HLA-DQA1*05 Carriage Associated With Development of Anti-Drug Antibodies to Infliximab and Adalimumab in Patients With Crohn's Disease

IQ Survey Results on Current Industry Practices-Part 1: Immunogenicity Risk Assessment

An immunogenicity risk assessment (IRA) is a relatively new expectation of health authorities that is increasingly incorporated into the drug development process across the pharmaceutical/biotech industry. The guiding principle for an IRA includes a comprehensive evaluation of product- and patient-related factors that may influence the immunogenic potential of a biotherapeutic drug and a potential action plan. The Immunogenicity Working Group from the IQ Consortium (Clinical Pharmacology Leadership Group) has conducted a survey to understand the current practices for conducting IRAs and relevant aspects of bioanalysis. Survey results were provided by 19 IQ member companies participating in the Clinical Pharmacology Leadership Group (CPLG) and the Translational and ADME Sciences Leadership Group (TALG). Nearly all the respondents reported experience with monoclonal antibodies (mAb), with 10 other drug modalities including bioengineered protein therapeutics such as fusion and multi-domain proteins, peptides, oligonucleotides as well as gene and cell therapies. The survey results demonstrate that most companies have a defined IRA process, and there was a common understanding that the IRA may need to be revised as more information becomes available or the drug development strategy changes. Some differences found across the respondents are related to the time frame for implementation of IRA document, the types of preclinical data and computational methods used to assess risk, and how the IRA informs clinical plans and documentation practices. These results highlight that while there have been widespread insights gained with performing IRA for mAbs, more experience is needed to perform IRAs for the novel modalities.

Ancestral Diversity in Pharmacogenomics Affects Treatment for Hispanic/Latine Populations With Inflammatory Bowel Disease

BACKGROUND AND AIMS

The prevalence of inflammatory bowel disease among Hispanic/Latine communities is increasing. Pharmacogenomic studies reveal genetic markers that influence treatment decisions. The aim of our study was to examine the frequency and impact of genetic polymorphisms on thiopurine-associated leukopenia (NUDT15, TPMT) and anti-tumor necrosis factor (TNF) immunogenicity (HLA-DQA1∗05) in a cohort of Hispanic patients of diverse ancestral backgrounds.

METHODS

We performed a multicenter, retrospective cohort study comprising 2225 Hispanic participants. We measured the frequency of variation affecting drug response in NUDT15, TPMT, and HLA-DQA1∗05; their ancestral origin (European, African, or Amerindian); and the rate of development of myelosuppression and immunogenicity to thiopurines and anti-TNFs, in exposed patients.

RESULTS

NUDT15 and TPMT variants were rare, except for rs116855232 in NUDT15, which was common only in alleles of Amerindian origin. All NUDT15 variant alleles were inherited on an Amerindian haplotype, and among the Amerindian allele subset, the variant frequency of NUDT15∗4 (rs147390019) was a remarkable 23% in patients with leukopenia but only 3% in patients without leukopenia. HLA-DQA1∗05 and its European tagging variant rs2097432 were common in alleles from all ancestral origins and demonstrated association with immunogenicity to anti-TNFs. However, rs2097432 was only correlated with HLA-DQA1∗05 in the European allele subset.

CONCLUSIONS

These findings indicate that NUDT15 testing should become standard clinical practice before prescribing thiopurines in individuals with Amerindian/Alaska Native ancestry, including Hispanic individuals. Additionally, rs2097432 should not be used as a surrogate for HLA-DQA1∗05 testing for diverse populations. Ultimately, incorporating ancestry in personalized therapeutic approaches is important for treatment of Hispanic patients with inflammatory bowel disease.

HLA DQA1*05 and Risk of Antitumor Necrosis Factor Treatment Failure and Anti-Drug Antibody Development in Children With Crohn's Disease

INTRODUCTION

Human leukocyte antigen (HLA) DQA1*05 has been associated with the development of anti-drug antibodies (ADA) to tumor necrosis factor antagonists (anti-TNFα) and treatment failure among adults with Crohn's disease (CD). However, findings from other studies have been inconsistent with limited pediatric data.

METHODS

We analyzed banked serum from patients with CD aged <21 years enrolled in clinical outcomes of Methotrexate Binary Therapy in practice, a multicenter, prospective randomized trial of anti-TNFα monotherapy vs combination with methotrexate. The primary outcome was a composite of factors indicative of treatment failure. The secondary outcome was ADA development.

RESULTS

A trend toward increased treatment failure among HLA DQA1*05-positive participants was not significant (hazard ratio 1.58, 95% confidence interval [CI] 0.95-2.62; P = 0.08). After stratification by HLA DQA1*05 and by methotrexate vs placebo, patients who were HLA DQA1*05 negative and assigned to methotrexate experienced less treatment failures than HLA DQA1*05-positive patients on placebo (hazard ratio 0.31, 95% CI 0.13-0.70; P = 0.005). A trend toward increased ADA development among HLA DQA1*05-positive participants was not significant (odds ratio 1.96, 95% CI 0.90-4.31, P = 0.09). After further stratification, HLA DQA1*05-negative participants assigned to methotrexate were less likely to develop ADA relative to HLA DQA1*05-positive patients on placebo (odds ratio 0.12, 95% CI 0.03-0.55; P = 0.008).

DISCUSSION

In a randomized trial of children with CD initiating anti-TNFα, 40% were HLA DQ-A1*05 positive, which was associated with a trend toward increased risk of both treatment failure and ADA. These risks were mitigated, but not eliminated, by adding oral methotrexate. HLA DQ-A1*05 is an important biomarker for prognosis and risk stratification.

Predictors of Immunogenicity and Loss of Response to ANTI-TNFα Therapy in Crohn Disease-A Systematic Review

BACKGROUND

As the use of anti-tumor necrosis factor-α (TNFα) therapies in Crohn disease (CD) is spread, the loss-of-response (LOR) to it is increasingly encountered. Discovering a pathological pathway and biomarkers that can predict LOR would assist in the management of patients with CD. In this article, we provide a comprehensive systematic review of studies assessing predictors of immunogenicity and loss-of-response to anti-TNFα drugs in patients with CD.

DATA SOURCES

We performed a systematic review of PubMed to identify citations pertaining to predictors of immunogenicity and loss-of-response to anti-TNFα drugs in patients with CD through April 27, 2024, using a predefined string of keywords. Data extraction and quality assessment were performed independently by 2 reviewers.

RESULTS

A total of 18 eligible studies were included in the review. Four major groups of studies were identified: genetic factors, factors linked with colonic inflammation, serum and anthropological markers, and prevention of LOR. Promising predictors of LOR to infliximab or adalimumab include the carriage of HLA-DQA1*05, visceral adiposity, intestinal abundant presence of CD96, IL-17, and IL-23. Substantial heterogeneity was observed, and none of the markers had undergone formal validation. Specific limitations to acceptance of these factors included failure to use a standardized definition of LOR to anti-TNFα treatment, lack of specificity, and insufficient relevance to the pathogenesis of LOR.

CONCLUSIONS

This review underlines the lack of well-defined studies and controlled trials investigating predictors of LOR to anti-TNFα therapies in CD. A research priority is the development of reliable and accurate biomarkers that can shed light on the pathogenesis of the implied LOR. These biomarkers, along with genetic factors, have the potential to enhance clinical management by aiding in patient stratification and monitoring.

A Bottom-Up Liquid Chromatography-Tandem Mass Spectrometry Method for Therapeutic Drug Monitoring of Infliximab: Method Development, Comparison With 2 Enzyme-Linked Immunosorbent Assay Methods, and Evaluation of Anti-Drug Antibody Interference

CONTEXT.—

Therapeutic drug monitoring is recommended to optimize infliximab use and improve outcome in chronic inflammatory disorders.

OBJECTIVE.—

To describe a simple and affordable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to measure infliximab in serum.

DESIGN.—

Infliximab was measured using winged stable isotope-labeled peptides as internal standards. Linearity, lower limit of measuring interval, limit of detection, precision, accuracy, carryover, and ion suppression were evaluated. Method comparison against 2 enzyme-linked immunosorbent assay (ELISA) methods (Remsima Monitor and IDKmonitor Infliximab) and anti-drug antibody (ADA) interference were evaluated using clinical specimens from inflammatory bowel disease patients (N = 237).

RESULTS.—

Analytical run time and sample preparation time were 5 minutes per sample and 3 hours per batch, respectively. Analytical measurement interval and limit of detection were 0.50 to 50.0 μg/mL (R2 = 0.998) and 0.25 μg/mL, respectively. The intraday and interday imprecision percentage coefficients of variation were less than 6.1%. Accuracy was 94.2% to 98.7%. No significant ion suppression or carryover was observed. Infliximab concentrations measured by LC-MS/MS showed good agreement with those measured by Remsima Monitor (mean percentage difference, 5.7%; 95% CI, -1.2% to 12.6%) but were markedly lower than those measured by IDKmonitor (-32.6%; -35.8% to -29.4%), demonstrating significant bias between ELISAs. Although a good agreement between LC-MS/MS and ELISA was observed for ADA-negative samples (-3.5%; -12.8% to 5.9%), a significant bias was observed for ADA-positive samples (13.6%; 1.7% to 25.6%).

