuals with IBD as compared to 22,687 cancers among 289,212 controls (OR:1.12; 95%CI: 1.08, 1.16). Those less than 65 years old were at higher odds of developing cancer (1.20; 95%CI: 1.15, 1.26) than those ≥65 (0.97; 95%CI: 0.90, 1.04). Those with IBD had a higher odds biliary and liver (7.41; 95%CI: 5.58, 9.84) and gastrointestinal (2.26; 95%CI: 2.06, 2.48), which including: colorectal (1.78; 95%CI: 1.57, 2.02), pancreas (7.79; 95%CI: 5.53, 10.97), and small intestine (6.59; 95%CI: 4.65, 9.35). Melanoma and non-melanoma, head and neck, and thyroid cancers did not have an increased odds but hematological, lung, neurological, and kidney cancers did show an increased odds among those with IBD. Cancers outside of the gastrointestinal tract were at a lower odds for IBD patients, including: bladder (0.68; 95%CI: 0.54, 0.87), breast (0.72; 95%CI: 0.64, 0.81), gynecological (incl. cervix (0.68; 95%CI: 0.61, 0.78) and endometrium (0.48; 95%CI: 0.34, 0.66), and prostate (0.64; 95%CI: 0.57, 0.73).

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Conclusion(s)

Under the age of 65, individuals with IBD have a higher odds of being diagnosed with cancer than the general population, with cancers of the digestive tract driving this association across the age spectrum. Healthcare providers should be aware of higher occurrence of hematological, neurological, lung and renal cancers in those with IBD.

Please acknowledge all funding agencies by checking the applicable boxes below

CIHR

Disclosure of Interest

S. Coward: None Declared, S. Murthy: None Declared, H. Singh Consultant of: Pendopharm, Amgen Canada, Bristol Myers Squibb Canada, Roche Canada, Sandoz Canada, Takeda Canada, and Guardant Health, Inc., E. Benchimol Consultant of: Hoffman La-Roche Limited and Peabody & Arnold LLP for matters unrelated to medications used to treat inflammatory bowel disease and McKesson Canada and the Dairy Farmers of Ontario for matters unrelated to medications used to treat inflammatory bowel disease., E. Kuenzig: None Declared, G. Kaplan Grant / Research support from: Ferring, Janssen, AbbVie, GlaxoSmith Kline, Merck, and Shire, Consultant of: Gilead, Speakers bureau of: AbbVie, Janssen, Pfizer, Amgen, and Takeda

A195 DURABILITY OF SEROLOGICAL RESPONSES AFTER SECOND, THIRD AND FOURTH DOSE OF SARS-COV-2 VACCINATION IN INFLAMMATORY BOWEL DISEASE: A PROSPECTIVE COHORT STUDY

Background

Adequate serological responses following two-dose regimens and additional doses of SARS-CoV-2 vaccination have been demonstrated for the vast majority of those with IBD. However, antibody levels following 2^nd, 3^rd, and 4^th dose SARS-CoV-2 vaccination may decrease over time in the IBD population.

Purpose

We assessed the durability of serological responses to 2^nd, 3^rd, and 4^th dose SARS-CoV-2 vaccination over time in a cohort of IBD patients.

Method

Adults with IBD who received at least one dose of a SARS-CoV-2 vaccine (n=559) were evaluated for serological response to the spike protein of SARS-CoV-2 using the Abbott IgG II Quant assay with a seroconversion threshold of ≥ 50 AU/mL. The geometric mean titer (GMT) with 95% confidence intervals (CI) were calculated and stratified by weeks (1–8, 8–16, 16–24, 24+ weeks) after each vaccine dose. We compared stratified GMTs with Mann–Whitney U tests using a significance level of 0.05.