CONCLUSIONS.—

This simple, fast, and affordable LC-MS/MS method for infliximab quantitation could improve standardization of infliximab quantitation and optimization of infliximab use in patients with high-titer ADA.

Comparing Outcomes With Subcutaneous Infliximab (CT-P13 SC) by Baseline Immunosuppressant Use: A Post Hoc Analysis of the LIBERTY-CD and LIBERTY-UC Studies

BACKGROUND

Superior efficacy of subcutaneous infliximab (CT-P13 SC) over placebo for maintenance therapy in patients with Crohn's disease (CD) and ulcerative colitis (UC) was demonstrated in the randomized LIBERTY-CD and LIBERTY-UC studies. The current post hoc analysis compared outcomes with CT-P13 SC by baseline immunosuppressant use.

METHODS

Patients with moderately to severely active CD or UC randomized to the CT-P13 SC maintenance arm of the 54-week LIBERTY trials at week 10 and who were treated in the open-label extension (weeks 56-102) were included. Pharmacokinetic, efficacy, biomarker, safety, and immunogenicity endpoints were evaluated by baseline immunosuppressant use (monotherapy vs combination therapy).

RESULTS

A total of 192 patients with CD (monotherapy, n = 126; combination therapy, n = 66) and 237 patients with UC (monotherapy, n = 180; combination therapy, n = 57) were included. In both studies, efficacy outcomes were generally comparable between monotherapy and combination therapy at week 54 or week 102. Serum concentrations were generally higher, and antidrug antibody-positive conversion rates were lower, with combination therapy relative to monotherapy. In combined analyses of CD and UC, comparable safety profiles were observed between monotherapy and combination therapy.

CONCLUSIONS

Despite some differences in pharmacokinetics and immunogenicity between CT-P13 SC received alone or in combination with immunosuppressants in patients with CD or UC, efficacy outcomes at week 54 or week 102 were generally comparable. The overall safety profile and incidence of systemic injection reactions were also comparable between monotherapy and combination therapy.

HLA-DQA1*05 Allele Carriage and Anti-TNF Therapy Persistence in Inflammatory Bowel Disease

INTRODUCTION

Carriage of the HLA-DQA1*05 allele is associated with development of antidrug antibodies (ADAs) to antitumor necrosis factor (anti-TNF) therapy in patients with Crohn's disease. However, ADA is not uniformly associated with treatment failure. We aimed to determine the impact of carriage of HLA-DQA1*05 allele on outcome of biologic therapy evaluated by drug persistence.

METHODS

A multicenter, retrospective study of 877 patients with inflammatory bowel disease (IBD) treated with anti-TNF therapy with HLA-DQA1*05 genotypes were generated by imputation from whole genome sequence using the HIBAG package, in R. Primary end point was anti-TNF therapy persistence, (time to therapy failure), segregated by HLA-DQA1*05 allele genotype and development of a risk score to predict anti-TNF therapy failure, incorporating HLA-DQA1*05 allele genotype status (LORisk score).

RESULTS

In all, 877 patients receiving anti-TNF therapy were included in our study; 543 (62%) had no copy, 281 (32%) one copy, and 53 (6%) 2 copies of HLA-DQA1*05 allele. Mean time to anti-TNF therapy failure in patients with 2 copies of HLA-DQA1*05 allele was significantly shorter compared with patients with 0 or 1 copy at 700 days' follow-up: 418 vs 541 vs 513 days, respectively (P = .012). Factors independently associated with time to anti-TNF therapy failure included carriage of HLA-DQA1*05 allele (hazard ratio [HR], 1.2, P = .02; female gender HR, 1.6, P < .001; UC phenotype HR, 1.4, P = .009; and anti-TNF therapy type [infliximab], HR, 1.5, P = .002). The LORisk score was significantly associated with shorter time to anti-TNF therapy failure (P < .001).

CONCLUSIONS

Carriage of 2 HLA-DQA1*05 alleles is associated with less favorable outcomes for patients receiving anti-TNF therapy with shorter time to therapy failure. HLA-DQA1*05 genotype status in conjunction with clinical factors may aid in therapy selection in patients with IBD.

Exploring the genetic components and multi-omics sources of inflammatory bowel disease from the perspective of autoimmune disorders

BACKGROUND

Inflammatory bowel disease (IBD) and autoimmune disorders result from immune system dysregulation. However, the genetic overlap between them remains unclear. Our study aimed to investigate the genetic mechanisms and structure of IBD from the perspective of autoimmune disorders.

METHODS

The genetic correlation (rg) between traits can provide valuable information about the shared underlying biological mechanisms. Utilizing summary statistics from genome-wide association studies, we delved into the genetic correlation, shared inheritance, and potential causality of IBD (N = 34,652) with autoimmune disorders (N = 1,755,610). We performed transcriptomics at the gene level, multi-marker analyses of genome annotations, and enrichment analyses of biological pathways to highlight shared and diverse perspectives.

RESULTS

There were significant genetic correlations between IBD and ankylosing spondylitis (rg = 0.327), rheumatoid arthritis (rg = 0.242), type 1 diabetes (rg = - 0.061), psoriasis (rg = 0.246), and ankylosing spondylitis (rg = 0.308). We identified 110 unique regions (including 5p33.3, 10q25.3, and 22q13.31) after a consistent study at the gene levels. By implementing transcriptomics techniques, we discovered potential common biological mechanisms in several tissues, including blood, spleen, thyroid, and pancreas, revealing potential common biological mechanisms involving lincRNA, protein-coding, and pseudogenes.

CONCLUSION

Our study demonstrated hypothesized pleiotropic genomic regions that provide important clues to delve into the genetic basis of IBD and autoimmune disorders on the basis of multi-omics. Moreover, we have identified shared pathogenic processes and potential common therapeutic targets among these diseases. Key Points • The finding provides a new perspective on the genetic basis of inflammatory bowel disease and autoimmune disease across multi-omics platforms. • Fine mapping of functional summary-based imputation and causal genomes has identified hypothesized pleiotropic genomic regions. • The identified genes and pathways may offer innovative targets for the prevention of immune-related diseases.

Genetic polymorphisms impacting clinical pharmacology of drugs used to treat inflammatory bowel disease: a precursor to multi-omics approach to precision medicine

INTRODUCTION

Inflammatory bowel diseases (IBDs), comprised of ulcerative colitis (UC) and Crohn's disease (CD), are chronic inflammatory diseases of the gastrointestinal tract. Clinicians and patients must vigilantly manage these complex diseases over the course of the patient's lifetime to mitigate risks of the disease, surgical complications, progression to neoplasia, and complications from medical or surgical therapies. Over the past several decades, the armamentarium of IBD therapeutics has expanded; now with biologics and advanced small molecules complementing conventional drugs such as aminosalicylates, corticosteroids and thiopurines. Significant attention has been paid to the potential of precision medicine to assist clinicians in tailoring therapeutics based on patients' genetic signatures to maximize therapeutic benefit while minimizing adverse effects.

AREAS COVERED

In this paper, we review the published literature on genetic polymorphisms relevant to each class of IBD therapeutics.

EXPERT OPINION

Finally, we envision a paradigm shift in IBD research toward an omics-based network analysis approach. Through global collaboration, organization and goal setting, we predict the next decade of IBD research will revolutionize existing disease frameworks by developing precise molecular diagnoses, validated biomarkers, predictive models and novel molecularly targeted therapeutics.

Measurement of Anti-TNF Biologics in Serum Samples of Pediatric Patients: Comparison of Enzyme-Linked Immunosorbent Assay (ELISA) with a Rapid and Automated Fluorescence-Based Lateral Flow Immunoassay

Background: Therapeutic drug monitoring (TDM) of infliximab (IFX) and adalimumab (ADL) mainly relies on the use of enzyme-linked immunosorbent assays (ELISA). More recently, rapid assays have been developed and validated to reduce turnaround time (TAT). Here, we compared IFX and ADL concentrations measured with both ELISA and a new fluorescence-based lateral flow immunoassay (AFIAS). Methods: In serum samples from pediatric patients, IFX and ADL drug levels, and total anti-IFX antibodies were measured using clinically validated ELISA kits (Immundiagnostik AG). Samples were further analyzed using a new rapid assay (AFIAS, Boditech Med Inc.) to measure drug levels and total anti-IFX antibodies. Results: Spearman's correlation coefficients (rho) were 0.98 [95% confidence interval (CI) 0.97 to 0.99] for IFX (p < 0.001) and 0.83 (95% CI 0.72 to 0.90) for ADL (p < 0.001). Calculated % bias was -14.09 (95% Limits of agreement, LoA, -52.83 to 24.66) for IFX and 15.79 (LoA -37.14 to 68.73) for ADL. For the evaluation of total anti-IFX antibodies, we did not collect sufficient data to establish a statistically significant correlation between AFIAS and ELISA. The inter-rater agreement showed a "substantial" and a "moderate" agreement for IFX and ADL, respectively. Conclusions: Our results show that the AFIAS assay has an accuracy and analytical performance comparable to that of the ELISA method used for TDM of IFX and ADL. Therefore, the introduction of this device into routine clinical practice could provide results more quickly and with similar accuracy as ELISA, allowing clinicians to rapidly formulate clinical decisions.

The first WHO reference panel for Infliximab anti-drug antibodies: a step towards harmonizing therapeutic drug monitoring

Immunogenicity testing for anti-drug antibodies (ADA) is mandatory for regulatory approval of a biotherapeutic and can, in some instances, continue post-licensure. Typical examples are TNF inhibitors where biotherapeutic and ADA levels are relevant in clinical decision-making for optimal patient therapy. However, challenges with non-comparability of results due to plethora of bioanalytical techniques and the lack of standardization has hindered ADA monitoring in clinical practice. Two human anti-infliximab monoclonal antibodies (A, B) with defined characteristics were therefore lyophilized and assessed for suitability as a reference panel for ADA assays in an international study. Binding assays included the simple ELISA and common electrochemiluminescence (ECL) to the rare antigen binding test and lateral flow assays. For neutralisation, competitive ligand binding and reporter-gene assays were employed. Sample testing (e.g., antibodies, sera) showed differential reactivity depending on the assay and sample. Estimates for ADA levels using in-house standards varied substantially among assays/laboratories. In contrast, using antibody A for quantitating ADA levels reduced the interlaboratory variability and provided largely consistent estimates. The degree of harmonization was dependent on the assay, sample and the laboratory. Importantly, antibody A allowed ADA detection when missed using in-house standards. Recognition of sample B varied, possibly due to its fast dissociation. Overall, the panel comprising A (coded 19/234) and B (coded 19/232) was suitable and established by the WHO Expert Committee on Biological Standardization in October 2022 as the WHO international reference panel for infliximab ADA assays. Sample A (coded 19/234) with an arbitrarily assigned unitage of 50,000IU/ampoule for binding activity and 50,000 IU/ampoule for neutralising activity is intended as a 'common standard' for assay characterization and where possible for calibration of anti-infliximab preparations to facilitate comparison and harmonization of results across infliximab ADA assays. Sample B (19/232) with its unique characteristics and variable detection but no assigned unitage is intended for assessing the suitability of the assay for detecting ADAs with fast dissociation. It is anticipated that this panel would help towards selecting and characterizing suitable assays, benchmarking of in-house standards where feasible and in harmonizing ADA assays used in clinical practice for better patient outcome globally.

Genetic factors that predict response and failure of biologic therapy in inflammatory bowel disease

Inflammatory bowel disease (IBD) represents a significant disease burden marked by chronic inflammation and complications that adversely affect patients' quality of life. Effective diagnostic strategies involve clinical assessments, endoscopic evaluations, imaging studies, and biomarker testing, where early diagnosis is essential for effective management and prevention of long-term complications, highlighting the need for continual advancements in diagnostic methods. The intricate interplay between genetic factors and the outcomes of biological therapy is of critical importance. Unraveling the genetic determinants that influence responses and failures to biological therapy holds significant promise for optimizing treatment strategies for patients with IBD on biologics. Through an in-depth examination of current literature, this review article synthesizes critical genetic markers associated with therapeutic efficacy and resistance in IBD. Understanding these genetic actors paves the way for personalized approaches, informing clinicians on predicting, tailoring, and enhancing the effectiveness of biological therapies for improved outcomes in patients with IBD.

The Role of Human Leukocyte Antigen Alleles and Maternal Microchimerism in Very-Early-Onset Ulcerative Colitis in Japanese Children

BACKGROUND

Very-early-onset ulcerative colitis (VEO-UC) is a severe form of inflammatory bowel disease that manifests before the age of 6 years. Compared to typical pediatric UC, it is characterized by distinct genetic and immunological factors. This study aimed to investigate the roles of specific human leukocyte antigen (HLA) alleles and maternal microchimerism (MMc) in the pathogenesis of VEO-UC in a Japanese population.

METHODS

This study included 27 VEO-UC patients, including 4 patients treated with colorectal resection. HLA typing was performed by polymerase chain reaction-sequence-specific oligonucleotide probing (PCR-SSOP) and compared with the Japanese general population. Immunohistochemistry and fluorescence in situ hybridization were used to evaluate MMc in intestinal tissues. Statistical comparisons of HLA were performed against data from the general Japanese population, with Bonferroni corrections applied to handle multiple comparisons.

RESULTS

HLA-B52 and HLA-DR15 were more prevalent in cases of VEO-UC than in the general Japanese population, although the statistical significance decreased after the Bonferroni correction. MMc was found in the intestinal tissues of three VEO-UC cases, whereas it was absent in the control UC cases. Maternal HLA concordance with specific alleles associated with VEO-UC was noted in several cases, suggesting maternal immune involvement in the pathogenesis of the disease.

CONCLUSIONS

VEO-UC seems to share genetic traits with adult UC, such as an association with HLA-B52 and HLA-DR15, and is also affected by maternal immune contributions, as shown by the presence of MMc in the affected tissues. These findings highlight the complex interaction between genetic and immunological factors in the pathogenesis of VEO-UC and underscore the need for further research to develop targeted therapeutic strategies that address these mechanisms.

Pharmacogenetics in Response to Biological Agents in Inflammatory Bowel Disease: A Systematic Review

Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders influenced by microbial, environmental, genetic, and immune factors. The introduction of biological agents has transformed IBD therapy, improving symptoms, reducing complications, and enhancing patients' quality of life. However, approximately 30% of patients exhibit primary non-response, and 50% experience a loss of response over time. Genetic and non-genetic factors contribute to variability in treatment outcomes. This systematic review aims to thoroughly analyze and assess existing studies exploring the relationships between genetic variations and individual responses to biologic drugs, in order to identify genetic markers that are predictive of treatment efficacy, risk of adverse effects, or drug toxicity, thereby informing clinical practice and guiding future research. PubMed and EMBASE papers were reviewed by three independent reviewers according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses [PRISMA] guidelines. Of the 883 records screened, 99 met the inclusion criteria. The findings of this review represent an initial step toward personalized medicine in IBD, with the potential to improve clinical outcomes in biological therapy.

Age as a Predictor of Serum Tumor Necrosis Factor Antagonist Drug and Antidrug Antibody Concentrations in Inflammatory Bowel Disease-A Nationwide Cohort Study

Background/Objectives: Tumor necrosis factor antagonists (anti-TNFs) have been shown to be an effective treatment for inflammatory bowel disease (IBD). Several factors are associated with anti-TNF treatment failure. This study aims to explore the impact of age on serum concentrations of anti-TNF drugs and antidrug antibodies (ADAbs). Methods: We retrospectively reviewed patients' charts from July 2018 until September 2024 across seven medical centers. Patients with an established diagnosis of IBD receiving infliximab or adalimumab were included. The primary outcome of this study was the effect of age on the anti-TNFs serum drug concentration and ADAb levels. Linear regression was performed to explore the relationship between age and serum anti-TNF drug and ADAb levels. Results: 1093 patients were included in our cohort. In patients receiving infliximab, there was a significant association between older age and increasing ADAbs levels (p = 0.036), whereas in patients treated with adalimumab, there was no significant relationship between older age and ADAb levels (p = 0.771). There was no significant relationship between age and adalimumab serum concentration (p = 0.54). When stratified by age, patients taking infliximab who were >30 years of age developed more ADAbs compared to those aged ≤30 (p = 0.003). Conclusions: Patients older than 30 years of age receiving infliximab monotherapy have higher ADAbs and lower serum drug concentrations than younger patients. There was no statistically significant difference in ADAbs and serum drug concentrations among patients receiving infliximab combination therapy or adalimumab monotherapy.

Lipid-Rapamycin Nanovaccines Overcome the Antidrug Antibody Barrier in Biologic Therapies

Antidrug antibodies (ADAs) against biologics present a major challenge for sustained biotherapy, including enzyme replacement therapies and adeno-associated virus (AAV) gene therapies. These antibodies arise from undesirable immune responses, leading to altered pharmacokinetics, reduced efficacy, and adverse reactions. In this study, we introduced a rationally designed lipid-rapamycin (Rapa)-based nanovaccine to restore immune tolerance to biologics and overcome drug resistance. The nanovaccine significantly decreased ADA responses when used in a tolerogenic regimen with keyhole limpet hemocyanin (KLH), uricase, pegylated uricase, and AAV8 vector gene therapy. This approach facilitated three rechallenges with pegylated uricase after a 5 week rest from the nanovaccine, thereby enhancing its urate-lowering efficacy. Furthermore, the nanovaccine allowed for the successful intravenous readministration of AAV8 vector expressing secreted embryonic alkaline phosphatase (AAV8-SEAP), achieving sustained viral DNA and transcript levels in target tissues. The nanovaccine prompted antigen-presenting cells (APCs) in the liver to exhibit dynamic changes in CD80, CD86, MHCII, and PD-L1, which promoted the development of immunoregulatory T cells in response to biologic challenges. Notably, the nanovaccine exerted a minimal impact on CD8+ T cells, natural killer (NK) cells, and NK T cells, preserving the body's normal immune response to pathogens and tumors. Overall, the universal nanovaccine addressed biologic resistance by mitigating ADA-related issues, thereby enabling a prolonged therapeutic efficacy for antibodies, proteins, and gene therapies.