Result(s)

Our cohort (n=559) comprised the following patient characteristics: 82.8% were 18–65 years-old (n = 463), 53.1% were female (n =297), and 71.6% had Crohn’s disease (n =400). IBD medications were classified in the following mutually exclusive groups: No immunosuppressives 10.5% (n = 59), anti-TNF monotherapy 35.8% (n = 200), immunomodulatory monotherapy 2.1% (n =12 ), vedolizumab 11.8% (n =66 ), ustekinumab 20.4% (n =114 ), tofacitinib 1.2% (n =7 ), combination therapy 15.9% (n = 89), and prednisone 2.1% (n =12). For vaccine type, 85.6% and 82.3% had Pfizer for 3^rd and 4^th dose, respectively, while the remainder had Moderna. Seroconversion rates 1–8 weeks after 3^rd and 4^th dose were both 99.9%.

Figure 1 compares GMTs with 95% CI by weeks after each vaccine dose. GMTs are highest 1–8 weeks after 2^nd dose (4053 AU/mL; 95% CI: 3468, 4737 AU/mL; n=337), 3^rd dose (12116 AU/mL; 10413, 14098 AU/mL; n=256), and 4^th dose (14337 AU/mL; 10429, 19710 AU/mL; n=67). Subsequently, antibody levels decay from 1–8 weeks to 8–16 weeks (p<0.001) for 2^nd dose (mean difference: –2224 AU/mL), 3^rd dose (mean difference: –7526 AU/mL), and 4^th dose (mean difference: –9715 AU/mL). Compared to 16–24 weeks after 2^nd dose, antibody levels 24+ weeks after were similar (GMTs: 795 AU/mL vs. 1043 AU/mL, p=0.52). For third dose, antibody levels 8–16 weeks and 16–24 weeks after vaccination were similar (4590 AU/mL vs. 4073 AU/mL, p=0.73) along with 16–24 weeks compared to 24+ weeks after vaccination (4073 AU/mL vs. 5876 AU/mL, p=0.18).

Image

Conclusion(s)

Within 1–8 weeks after each dose of vaccine, serological responses spikes with each subsequent dose yielding a higher GMT. While antibody levels decay 8–16 weeks after each dose, similar GMT levels beyond 16 weeks may indicate durability of antibody levels over a longer duration of time.

Disclosure of Interest

None Declared

A169 THE DIRECT COSTS OF INFLAMMATORY BOWEL DISEASE IN CANADA: A POPULATION-BASED ANALYSIS OF HISTORICAL AND CURRENT COSTS

Background

Inflammatory bowel disease (IBD) is a costly disease to manage due to hospitalizations, regular ambulatory monitoring, and expensive pharmaceutical therapies. While hospitalization rates have fallen, the increased use of biologics have escalated the cost of care to the healthcare system.

Purpose

To assess historical direct healthcare costs of the IBD population in Canada.

Method

Population-based administrative costing data were obtained from: Alberta, British Columbia, and Manitoba. Costs were calculated based on administrative data (2009 to 2016) which captured: hospitalizations, physician costs, ambulatory care such as: emergency visits, day surgery, and colonoscopy (AB only), and medication costs of IBD-specific medications, such as: mesalamine, biologics, steroids, and immunomodulators. Costs were converted to 2020 dollars using the consumer price index. Average annual cost per person (ACPP) was calculated for each province. Using province specific IBD prevalence estimates these ACPP were meta-analyzed to obtain the annual weighted costs, with 95% confidence intervals (CI), and these costs underwent meta-regression to ascertain the average annual change in cost per year. An Autoregressive Integrated Moving Average model was created to estimate the ACPP in 2023 with 95% prediction intervals (PI). Canada-wide total direct care costs of IBD patients, in billions (B), were calculated using the ACPP, Canada-specific IBD prevalence estimates (historical and forecasted), and total Canadian population calculations from Statistics Canada (historical and forecasted).

Result(s)

In 2009 the ACPP was $7000 (95%CI: 5389, 8610), representing $1.18B (95%CI: 0.91B, 1.45B) in direct healthcare costs in Canada for all IBD patients. The ACPP in 2016 was increased to $10,336 (95%CI: 6803, 13869), which equates to $2.37B (95%CI: 1.56B, 3.18B) per year in direct healthcare costs. From 2009 to 2016, the ACPP increased an average of $450 (95%CI: 132, 767) per year. If these historical trends continue to 2023 the ACPP is forecasted to be $13,333 (95%PI: 12827, 13839) per person per year. The largest contributor to these costs is medications—accounting for an estimated 50% of the total costs of IBD patients.