Understanding the therapeutic toolkit for inflammatory bowel disease

Inflammatory bowel disease (IBD), encompassing ulcerative colitis and Crohn's disease, is a group of chronic, immune-mediated disorders of the gastrointestinal tract that present substantial clinical challenges owing to their complex pathophysiology and tendency to relapse. A treat-to-target approach is recommended, involving iterative treatment adjustments to achieve clinical response, reduce inflammatory markers and achieve long-term goals such as mucosal healing. Lifelong medication is often necessary to manage the disease, maintain remission and prevent complications. The therapeutic landscape for IBD has evolved substantially; however, a ceiling on therapeutic efficacy remains and surgery is sometimes required (owing to uncontrolled disease activity or complications). Effective IBD management involves comprehensive care, including medication adherence and a collaborative clinician-patient relationship. This Review discusses current therapeutic options for IBD, detailing mechanisms of action, efficacy, safety profiles and guidelines for use of each drug class. We also explore emerging therapies and the role of surgery. Additionally, the importance of a multidisciplinary team and personalized care in managing IBD is emphasized, advocating for patient empowerment and involvement in treatment decisions. By synthesizing current knowledge and emerging trends, this Review aims to equip healthcare professionals with a thorough understanding of therapeutic options for IBD, enhancing informed, evidence-based decisions in clinical practice.

Comprehensive care of ulcerative colitis: new treatment strategies

INTRODUCTION

Ulcerative colitis is a chronic inflammatory condition of the colon driven by aberrant immune activation. Although advanced medical therapies form the cornerstone of ulcerative colitis management, unmet needs include failure to induce and sustain remission in a substantial proportion of patients and in managing acute severe ulcerative colitis. We review new treatment strategies that might improve patient outcomes in the management of moderate-to-severe ulcerative colitis.

AREAS COVERED

A literature search was conducted using the PubMed database, including studies published from inception to October 2024, selected for their relevance. Recognizing current limitations, this article reviews strategies to improve treatment outcomes in ulcerative colitis using advanced therapies. These approaches include early treatment initiation, dose optimization, positioning newer agents as first-line therapies, combination therapy, targeting novel therapeutic endpoints, and the management of acute severe ulcerative colitis.

EXPERT OPINION

The strategies discussed may contribute to establishing new standards of care aimed at achieving long-term remission and enhancing patient outcomes. Personalized therapy, which tailors treatment based on individual disease characteristics and risk factors, is anticipated to become a critical aspect of delivering more effective care in the future.

Detection of antibodies to infliximab in routine care: a 4-year French retrospective study

Despite its wide use to treat various inflammatory diseases, infliximab becomes ineffective in some patients due to inadequate drug levels and production of anti-drug antibodies (ADA). The aim of this study was to compare the prevalence and ADA levels in a large cohort of patients. ADA and infliximab (IFX) through levels measured by enzyme-linked immunosorbent assay were collected from 505 patients within a period of 4 years. The results indicate that (i) 13.5% of patients produce ADA, (ii) male patients were more likely to produce ADA at levels above 10 000 ng/ml than female patients, (iii) ADA levels were lower when associated with immunosuppressant drugs, (iv) there was an inverse relationship between ADA presence and IFX detection, and (v) no correlation was observed between ADA levels and number of injections or brand of IFX administered. This study improves our understanding of the factors promoting IFX immunogenicity and highlights the need to develop personalized treatment strategies.

Establishment and internal validation of a model to predict the efficacy of Adalimumab in Crohn's disease

BACKGROUND

Clinically, the ability to distinguish which Crohn's disease patients can benefit from Adalimumab is limited.

AIMS

This study aimed to develop a model for predicting clinical remission probability for Crohn's disease patients with Adalimumab at 12 weeks. The model assists clinicians in identifying which Crohn's disease patients are likely to benefit from Adalimumab treatment before starting therapy, thus optimizing individualized treatment strategies.

METHODS

Demographic and clinical characteristics of Crohn's disease patients were utilized to develop a model for clinical remission probability. LASSO regression was used to select predictive factors, and predictions were made using a logistic regression model. The model was internally validated using the bootstrap method (resampling 1000 times).

RESULTS

68 patients with Crohn's disease were enrolled in this study. Clinical remission was observed in 55.9% at 12 weeks. Three variables were selected through the least absolute shrinkage and selection operator regression method, including Adalimumab-positive cell count, disease duration, and neutrophil count of Crohn's disease patients. A predictive model was constructed by multivariate logistic regression (Adalimumab-positive cell count (OR, 1.143; 95%CI, 1.056-1.261), disease duration (OR, 0.967; 95%CI, 0.937-0.986), and neutrophil count (×109/L) (OR, 1.274; 95%CI,1.014-1.734)). The predictive model yielded an area under the curve of 0.866 (95%CI, 0.776-0.956), and in the internal validation, the area under the curve was 0.870 (95%CI, 0.770-0.940).

CONCLUSIONS

This model provides a convenient tool to assess the likelihood of patient remission prior to Adalimumab treatment, thereby supporting the development of personalized treatment plans.

Involvement of HLADQA1*05 in Patients with Inflammatory Bowel Disease Treated with Anti-TNF Drugs

Background: Over the past decade, TNF inhibitors such as Infliximab and Adalimumab have become central to Inflammatory Bowel Diseases treatment, greatly enhancing patient outcomes. However, immunogenicity-where anti-drug antibodies diminish effectiveness-remains an issue, often requiring dose changes or combination therapies. Pharmacogenomics is increasingly applied in IBD to personalise treatment, especially since genetic factors like the HLA-DQA1*05 variant heighten the immunogenicity risk with IFX. This study aims to examine the relationship between the HLA-DQA1*05 variant and response loss or antibody development in patients regularly monitored on IFX or ADA. Methods: Sixty-five paediatric IBD patients were enrolled, with therapeutic drug monitoring (TDM) of IFX and ADA, conducted using immunoenzymatic assays. The presence of the HLA-DQA1*05 T>C allele variant was also tested using a Biomole HLA-DQA1 Real-time PCR kit. Results: The HLA-DQA1*05 rs2097432 T>C allele was present in 54% of patients on IFX and 69% of those on ADA. No statistically significant differences were found between HLA carriers and non-carriers across any of the three analysed groups: IFX, ADA and the overall anti-TNFα. Conclusions: Our study suggests that the HLA-DQA1*05 allele does not increase the risk of secondary loss of response to anti-TNF therapy, likely because most patients were on a combination of anti-TNF agents and immunomodulators, which can lower anti-drug antibody production. Testing for HLA-DQA105 can aid in personalising treatment and optimising therapy to minimise immunogenicity risks.

HLA-DQA1*05 Associates With Anti-Tumor Necrosis Factor Immunogenicity and Low Adalimumab Trough Concentrations in Inflammatory Bowel Disease Patients From the SERENE Ulcerative Colitis and Crohn's Disease Studies

BACKGROUND AND AIMS

Anti-tumor necrosis factor (anti-TNF) therapies are commonly prescribed treatments for Crohn's disease (CD) and ulcerative colitis (UC). Many patients treated with anti-TNF therapy eventually develop anti-drug antibodies (ADAs). Understanding the factors associated with immunogenicity in anti-TNF-treated patients can help guide treatment. The Humira SERENE studies were Phase 3 trials investigating adalimumab induction regimens in CD and UC patients.

METHODS

We imputed alleles for 7 HLA genes in 1100 patients from the SERENE CD and SERENE UC trials. We then tested these alleles for association with time to immunogenicity. Subsequently, we tested loci significantly associated with immunogenicity for their association with patients who had consistently low drug serum concentrations.

RESULTS

This study replicated the association of HLA-DQA1*05 with time to immunogenicity (hazard ratio [HR] 1.42, p = 2.22E-06). Specifically, HLA-DQA1*05:05 was strongly associated (HR 1.76, p = 2.02E-10) and we detected a novel association represented by HLA-DRB1*01:02 (HR 3.16, p = 2.92E-07). Carriage of HLA-DQA1*05:05 and HLA-DRB1*01:02 was associated with patients who experienced consistently low adalimumab trough concentrations (HLA-DQA1*05:05: odds ratio [OR] 1.98, p = 0.0049; HLA DRB1*01:02: OR 7.06, p = 7.44E-05).

CONCLUSIONS

We found a significant association between alleles at genes in the human HLA locus and the formation of adalimumab immunogenicity and low adalimumab drug serum concentrations in large clinical studies of CD and UC patients. This work extends previous findings in CD to UC and directly shows a genetic association in patients with low drug concentrations. This work builds on existing literature to suggest that genetic screening could be a useful tool for clinicians concerned with patient anti-TNF immunogenicity.

CLINICAL TRIAL REGISTRATION NUMBERS

SERENE CD (NCT02065570), SERENE UC (NCT02065622).

Eleven Grand Challenges for Inflammatory Bowel Disease Genetics and Genomics

The past 2 decades have witnessed extraordinary advances in our understanding of the genetic factors influencing inflammatory bowel disease (IBD), providing a foundation for the approaching era of genomic medicine. On behalf of the NIDDK IBD Genetics Consortium, we herein survey 11 grand challenges for the field as it embarks on the next 2 decades of research utilizing integrative genomic and systems biology approaches. These involve elucidation of the genetic architecture of IBD (how it compares across populations, the role of rare variants, and prospects of polygenic risk scores), in-depth cellular and molecular characterization (fine-mapping causal variants, cellular contributions to pathology, molecular pathways, interactions with environmental exposures, and advanced organoid models), and applications in personalized medicine (unmet medical needs, working toward molecular nosology, and precision therapeutics). We review recent advances in each of the 11 areas and pose challenges for the genetics and genomics communities of IBD researchers.

Immunogenicity of Therapeutic Antibodies Used for Inflammatory Bowel Disease: Treatment and Clinical Considerations

The introduction of tumor necrosis factor inhibitors has led to a paradigm shift in the management of inflammatory bowel disease (IBD). The subsequent introduction of both anti-integrins and cytokine blockers has since expanded the biologic armamentarium. However, immunogenicity, defined as the production of anti-drug antibodies (ADAs) to the prescribed biopharmaceutical, means a significant fraction of patients exposed to biologic agents will experience a secondary loss of response to one or more of the drugs. In clinical settings, immunogenicity may be caused by several factors, both patient related (e.g., underlying chronic disease, systemic immune burden, including previous biologic therapy failure, and [epi]genetic background) and treatment related (e.g., dose and administration regimens, drug physical structure, photostability, temperature, and agitation). Here, we outline these elements in detail to enhance biopharmaceutical delivery and therapy for patients with IBD. Moreover, concurrent immunomodulator medication may reduce the risks of ADA generation, especially when using the chimeric drug infliximab. Summarizing the latest developments and knowledge in the field, this review aims to provide strategies to prevent ADA production and information on managing non-responsiveness or loss of response to biologics. Better understanding of the molecular mechanisms underlying the formation of ADAs and the critical factors influencing the immunogenicity of biopharmaceuticals may lead to improved health outcomes in the IBD community that may benefit both the individual patient and society through lower healthcare expenses.

Does HLA-DQA1*05 carriage have a greater impact on the outcome of infliximab therapy for isolated small-bowel Crohn's disease?

Carriage of HLA-DQA1*05 is thought to increase the formation of anti-tumour necrosis factor alpha (TNF-α) antibodies, reducing the drug efficacy in Crohn's disease (CD) patients. However, little data are currently available for small-bowel Crohn's disease (SB-CD). A specific assessment of the impact of HLA-DQA1*05 on the clinical response to treatment with infliximab (IFX), a TNF-α antagonists, in SB-CD patients is necessary. We conducted a single-center retrospective study that included 106 SB-CD patients treated with IFX. The serum samples were collected for antibodies to infliximab (ATI) testing and HLA-DQA1*05 genotyping. Double-balloon enteroscopy (DBE) was performed following the IFX treatment, with endoscopic outcomes evaluated using the partial simple endoscopic score for CD (pSES-CD), whereas the clinical response was assessed with the Crohn's disease activity index (CDAI). Multivariate logistic regression and multivariate COX regression analyses were employed to analyze the correlation of the HLA-DQA1*05 genotypes with other clinical variables. In this study, 30.2% of SB-CD patients carried the HLA-DQA1*05 allele, which significantly increased their risk of ATI generation (odds ratio [OR] = 2.337, p = .043), but it was not associated with the clinical response to IFX and drug persistence (OR = 2.356, p = .145; OR = 0.457, p = .249). The endoscopic remission rates were 40.6% (13/32) and 55.4% (41/74) in HLA-DQA1*05 carriers and non-carriers, respectively. HLA-DQA1*05 was not associated with endoscopic remission (OR = 0.684, p = .414). The HLA-DQA1*05 variant is identified as a significant risk factor of ATI formation in Chinese patients with SB-CD, but is not associated with the clinical response of IFX treatment and endoscopic remission of SB lesions.

Electronic address: clinicalpractice@gastro.org. AGA Living Clinical Practice Guideline on Pharmacological Management of Moderate-to-Severe Ulcerative Colitis

BACKGROUND & AIMS

This American Gastroenterological Association (AGA) living guideline is intended to support practitioners in the pharmacological management of moderate-to-severe ulcerative colitis (UC).

METHODS

A multidisciplinary panel of content experts and guideline methodologists used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework to prioritize clinical questions, identify patient-centered outcomes, conduct an evidence synthesis, and develop recommendations on the pharmacological management of moderate-to-severe UC.

RESULTS

The AGA guideline panel made 14 recommendations. In adult outpatients with moderate-to-severe UC, the AGA recommends the use of infliximab, golimumab, vedolizumab, tofacitinib, upadacitinib, ustekinumab, ozanimod, etrasimod, risankizumab, and guselkumab, and suggests the use of adalimumab, filgotinib, and mirikizumab over no treatment. In patients who are naïve to advanced therapies, the AGA suggests using a higher-efficacy medication (eg, infliximab, vedolizumab, ozanimod, etrasimod, upadacitinib, risankizumab, and guselkumab) or an intermediate-efficacy medication (eg, golimumab, ustekinumab, tofacitinib, filgotinib, and mirikizumab) rather than a lower-efficacy medication (eg, adalimumab). In patients who have previously been exposed to 1 or more advanced therapies, particularly tumor necrosis factor (TNF)-α antagonists, the AGA suggests using a higher-efficacy medication (eg, tofacitinib, upadacitinib, and ustekinumab) or an intermediate-efficacy medication (eg, filgotinib, mirikizumab, risankizumab, and guselkumab) rather than a lower-efficacy medication (eg, adalimumab, vedolizumab, ozanimod, and etrasimod). In adult outpatients with moderate-to-severe UC, the AGA suggests against using thiopurine monotherapy for induction of remission, but suggests using thiopurine monotherapy over no treatment for maintenance of (typically corticosteroid-induced) remission. The AGA suggests against using methotrexate monotherapy, for induction or maintenance of remission. In adult outpatients with moderate-to-severe UC, the AGA suggests the use of infliximab, adalimumab, and golimumab in combination with an immunomodulator over corresponding monotherapy. However, the AGA makes no recommendation in favor of, or against, the use of non-TNF antagonist biologics in combination with an immunomodulator over non-TNF biologic alone. In patients with UC who are in corticosteroid-free clinical remission for at least 6 months on combination therapy of TNF antagonists and an immunomodulator, the AGA suggests against withdrawal of TNF antagonists, but makes no recommendation in favor of, or against, withdrawing immunomodulators. In adult outpatients with moderate-to-severe UC, who have failed 5-aminosalicylates, and have escalated to therapy with immunomodulators or advanced therapies, the AGA suggests stopping 5-aminosalicylates. Finally, in adult outpatients with moderate-severe UC, the AGA suggests early use of advanced therapies and/or immunomodulator therapy, rather than gradual step-up after failure of 5-aminosalicylates. The panel also proposed key implementation considerations for optimal use of these medications and identified several knowledge gaps and areas for future research.

CONCLUSIONS

This guideline provides a comprehensive, patient-centered approach to the pharmacological management of patients with moderate-to-severe UC.

Advancements in the management of pediatric inflammatory bowel disease

INTRODUCTION

The management of pediatric inflammatory bowel disease (PIBD) has drastically changed in the last decade. The limited availability of new biologics or small molecule therapies, and concerns about durability in children has necessitated the development of other advances in management to optimize care.

AREAS COVERED

This review covers guidance for management targets and advances in optimizing biologic therapies, new medical therapies, adjuvant therapies, precision medicine and mental health concerns in PIBD. This review focused on recent advances and was not intended as a complete overview of the investigations and management of pediatric IBD.

EXPERT OPINION

Advancements include standardization of treatment goals via a treat-to-target strategy, optimizing anti-TNF biologics through combination therapy or proactive drug monitoring, earlier initiation of treatment for Crohn's disease, the emergence of new biologic/advanced therapies and a growing focus on adjuvant therapies targeting the microbiome. Future progress relies on the inclusion of children/adolescents in clinical trials to facilitate faster regulatory approval for pediatric therapies and the integration of precision medicine and mental health screening to improve patient care and outcomes.

Infusion Reactions to Infliximab in Pediatric Patients with Inflammatory Bowel Disease

Infliximab (IFX) is a recombinant DNA-derived chimeric IgG monoclonal antibody protein that inhibits tumor necrosis factor alpha (TNF-α). IFX, like other agents derived from foreign proteins, can cause infusion reactions both during and after the infusion. The incidence of infusion reactions ranges between 0% and 15% in pediatric patients. The potential underlying mechanisms for these reactions may include anaphylaxis and anaphylactoid reactions, cytokine release syndrome, serum sickness-like reactions, and the development of antibodies against IFX. Several precautions can help reduce the risk of a new infusion reaction, such as a gradual increase in the infusion rate, scheduled infusions, and administering premedication or immunomodulators alongside IFX. Acute mild to moderate reactions often resolve spontaneously after a temporary cessation of the infusion or reduction in the infusion rate. Strategies like graded dose challenges and premedication can be utilized to prevent recurrence. In cases of severe reactions, desensitization or switching to an alternative biologic may be considered. This article aims to review the most recent guidelines for managing IFX-related infusion reactions in pediatric patients with inflammatory bowel disease (IBD), relying on the best available evidence.

HLA-DQA1*05 Not Associated With Ustekinumab Loss of Response and Antidrug Antibodies in Ulcerative Colitis and Crohn's Disease Patients

It is unknown if inflammatory bowel disease patients carrying the HLA-DQA1*05 allele have a greater risk of immunogenicity to ustekinumab. We observed that ustekinumab-treated patients carrying the allele did not have increased immunogenicity or reduced efficacy/serum ustekinumab concentrations vs noncarriers

Review article: Measuring disease severity in inflammatory bowel disease - Beyond treat to target

BACKGROUND

Inflammatory bowel disease (IBD) follows a heterogenous disease course and predicting a patient's prognosis is challenging. There is a wide burden of illness in IBD and existing tools measure disease activity at a snapshot in time. Comprehensive assessment of IBD severity should incorporate disease activity, prognosis, and the impacts of disease on a patient. This review investigates the concept of disease severity in adults with IBD to highlight key components contributing to this.