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Conclusion(s)

The direct healthcare cost of IBD has risen steadily from 2009 to 2016 when the healthcare system spent over $10,000 per person with IBD and $2.37B nationwide. The primary driver of costs is medical management. Forecast models estimate that the annual cost may be over $13,000 per person in 2023. However, these estimates do not account for advent and increased uptake of novel biologics and small molecules, nor the downward cost pressure of biosimilars. These costs are those paid directly by the healthcare system and do not account for those born by the individual—it is estimated that the true cost of IBD (direct and indirect) is much higher.

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CIHR

Disclosure of Interest

S. Coward: None Declared, E. Benchimol Consultant of: Hoffman La-Roche Limited and Peabody & Arnold LLP for matters unrelated to medications used to treat inflammatory bowel disease and McKesson Canada and the Dairy Farmers of Ontario for matters unrelated to medications used to treat inflammatory bowel disease., C. Bernstein Grant / Research support from: Unrestricted educational grants from Abbvie Canada, Janssen Canada, Pfizer Canada, Bristol Myers Squibb Canada, and Takeda Canada. Has received research grants from Abbvie Canada, Amgen Canada, Pfizer Canada, and Sandoz Canada and contract grants from Janssen, Abbvie and Pfizer, Consultant of: Abbvie Canada, Amgen Canada, Bristol Myers Squibb Canada, JAMP Pharmaceuticals, Janssen Canada, Pfizer Canada, Sandoz Canada, and Takeda., Speakers bureau of: Abbvie Canada, Janssen Canada, Pfizer Canada and Takeda Canada, J. A. Avina-Zubieta: None Declared, A. Bitton: None Declared, L. Hracs: None Declared, J. Jones Consultant of: Janssen, Abbvie, Pfizer, Takeda, Speakers bureau of: Janssen, Abbvie, Pfizer, Takeda, E. Kuenzig: None Declared, L. Lu: None Declared, S. Murthy: None Declared, Z. Nugent: None Declared, A. Otley Grant / Research support from: Unrestricted educational grants from AbbVie Canada and Janssen Canada, Consultant of: Advisory boards of AbbVie Canada, Janssen Canada and Nestle, R. Panaccione Consultant of: Abbott, AbbVie, Alimentiv (formerly Robarts), Amgen, Arena Pharmaceuticals, AstraZeneca, Biogen, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Celltrion, Cosmos Pharmaceuticals, Eisai, Elan, Eli Lilly, Ferring, Galapagos, Fresenius Kabi, Genentech, Gilead Sciences, Glaxo-Smith Kline, JAMP Bio, Janssen, Merck, Mylan, Novartis, Oppilan Pharma, Organon, Pandion Pharma, Pendopharm, Pfizer, Progenity, Protagonist Therapeutics, Roche, Sandoz, Satisfai Health, Shire, Sublimity Therapeutics, Takeda Pharmaceuticals, Theravance Biopharma, Trellus, Viatris, UCB. Advisory Boards for: AbbVie, Alimentiv (formerly Robarts), Amgen, Arena Pharmaceuticals, AstraZeneca, Biogen, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Eli Lilly, Ferring, Fresenius Kabi, Genentech, Gilead Sciences, Glaxo-Smith Kline, JAMP Bio, Janssen, Merck, Mylan, Novartis, Oppilan Pharma, Organon, Pandion Pharma, Pfizer, Progenity, Protagonist Therapeutics, Roche, Sandoz Shire, Sublimity Therapeutics, Takeda Pharmaceuticals, Speakers bureau of: AbbVie, Amgen, Arena Pharmaceuticals, Bristol-Myers Squibb, Celgene, Eli Lilly, Ferring, Fresenius Kabi, Gilead Sciences, Janssen, Merck, Organon, Pfizer, Roche, Sandoz, Shire, Takeda Pharmaceuticals, J.-N. Pena-Sanchez: None Declared, H. Singh Consultant of: Pendopharm, Amgen Canada, Bristol Myers Squibb Canada, Roche Canada, Sandoz Canada, Takeda Canada, and Guardant Health, Inc.,, L. Targownik Grant / Research support from: Investigator initiated funding from Janssen Canada, Consultant of: [Advisory board] AbbVie Canada, Takeda Canada, Merck Canada, Pfizer Canada, Janssen Canada, Roche Canada, and Sandoz Canada, J. Windsor: None Declared, G. Kaplan Grant / Research support from: Ferring, Janssen, AbbVie, GlaxoSmith Kline, Merck, and Shire, Consultant of: Gilead, Speakers bureau of: AbbVie, Janssen, Pfizer, Amgen, and Takeda

Developability profiling of a panel of Fc engineered SARS-CoV-2 neutralizing antibodies

To combat the COVID-19 pandemic, potential therapies have been developed and moved into clinical trials at an unprecedented pace. Some of the most promising therapies are neutralizing antibodies against SARS-CoV-2. In order to maximize the therapeutic effectiveness of such neutralizing antibodies, Fc engineering to modulate effector functions and to extend half-life is desirable. However, it is critical that Fc engineering does not negatively impact the developability properties of the antibodies, as these properties play a key role in ensuring rapid development, successful manufacturing, and improved overall chances of clinical success. In this study, we describe the biophysical characterization of a panel of Fc engineered ("TM-YTE") SARS-CoV-2 neutralizing antibodies, the same Fc modifications as those found in AstraZeneca's Evusheld (AZD7442; tixagevimab and cilgavimab), in which the TM modification (L234F/L235E/P331S) reduce binding to FcγR and C1q and the YTE modification (M252Y/S254T/T256E) extends serum half-life. We have previously shown that combining both the TM and YTE Fc modifications can reduce the thermal stability of the CH2 domain and possibly lead to developability challenges. Here we show, using a diverse panel of TM-YTE SARS-CoV-2 neutralizing antibodies, that despite lowering the thermal stability of the Fc CH2 domain, the TM-YTE platform does not have any inherent developability liabilities and shows an in vivo pharmacokinetic profile in human FcRn transgenic mice similar to the well-characterized YTE platform. The TM-YTE is therefore a developable, effector function reduced, half-life extended antibody platform.

Qualification of a Biolayer Interferometry Assay to Support AZD7442 Resistance Monitoring

AZD7442, a combination of two long-acting monoclonal antibodies (tixagevimab [AZD8895] and cilgavimab [AZD1061]), has been authorized for the prevention and treatment of coronavirus disease 2019 (COVID-19). The rapid emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants requires methods capable of quickly characterizing resistance to AZD7442. To support AZD7442 resistance monitoring, a biolayer interferometry (BLI) assay was developed to screen the binding of tixagevimab and cilgavimab to SARS-CoV-2 spike proteins to reduce the number of viral variants for neutralization susceptibility verification. Six spike variants were chosen to assess the assay's performance: four with decreased affinity for tixagevimab (F486S:D614G and F486W:D614G proteins) or cilgavimab (S494L:D614G and K444R:D614G proteins) and two reference proteins (wild-type HexaPro and D614G protein). Equilibrium dissociation constant (KD) values from each spike protein were used to determine shifts in binding affinity. The assay's precision, range, linearity, and limits of quantitation were established. Qualification acceptance criteria determined whether the assay was fit for purpose. By bypassing protein purification, the BLI assay provided increased screening throughput. Although limited correlation between pseudotype neutralization and BLI data (50% inhibitory concentration versus KD) was observed for full immunoglobulins (IgGs), the correlations for antibody fragments (Fabs) were stronger and reflected a better comparison of antibody binding kinetics with neutralization potency. Therefore, despite strong assay performance characteristics, the use of full IgGs limited the screening utility of the assay; however, the Fab approach warrants further exploration as a rapid, high-throughput variant-screening method for future resistance-monitoring programs. IMPORTANCE SARS-CoV-2 variants harbor multiple substitutions in their spike trimers, potentially leading to breakthrough infections and clinical resistance to immune therapies. For this reason, a BLI assay was developed and qualified to evaluate the reliability of screening SARS-CoV-2 spike trimer variants against anti-SARS-CoV-2 monoclonal antibodies (MAbs) tixagevimab and cilgavimab, the components of AZD7442, prior to in vitro pseudovirus neutralization susceptibility verification testing. The assay bypasses protein purification with rapid assessment of the binding affinity of each MAb for each recombinant protein, potentially providing an efficient preliminary selection step, thus allowing a reduced testing burden in the more technically complex viral neutralization assays. Despite precise and specific measures, an avidity effect associated with MAb binding to the trimer confounded correlation with neutralization potency, negating the assay's utility as a surrogate for neutralizing antibody potency. Improved correlation with Fabs suggests that assay optimization could overcome any avidity limitation, warranting further exploration to support future resistance-monitoring programs.