METHODS

To perform this narrative review, a Medline search was conducted for full-text articles available at 1st March 2024 using search terms which encompassed disease activity assessment, disease severity, prognosis, natural history of Crohn's disease (CD) and ulcerative colitis (UC), and the burden of IBD.

RESULTS

Current methods of disease assessment in IBD have evolved from a focus on the burden of symptoms to one that includes inflammatory targets, genetic, serological, and proteomic profiles, and assessments of quality-of-life (QoL), disability, and psychosocial health. Longitudinal studies of IBD suggest that the burden of illness is driven by disease phenotype, clinical markers of complicated disease course (previous intestinal resection, corticosteroid use, perianal disease in CD, recent hospitalisations in UC), gut inflammation, and the impact of IBD on the patient.

CONCLUSIONS

Disease severity in IBD can be difficult to conceptualise due to the multitude of factors that contribute to IBD outcomes. Measurement of IBD severity may better encapsulate the full burden of illness rather than gut inflammation alone at a single timepoint and may be associated with longitudinal outcomes.

Immunogenicity of monoclonal antibody: Causes, consequences, and control strategies

Antibody-based treatment was first used in 1891 for the treatment of diphtheria. Since then, monoclonal antibodies (mAbs) have been developed to treat many diseases such as cancer and act as vaccines. However, murine-derived therapeutic mAbs were found to be highly immunogenic, and caused anti-drug antibodies (ADAs) reaction, reducing their efficacy and causing severe infusion reactions. Fully human, humanised, and chimeric antibodies were then introduced for better therapeutic efficacy. With the introduction of immune response associated with mAbs immunogenicity. This review explores the immunogenicity of mAbs, its mechanism, contributing factors, and its impact on therapeutic efficacy. It also discusses immunogenicity assessment for preclinical studies and strategies for minimising immunogenicity for effective therapeutic treatment in various diseases. Finally, predicting immunogenicity in drug development is essential for selecting top drug candidates. A lot of methods can be implemented by the researchers and developers to reduce the development of ADAs while simultaneously minimising the immunogenicity reaction of mAbs.

Carriage of the HLA-DQA1⋆05 haplotype is associated with a higher risk of infratherapeutic drug concentration and higher immunogenicity in patients undergoing treatment with anti-TNF for inflammatory bowel disease

Background

The success of anti-tumor necrosis factor (TNF) drug strategies in the treatment of inflammatory bowel disease (IBD) is altered by the development of anti-drug antibodies that reduce their efficacy. Studies have shown that the HLA-DQA1⋆05 allele increases the risk of immunogenicity to anti-TNF drugs approximately twofold.

Objective

Analyze whether the presence of the HLA-DQA1⋆05 allele is associated with the development of immunogenicity and to evaluate the disease response to anti-TNF drugs (infliximab (IFX) and adalimumab (ADA)), according to the presence of this allele.

Design

This is an observational retrospective cohort study, single center, to determine the impact of HLA-DQA1⋆05 on disease activity in patients with IBD at the Hospital Universitario Virgen Macarena.

Methods

In total, 200 IBD patients were included: 109 treated with IFX and 91 with ADA. Data were collected using the computerized medical records from the DIRAYA program of the Servicio Andaluz de Salud. Response-defined as improvement-and remission-defined as the disappearance of symptoms and analytical/endoscopic signs-were assessed using activity indices (partial Mayo, Harvey-Bradshaw) in all patients. Anti-TNF drug levels were also determined, as well as the presence or absence of anti-IFX and anti-ADA antibodies. The reporting of this study conforms to the Strengthening the Reporting of Observational Studies in Epidemiology statement.

Results

The HLA-DQA1⋆05 haplotype was present in 70 (35%) patients, including 39 (36%) treated with IFX and 31 (34%) with ADA. The risk of withdrawal, intensification, as well as antibody development, was higher in patients carrying the allele and on treatment with IFX or ADA.

Conclusion

In our study, we demonstrated that there is an increased risk of immunogenicity in patients carrying the HLA-DQA1⋆05 genotype, which would support the idea of screening for this genetic variant before starting anti-TNF therapy, as its prevalence is high in the general population and increases the risk of treatment discontinuation due to loss of response.

Real-World Experience of the Association of HLADQA1*05 Allele With Loss of Response to Anti-TNF Inhibitors

Background

Antitumor necrosis factor (anti-TNF) biologics have revolutionized the treatment of inflammatory bowel disease (IBD). Previously, studies have shown an association between the HLADQA1*05 allele and the development of antibodies and were predictive of loss of response. We sought to investigate the rate of the HLADQA1*05 allele in patients with IBD at a New England center and its association with antibody development and discontinuation of anti-TNF therapy.

Methods

A single center retrospective cohort study with patients on anti-TNF inhibitor therapy being followed at our IBD clinic who had testing performed for the HLADQA1*05 allele were identified and separated into 2 different groups: HLADQA1*05 positive (HLA carriers) or HLADQA1*05 negative (HLA noncarriers). Persistence of remaining on anti-TNF therapy, measurement of drug/antibody levels, and need for dose escalation were collected and stratified amongst the 2 groups.

Results

The prevalence of the HLADQA1*05 allele among all IBD patients followed was 53%. We identified 67 IBD patients being treated with anti-TNF medications, 46 (69%) patients with Crohn's disease and 21 (31%) with ulcerative colitis. Most of the HLA carriers (85%) and HLA noncarriers (92%) remained on anti-TNF therapy at the end of the study period. Thirty-six (84%) patients had therapeutic drug monitoring performed during maintenance therapy. Three patients in the HLA carrier group had meaningful antidrug antibody levels necessitating cessation of therapy compared to one patient in the HLA noncarrier group (P = .61). Only 3 (13%) of HLA carriers and 4 (21%) of HLA noncarriers were on combination therapy with an immunomodulator. 65% of HLA carriers required dose escalation compared to 50% of HLA noncarriers (P = .70).

Conclusions

The prevalence of the HLADQA1*05 allele was 53% in our New England IBD patient population, similar to what has previously been reported in European studies. The majority of patients remained on anti-TNF therapy at the end of the study period despite carrier status. While there was a trend toward increased need for dose escalation among HLA carriers, this was not statistically significant. Future studies are needed to determine if the presence of the HLADQA1*05 allele leads to antibody development against anti-TNF inhibitors and treatment failure in patients with IBD.

Subcutaneous infliximab in Crohn's disease patients with previous immunogenic failure of intravenous infliximab

PURPOSE

Immunogenicity is a major reason for secondary loss of response to infliximab (IFX). Recent work suggested potentially lower immunogenicity of subcutaneous (SC) compared to intravenous (IV) IFX. However, it is unknown whether re-exposure to IFX SC after secondary loss of response and immunogenicity to its intravenous formulation is safe and effective.

METHODS

In a retrospective cohort study conducted at two medical centers, patients with clinically (Harvey-Bradshaw Index ≥ 5) and/or biochemically (fecal calprotectin > 250 µg/g) active Crohn's disease (CD) and previous immunogenic failure of IFX IV underwent exposure to IFX SC. Harvey-Bradshaw Index, fecal calprotectin, IFX serum concentration, and anti-drug antibodies were assessed until month 12.

RESULTS

Twenty CD patients were included. The majority of patients (90%) had previous treatment with three or more biologics. Fifteen (75%) and ten (50%) of 20 patients continued IFX SC treatment until months 6 and 12, respectively. No immediate hypersensitivity reactions were observed. Two patients discontinued IFX SC treatment because of delayed hypersensitivity at week 2 and week 4. IFX serum concentrations increased from baseline to month 12, while anti-drug antibody levels decreased. Combined clinical and biochemical remission at month 12 was observed in seven of 20 patients (35%).

CONCLUSION

Subcutaneous infliximab treatment of Crohn's disease patients with previous immunogenic failure of intravenous infliximab was well tolerated and effective in a cohort of patients with refractory Crohn's disease.

Whole Blood DNA Methylation Changes Are Associated with Anti-TNF Drug Concentration in Patients with Crohn's Disease

BACKGROUND AND AIMS

Anti-tumour necrosis factor [TNF] treatment failure in patients with inflammatory bowel disease [IBD] is common and frequently related to low drug concentrations. In order to identify patients who may benefit from dose optimisation at the outset of anti-TNF therapy, we sought to define epigenetic biomarkers in whole blood at baseline associated with anti-TNF drug concentrations at week 14.

METHODS

DNA methylation from 1104 whole blood samples from 385 patients in the Personalised Anti-TNF Therapy in Crohn's disease [PANTS] study were assessed using the Illumina EPIC Beadchip [v1.0] at baseline and weeks 14, 30, and 54. We compared DNA methylation profiles in anti-TNF-treated patients who experienced primary non-response at week 14 if they were assessed at subsequent time points and were not in remission at week 30 or 54 [infliximab n = 99, adalimumab n = 94], with patients who responded at week 14 and when assessed at subsequent time points were in remission at week 30 or 54 [infliximab n = 99, adalimumab n = 93].