Improving the In Vivo Efficacy of an Anti-Tac (CD25) Immunotoxin by Pseudomonas Exotoxin A Domain II Engineering

Tac (CD25) is expressed on multiple hematologic malignancies and is a target for cancer therapies. LMB-2 is an extremely active anti-Tac recombinant immunotoxin composed of an Fv that binds to Tac and a 38-kDa fragment of Pseudomonas exotoxin A (PE38). Although LMB-2 has shown high cytotoxicity toward Tac-expressing cancer cells in clinical trials, its efficacy was hampered by the formation of anti-drug antibodies against the immunogenic bacterial toxin and by dose-limiting off-target toxicity. To reduce toxin immunogenicity and nonspecific toxicity, we introduced six point mutations into domain III that were previously shown to reduce T-cell immunogenicity and deleted domain II from the toxin, leaving only the 11aa furin cleavage site, which is required for cytotoxic activity. Although this strategy has been successfully implemented for mesothelin and CD22-targeting immunotoxins, we found that removal of domain II significantly lowered the cytotoxic activity of anti-Tac immunotoxins. To restore cytotoxic activity in the absence of PE domain II, we implemented a combined rational design and screening approach to isolate highly active domain II-deleted toxin variants. The domain II-deleted variant with the highest activity contained an engineered disulfide-bridged furin cleavage site designed to mimic its native conformation within domain II. We found that this approach restored 5-fold of the cytotoxic activity and dramatically improved the MTD. Both of these improvements led to significantly increased antitumor efficacy in vivo We conclude that the next-generation anti-Tac immunotoxin is an improved candidate for targeting Tac-expressing malignancies. Mol Cancer Ther; 17(7); 1486-93. ©2018 AACR.

Unique binding modes for the broad neutralizing activity of single-chain variable fragments (scFv) targeting CD4-induced epitopes

Background

The CD4-induced (CD4i) epitopes in gp120 includes the co-receptor binding site, which are formed and exposed after interaction with CD4. Monoclonal antibodies (mAbs) to the CD4i epitopes exhibit limited neutralizing activity because of restricted access to their epitopes. However, small fragment counterparts such as single-chain variable fragments (scFvs) have been reported to neutralize a broad range of viruses compared with the full-size IgG molecule. To identify the CD4i epitope site responsible for this broad neutralization we constructed three scFvs of anti-CD4i mAbs from a human immunodeficiency virus type 1 (HIV-1)-infected elite controller, and investigated the neutralization coverage and precise binding site in the CD4i epitopes.

Results

We constructed scFvs from the anti-CD4i mAbs, 916B2, 4E9C, and 25C4b and tested their neutralization activity against a panel of 66 viruses of multi-subtype. Coverage of neutralization by the scFvs against this panel of pseudoviruses was 89% (59/66) for 4E9C, 95% (63/66) for 25C4b and 100% (66/66) for 916B2. Analysis using a series of envelope glycoprotein mutants revealed that individual anti-CD4i mAbs showed various dependencies on the hairpin 1 (H1) and V3 base. The binding profiles of 25C4b were similar to those of 17b, and 25C4b bound the region spanning multiple domains of H1 and hairpin 2 (H2) of the bridging sheet and V3 base. For 4E9C, the V3-base dependent binding was apparent from no binding to mutants containing the ΔV3 truncation. In contrast, binding of 916B2 was dependent on the H1 region, which is composed of β2 and β3 strands, because mutants containing the H1 truncation did not show any reactivity to 916B2. Although the H1 region structure is affected by CD4 engagement, the results indicate the unique nature of the 916B2 epitope, which may be structurally conserved before and after conformational changes of gp120.

Conclusions

Identification of a unique structure of the H1 region that can be targeted by 916B2 may have an important implication in the development of small molecules to inhibit infection by a broad range of HIV-1 for the purpose of HIV treatment and prevention.

Electronic supplementary material

The online version of this article (doi:10.1186/s12977-017-0369-y) contains supplementary material, which is available to authorized users.

Serum YKL-40 level is correlated with apnea hypopnea index in patients with obstructive sleep apnea sindrome

OBJECTIVE

Obstructive sleep apnea syndrome (OSAS) has been associated with elevated biochemical markers of inflammation. Although the exact mechanism is unknown, both sleep deprivation and hypoxemia are believed to be important causative factors. YKL-40, also known as chitinase-like protein, has been shown to be related to various inflammatory conditions including atherosclerosis, diabetes, cancer, and asthma. The present study aimed to evaluate the relationship between YKL-40 levels and the Apnea Hypopnea Index (AHI) in patients with obstructive sleep apnea syndrome.

PATIENTS AND METHODS

The study was conducted at the Sleep Unit of the Namik Kemal University Research Center. From January 2013 to December 2013, 120 patients diagnosed with OSAS by polysomnography and 40 subjects without OSAS were recruited. Patients in both groups were matched by age, sex, and body mass index (BMI). They were further divided into groups of mild, moderate and severe OSAS based on their AHI value. Serum YKL-40 concentrations were measured by the enzyme-linked immunosorbent assay (ELISA).

RESULTS

OSAS patients showed significantly elevated YKL-40 levels compared to the control group; 102,05 (23.14) pg/ml in the control group vs. 144.81 (65.53) pg/ml in the OSAS group. A Spearman correlation analysis showed that serum YKL-40 levels were significantly and positively correlated with AHI (r = 0.434, p < 0.001) and oxygen desaturation index (r = 0.374, p < 0.001).

CONCLUSIONS

The study demonstrated that high serum YKL-40 levels correlated with the severity of OSAS and might serve as a nonspecific biomarker for prediction and progression of the disease.

Rational design of low immunogenic anti CD25 recombinant immunotoxin for T cell malignancies by elimination of T cell epitopes in PE38

LMB-2, is a potent recombinant immunotoxin (RIT) that is composed of scFv antibody that targets CD25 (Tac) and a toxin fragment (PE38). It is used to treat T cell leukemias and lymphomas. To make LMB-2 less immunogenic, we introduced a large deletion in domain II and six point mutations in domain III that were previously shown to reduce T cell activation in other RITs. We found that unlike other RITs, deletion of domain II from LMB-2 severely compromised its activity. Rather than deletion, we identified T cell epitopes in domain II and used alanine substitutions to identify point mutations that diminished those epitopes. The novel RIT, LMB-142 contains a 38kDa toxin and nine point mutations that diminished T cell response to the corresponding peptides by an average of 75%. LMB-142 has good cytotoxic activity and has lower nonspecific toxicity in mice. LMB-142 should be more efficient in cancer therapy because more treatment cycles can be given.