RESULTS

Overall, between baseline and week 14, we observed 4999 differentially methylated positions [DMPs] annotated to 2376 genes following anti-TNF treatment. Pathway analysis identified 108 significant gene ontology terms enriched in biological processes related to immune system processes and responses. Epigenome-wide association [EWAS] analysis identified 323 DMPs annotated to 210 genes at baseline associated with higher anti-TNF drug concentrations at Week 14. Of these, 125 DMPs demonstrated shared associations with other common traits [proportion of shared CpGs compared with DMPs] including body mass index [23.2%], followed by C-reactive protein [CRP] [11.5%], smoking [7.4%], alcohol consumption per day [7.1%], and IBD type [6.8%]. EWAS of primary non-response to anti-TNF identified 20 DMPs that were associated with both anti-TNF drug concentration and primary non-response to anti-TNF with a strong correlation of the coefficients [Spearman's rho = -0.94, p <0.001].

CONCLUSION

Baseline DNA methylation profiles may be used as a predictor for anti-TNF drug concentration at week 14 to identify patients who may benefit from dose optimisation at the outset of anti-TNF therapy.

Impact of HLA-DQA1*05 Genotype in Immunogenicity and Failure to Treatment with Tumour Necrosis Factor-alpha Antagonists in Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

BACKGROUND

HLA-DQA1*05 carriage has been associated with an increased risk of immunogenicity in patients with immune-mediated inflammatory diseases treated with tumour necrosis factor-alpha [TNF-a] antagonists. Results have shown an inconsistent association with a loss of response [LOR] in patients with inflammatory bowel disease [IBD], which could be modified when using proactive optimisation and association with immunomodulatory drugs.

AIMS

To define the association of HLA-DQA1*05 on anti-drug antibody development and loss of response [LOR] to anti-TNF-a in IBD.

METHODS

We searched MEDLINE, EMBASE, and SCOPUS, for the period up to August 2023, to identify studies reporting the risk of immunogenicity and/or LOR in IBD patients with HLA-DQA1*05 genotype.

RESULTS

A total of 24 studies comprising 12 papers, 11 abstracts and one research letter, with a total of 5727 IBD patients, were included. In a meta-analysis of 10 studies [2984 patients; 41.9% with HLA-DQA1*05 genotype], HLA-DQA1*05 carriers had higher risk of immunogenicity compared with non-carriers (risk ratio, 1.54; 95% confidence interval [CI], 1.23 - 1.94; I2 = 62%) [low certainty evidence]. Lack of therapeutic drug monitoring [TDM] increased immunogenicity in the presence of risk human leukocyte antigen [HLA] [risk ratio 1.97; 95% CI, 1.35 - 2.88; I2 = 66%], whereas proactive TDM revoked this association [very low certainty of evidence]. A meta-analysis of six studies [765 patients] found that risk for secondary LOR was higher among HLA-DQA1*05 carriers [hazard ratio 2.21; 95% CI, 1.69 - 2.88; I2 = 0%] [very low certainty evidence], although definition and time to assessment varied widely among studies.

CONCLUSION

HLA-DQA1*05 carriage may be associated with an increased risk of immunogenicity and secondary LOR in IBD patients treated with TNF-a antagonists.

The Contribution of Genetic and Epigenetic Factors: An Emerging Concept in the Assessment and Prognosis of Inflammatory Bowel Diseases

Inflammatory bowel disease (IBD) represents heterogeneous and relapsing intestinal conditions with a severe impact on the quality of life of individuals and a continuously increasing prevalence. In recent years, the development of sequencing technology has provided new means of exploring the complex pathogenesis of IBD. An ideal solution is represented by the approach of precision medicine that investigates multiple cellular and molecular interactions, which are tools that perform a holistic, systematic, and impartial analysis of the genomic, transcriptomic, proteomic, metabolomic, and microbiomics sets. Hence, it has led to the orientation of current research towards the identification of new biomarkers that could be successfully used in the management of IBD patients. Multi-omics explores the dimension of variation in the characteristics of these diseases, offering the advantage of understanding the cellular and molecular mechanisms that affect intestinal homeostasis for a much better prediction of disease development and choice of treatment. This review focuses on the progress made in the field of prognostic and predictive biomarkers, highlighting the limitations, challenges, and also the opportunities associated with the application of genomics and epigenomics technologies in clinical practice.

Implementation of pharmacogenomics: Where are we now?

Pharmacogenomics (PGx), examining the effect of genetic variation on interpatient variation in drug disposition and response, has been widely studied for several decades. However, as cost, as well as turnaround time associated with PGx testing, has significantly improved, the use of PGx in the clinical setting has been gaining momentum. Nevertheless, challenges have emerged in the broader clinical implementation of PGx. In this review, we will outline current models of PGx delivery and methodologies of evaluation, and discuss clinically relevant PGx tests and associated medications. Additionally, we will describe our approach for the broad implementation of pre-emptive DPYD genotyping in patients taking fluoropyrimidines in Ontario, Canada, as an example of clinically actionable PGx testing with sufficient clinical evidence of patient benefit that can become a new standard of patient care. We will highlight challenges associated with PGx testing, including a lack of diversity in PGx studies as well as general limitations that impact the broad adoption of PGx testing. Lastly, we examine the future of PGx, discussing new clinical targets, methodologies and analysis approaches.

Personalised therapy in inflammatory bowel disease

Inflammatory bowel diseases (IBD), with ulcerative colitis and Crohn's disease being their most common presentations, comprise a spectrum of diverse disease phenotypes, exhibiting variable behaviors ranging from an indolent course to aggressive phenotypes that impact quality of life of these patients. The last two decades have been marked by the development of new medications (biological therapy and novel small molecules) with diverse mechanisms of action, which have revolutionized the management of IBD, thereby enhancing the quality of life for these patients. This landscape of multiple therapeutic options underscores the need to define which medication will benefit each patient the most and at what speed it should be started. The objective of this review is to present personalized approaches for patients with IBD, thus contributing to therapeutic management.

HLA-DQA1*05 correlates with increased risk of anti-drug antibody development and reduced response to infliximab in Chinese patients with Crohn's disease

Background

The efficacy of anti-TNF therapy in Crohn's disease (CD), such as infliximab, is often compromised by the development of anti-drug antibodies (ADAs). The genetic variation HLA-DQA1*05 has been linked to the immunogenicity of biologics, influencing ADA formation. This study investigates the correlation between HLA-DQA1*05 and ADA formation in CD patients treated with infliximab in a Chinese Han population and assesses clinical outcomes.

Methods

In this retrospective cohort study, 345 infliximab-exposed CD patients were genotyped for HLADQ A1*05A > G (rs2097432). We evaluated the risk of ADA development, loss of infliximab response, adverse events, and treatment discontinuation among variant and wild-type allele individuals.

Results

A higher percentage of patients with ADAs formation was observed in HLA-DQA1*05 G variant carriers compared with HLA-DQA1*05 wild-type carriers (58.5% vs 42.9%, P = 0.004). HLA-DQA1*05 carriage significantly increased the risk of ADAs development (adjusted hazard ratio = 1.65, 95% CI 1.18-2.30, P = 0.003) and was associated with a greater likelihood of infliximab response loss (adjusted HR = 2.55, 95% CI 1.78-3.68, P < 0.0001) and treatment discontinuation (adjusted HR = 2.21, 95% CI 1.59-3.06, P < 0.0001). Interestingly, combined therapy with immunomodulators increased the risk of response loss in HLA-DQA1*05 variant carriers.

Conclusions

HLA-DQA1*05 significantly predicts ADAs formation and impacts treatment outcomes in infliximab-treated CD patients. Pre-treatment screening for this genetic factor could therefore be instrumental in personalizing anti-TNF therapy strategies for these patients.

Biomarkers for Personalizing IBD Therapy: The Quest Continues

Despite recent advances in the understanding of the pathogenesis of inflammatory bowel diseases (IBD) and advent of multiple targeted therapies, approximately one-third of patients are primary non-responders to initiated treatment, and half of patients lose response over time. There is currently a lack of available biomarkers that would prognosticate therapeutic effectiveness of these advanced therapies. This is partly explained by insufficient characterization of the functional roles assumed by the chosen molecular targets during disease treatment. There is a dire need for validated objective biomarkers, which could be indicators of a biological process, that can be applied in clinical practice to assist us in assigning therapies to patients with the highest probability of response. An appropriate molecular and cellular characterization that accounts for the interindividual differences in drug efficacy and potential side effects would help to guide clinicians in the management of patients with IBD and represent a major step to tailor a more personalized approach to treatment. An appropriate combination of complementing biomarkers should ideally incorporate a multimodal analysis in which genetic, microbial, transcriptional, proteomic, metabolic, and immunologic data are combined to enable a truly personalized approach. This would classify patients into disease subgroups according to molecular characteristics, which would enable us to initiate the most appropriate therapeutic substance. Emergence of single-cell technologies to map the intestinal cellular landscape and multiomic approaches have helped to further dissect the pathogenic mechanisms of mucosal inflammation, but the clinical translation of potential biomarkers remains cumbersome, and an ongoing concerted effort by the IBD community is required.