RETRACTED: Efficacy and Safety of Induction Dosing of Vedolizumab for Reducing Biliary Inflammation in Primary Sclerosing Cholangitis (Psc) in Individuals with Inflammatory Bowel Disease

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). The abstract authors and presenters of PS124 - EFFICACY AND SAFETY OF INDUCTION DOSING OF VEDOLIZUMAB FOR REDUCING BILIARY INFLAMMATION IN PRIMARY SCLEROSING CHOLANGITIS (PSC) IN INDIVIDUALS WITH INFLAMMATORY BOWEL DISEASE submitted and presented at ILC 2016 have raised concerns that the source data in some cases are inconsistent and requires further evaluation to determine the true magnitude of effect. Hence given the potential impact of this study in PSC at the authors request this abstract, until such time the data can be more completely presented in manuscript form, is being retracted.

The use of short message services (SMS) to provide medical updating to parents in the NICU

OBJECTIVE

Premature delivery and prolonged hospitalization of infants in the neonatal intensive care unit (NICU) are very stressful for parents. As technology has advanced, short message services (SMS) have been used increasingly in the medical disciplines. To date, the use of SMS for updating patients and families regarding medical information has not been reported. We implemented the SMS technique to daily update the parents regarding the health status of their preterm infant. The objective of this study was to evaluate the use of SMS technology and to assess its impact on the parents and the nursing staff.

STUDY DESIGN

Parents and nurses completed questionnaires at two time periods: pre-SMS implementation (pre-SMSi) and post-SMS implementation (post-SMSi). The parent questionnaires included statements about medical information delivery, communication and trust between parents and medical staff, parental anxiety and overall satisfaction. The nurse questionnaires included statements about the expected and actual impact on their workload.

RESULTS

Comparison of the parents' responses at the two time periods indicated that in the post-SMSi time period, they felt that the physician was more available when needed (P=0.002), they were more comfortable about approaching the physician (P=0.001) and more satisfied with the medical information provided by the staff (P=0.03). In the post-SMSi period, 78.1% of the nurses noted that the SMS communication is a convenient and user-friendly method.

CONCLUSIONS

SMS updating is an easy and user-friendly technology that enriches the modalities of information delivery to parents of hospitalized preterm infants. It is a complementary and useful tool for encouraging and improving personal communication between parents and medical staff and should be considered part of quality improvement in health care.

Protection of the Furin Cleavage Site in Low-Toxicity Immunotoxins Based on Pseudomonas Exotoxin A

Recombinant immunotoxins (RITs) are fusions of an Fv-based targeting moiety and a toxin. Pseudomonas exotoxin A (PE) has been used to make several immunotoxins that have been evaluated in clinical trials. Immunogenicity of the bacterial toxin and off-target toxicity have limited the efficacy of these immunotoxins. To address these issues, we have previously made RITs in which the Fv is connected to domain III (PE24) by a furin cleavage site (FCS), thereby removing unneeded sequences of domain II. However, the PE24 containing RITs do not contain the naturally occurring disulfide bond around the furin cleavage sequence, because it was removed when domain II was deleted. This could potentially allow PE24 containing immunotoxins to be cleaved and inactivated before internalization by cell surface furin or other proteases in the blood stream or tumor microenvironment. Here, we describe five new RITs in which a disulfide bond is engineered to protect the FCS. The most active of these, SS1-Fab-DS3-PE24, shows a longer serum half-life than an RIT without the disulfide bond and has the same anti-tumor activity, despite being less cytotoxic in vitro. These results have significance for the production of de-immunized, low toxicity, PE24-based immunotoxins with a longer serum half-life.

Abstract 2976: Engineering next-generation anti-CD25 immunotoxins with improved cytotoxic activity and low immunogenicity

Objective: CD25 is expressed on many T cell malignancies, including adult T cell leukemia, and is a target for cancer therapy. Immunotoxins against CD25+ cells containing a portion of Pseudomonas exotoxin A (PE38) show extremely high cytotoxic activity. Our lab has previously created a de-immunized PE immunotoxin in which toxin domain II was removed. Removal of domain II confers two major advantages: i) the immunogenic sequences found in domain II are removed, generating a less immunogenic toxin; ii) the non-specific toxicity of domain II-truncated toxins is much lower, allowing much higher doses of immunotoxin to be given safely (7-10-fold higher safe dosage). However, removal of domain II, which does not affect or enhances the cytotoxic activity of immunotoxins targeting the B cell marker CD22 or the mesothelioma marker mesothelin, lowers the activity of anti-CD25 immunotoxins 30-fold. Because lowering toxin immunogenicity and animal toxicity are critical for the success of immunotoxins in a clinical setting, we have engineered domain II truncated immunotoxins with improved activity against CD25+ cells using a novel adaptation of an established screening system.

Methods: Eighteen domain II truncation mutants were designed based upon the crystal structure of the toxin. To bypass the resource intensive protein refolding of standard immunotoxins, these domain II mutants were expressed as fusions with the ZZ protein, which is a small (13.6kD) derivative of protein A. Fusion to ZZ allowed easy production of these ZZ-domain II mutant fusion proteins in the E. coli periplasm and fast purification using IgG coated beads. The purified ZZ-domain II mutant toxins were then bound to anti-CD25 IgG by mixing (the ZZ-domain binds human Fc) and tested for cytotoxic activity on the CD25+ T-cell leukemia HUT-102 cell line. The most active domain II mutants were made into standard recombinant immunotoxins and retested.

Results: Of the 18 tested ZZ-domain II mutants, 6 were completely inactive, 8 were active at near parental levels, and 4 were as active as the parental toxin. The 4 high-activity and 2 structurally-interesting, medium-activity mutants were then produced as standard recombinant immunotoxins and retested for cytotoxic activity. Two of the 4 high-activity mutants showed a 2-4-fold increase in activity compared to parental domain II truncated immunotoxin. While still being 8-fold less active than immunotoxins containing domain II (PE38), these high-activity mutant immunotoxins will most likely have lower immunogenicity than toxins with PE38 and much less non-specific toxicity, allowing higher doses and more treatment cycles to be given. Our engineered high-activity domain II mutant immunotoxins are improved candidates for treating CD25+ cancers and for eliminating regulatory immunosuppressive T cells.

Citation Format: Gilad Kaplan, Fred Lee, Ira Pastan. Engineering next-generation anti-CD25 immunotoxins with improved cytotoxic activity and low immunogenicity. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2976.

The joint association of self-rated health and diabetes status on 14-year mortality in elderly men and women

PURPOSE

Low self-rated health (SRH) has been found to be associated with increased risk of type 2 diabetes (T2D) and with mortality. We examined the possible interaction between SRH and diabetic state on all-cause mortality in a large cohort of elderly subjects, followed for 14 years.

METHODS

During the years 2000-2004, survivors of the nationwide longitudinal Israel Study of Glucose Intolerance, Obesity and Hypertension were interviewed and examined for the third follow-up. The 1037 participants (mean age 72.4 ± 7.2 years) were asked to rate their health as: excellent, good, fair, poor, or very poor. Glucose categories were as follows: Normoglycemic, Prediabetes, T2D and Undiagnosed diabetes. Survival time was defined as the time from interview to date of death or date of last vital status follow-up (August 1, 2013). Multivariate Cox proportional hazards models were performed in order to assess whether SRH interacts with glycemic state in the association with mortality.

RESULTS

A better SRH was reported by those with undiagnosed than known diabetes, and best for normoglycemic and prediabetic individuals. While all individuals with fair or poor/very poor SRH were at increased risk of mortality compared to those with excellent/good SRH, in the known diabetic individuals a greater hazard was observed in the excellent/good SRH (HR 3.32, 95 % CI 1.71-6.47) than in those with fair or poor/very poor SRH (HR 2.19, 95 % CI 1.25-3.86), after adjusting for age, sex, ethnic origin, marital status, education, BMI, physical activity, CVD, tumors, and creatinine level (p for interaction = 0.01).

CONCLUSIONS

Self-rated health is not a sensitive tool for predicting mortality in elderly men and women with known T2D.