Intestinal mRNA expression profiles associated with mucosal healing in ustekinumab-treated Crohn's disease patients: bioinformatics analysis and prospective cohort validation

BACKGROUND

Variations exist in the response of patients with Crohn's disease (CD) to ustekinumab (UST) treatment, but the underlying cause remains unknown. Our objective was to investigate the involvement of immune cells and identify potential biomarkers that could predict the response to interleukin (IL) 12/23 inhibitors in patients with CD.

METHODS

The GSE207022 dataset, which consisted of 54 non-responders and 9 responders to UST in a CD cohort, was analyzed. Differentially expressed genes (DEGs) were identified and subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Least absolute shrinkage and selection operator (LASSO) regression was used to screen the most powerful hub genes. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the predictive performances of these genes. Single-sample Gene Set Enrichment Analysis (ssGSEA) was used to estimate the proportions of immune cell types. These significantly altered genes were subjected to cluster analysis into immune cell-related infiltration. To validate the reliability of the candidates, patients prescribed UST as a first-line biologic in a prospective cohort were included as an independent validation dataset.

RESULTS

A total of 99 DEGs were identified in the integrated dataset. GO and KEGG analyses revealed significant enrichment of immune response pathways in patients with CD. Thirteen genes (SOCS3, CD55, KDM5D, IGFBP5, LCN2, SLC15A1, XPNPEP2, HLA-DQA2, HMGCS2, DDX3Y, ITGB2, CDKN2B and HLA-DQA1), which were primarily associated with the response versus nonresponse patients, were identified and included in the LASSO analysis. These genes accurately predicted treatment response, with an area under the curve (AUC) of 0.938. T helper cell type 1 (Th1) cell polarization was comparatively strong in nonresponse individuals. Positive connections were observed between Th1 cells and the LCN2 and KDM5D genes. Furthermore, we employed an independent validation dataset and early experimental verification to validate the LCN2 and KDM5D genes as effective predictive markers.

CONCLUSIONS

Th1 cell polarization is an important cause of nonresponse to UST therapy in patients with CD. LCN2 and KDM5D can be used as predictive markers to effectively identify nonresponse patients.

TRIAL REGISTRATION

Trial registration number: NCT05542459; Date of registration: 2022-09-14; URL: https://www.

CLINICALTRIALS

gov .

HLA-DQA1*05 Was Not Associated With Primary Nonresponse or Loss of Response to First Anti-TNF in Real-World Inflammatory Bowel Disease Patients

BACKGROUND

We lack predictors of response to biologics in the management of patients with inflammatory bowel disease (IBD). A recent study has shown a significant association between HLA-DQA1*05 carriers and the development of loss of response to anti-tumor necrosis factor (TNF) mediated by immunogenicity.

METHODS

Retrospective single-center cohort study including IBD patients who had received anti-TNF therapy as a first biologic and whose HLA-DQA1*05 had been determined. Primary nonresponse and secondary failure (assessed by survival analysis) have been evaluated as well as safety outcomes.

RESULTS

A total of 199 IBD patients (161 [81%] with Crohn's disease and 38 [19%] with ulcerative colitis) were included. A total of 42.4% were HLA-DQA1*05 carriers and 60% received combination therapy at the start of anti-TNF treatment. Median follow-up was 24 (interquartile range, 11-66) months. No statistically significant differences were found in primary nonresponse to anti-TNF (89.3% vs 87.8%; P = .825), depending on HLA carriers and noncarriers. No differences in secondary loss of response according to HLA variant in any of the analyses performed (full cohort, according to IBD or anti-TNF type) were observed. Again, no differences were observed in patients treated with combination therapy. In terms of safety, no significant differences were found in the rate of infusion reactions or serious adverse events.

CONCLUSION

In our real-life cohort of IBD patients treated for the first time with anti-TNF, being an HLA-DQA1*05 carrier did not act as a predictor of response failure, either primary or secondary. The safety of anti-TNF treatment has also not been influenced by the variant.

How close are we to a success stratification tool for improving biological therapy in ulcerative colitis?

INTRODUCTION

Biological therapies have become the standard treatment for ulcerative colitis (UC). However, clinical remission rates post-induction therapy remain modest at 40-50%, with many initial responders losing response over time. Current treatment strategies frequently rely on a 'trial and error' approach, leading to prolonged periods of ineffective and costly therapies for patients, accompanied by associated treatment complications.

AREA COVERED

This review discusses current evidence on risk stratification tools for predicting therapeutic efficacy and minimizing adverse events in UC management. Recent studies have identified predictive factors for biologic therapy response. In the context of personalized medicine, the goal is to identify patients at high risk of progression and complications, as well as those likely to respond to specific therapies. Essential risk stratification tools include clinical decision-making aids, biomarkers, genomics, multi-omics factors, endoscopic, imaging, and histological assessments.

EXPERT OPINION

Employing risk stratification tools to predict therapeutic response and prevent treatment-related complications is essential for precision medicine in the biological management of UC. These tools are necessary to select the most suitable treatment for each individual patient, thereby enhancing efficacy and safety.

Best Practice for Therapeutic Drug Monitoring of Infliximab: Position Statement from the International Association of Therapeutic Drug Monitoring and Clinical Toxicology

BACKGROUND

Infliximab, an anti-tumor necrosis factor monoclonal antibody, has revolutionized the pharmacological management of immune-mediated inflammatory diseases (IMIDs). This position statement critically reviews and examines existing data on therapeutic drug monitoring (TDM) of infliximab in patients with IMIDs. It provides a practical guide on implementing TDM in current clinical practices and outlines priority areas for future research.

METHODS

The endorsing TDM of Biologics and Pharmacometrics Committees of the International Association of TDM and Clinical Toxicology collaborated to create this position statement.

RESULTS

Accumulating data support the evidence for TDM of infliximab in the treatment of inflammatory bowel diseases, with limited investigation in other IMIDs. A universal approach to TDM may not fully realize the benefits of improving therapeutic outcomes. Patients at risk for increased infliximab clearance, particularly with a proactive strategy, stand to gain the most from TDM. Personalized exposure targets based on therapeutic goals, patient phenotype, and infliximab administration route are recommended. Rapid assays and home sampling strategies offer flexibility for point-of-care TDM. Ongoing studies on model-informed precision dosing in inflammatory bowel disease will help assess the additional value of precision dosing software tools. Patient education and empowerment, and electronic health record-integrated TDM solutions will facilitate routine TDM implementation. Although optimization of therapeutic effectiveness is a primary focus, the cost-reducing potential of TDM also merits consideration.

CONCLUSIONS

Successful implementation of TDM for infliximab necessitates interdisciplinary collaboration among clinicians, hospital pharmacists, and (quantitative) clinical pharmacologists to ensure an efficient research trajectory.

Mechanisms and management of loss of response to anti-TNF therapy for patients with Crohn's disease: 3-year data from the prospective, multicentre PANTS cohort study

BACKGROUND

We sought to report the effectiveness of infliximab and adalimumab over the first 3 years of treatment and to define the factors that predict anti-TNF treatment failure and the strategies that prevent or mitigate loss of response.

METHODS

Personalised Anti-TNF therapy in Crohn's disease (PANTS) is a UK-wide, multicentre, prospective observational cohort study reporting the rates of effectiveness of infliximab and adalimumab in anti-TNF-naive patients with active luminal Crohn's disease aged 6 years and older. At the end of the first year, sites were invited to enrol participants still receiving study drug into the 2-year PANTS-extension study. We estimated rates of remission across the whole cohort at the end of years 1, 2, and 3 of the study using a modified survival technique with permutation testing. Multivariable regression and survival analyses were used to identify factors associated with loss of response in patients who had initially responded to anti-TNF therapy and with immunogenicity. Loss of response was defined in patients who initially responded to anti-TNF therapy at the end of induction and who subsequently developed symptomatic activity that warranted an escalation of steroid, immunomodulatory, or anti-TNF therapy, resectional surgery, or exit from study due to treatment failure. This study was registered with ClinicalTrials.gov, NCT03088449, and is now complete.

FINDINGS

Between March 19, 2014, and Sept 21, 2017, 389 (41%) of 955 patients treated with infliximab and 209 (32%) of 655 treated with adalimumab in the PANTS study entered the PANTS-extension study (median age 32·5 years [IQR 22·1-46·8], 307 [51%] of 598 were female, and 291 [49%] were male). The estimated proportion of patients in remission at the end of years 1, 2, and 3 were, for infliximab 40·2% (95% CI 36·7-43·7), 34·4% (29·9-39·0), and 34·7% (29·8-39·5), and for adalimumab 35·9% (95% CI 31·2-40·5), 32·9% (26·8-39·2), and 28·9% (21·9-36·3), respectively. Optimal drug concentrations at week 14 to predict remission at any later timepoints were 6·1-10·0 mg/L for infliximab and 10·1-12·0 mg/L for adalimumab. After excluding patients who had primary non-response, the estimated proportions of patients who had loss of response by years 1, 2, and 3 were, for infliximab 34·4% (95% CI 30·4-38·2), 54·5% (49·4-59·0), and 60·0% (54·1-65·2), and for adalimumab 32·1% (26·7-37·1), 47·2% (40·2-53·4), and 68·4% (50·9-79·7), respectively. In multivariable analysis, loss of response at year 2 and 3 for patients treated with infliximab and adalimumab was predicted by low anti-TNF drug concentrations at week 14 (infliximab: hazard ratio [HR] for each ten-fold increase in drug concentration 0·45 [95% CI 0·30-0·67], adalimumab: 0·39 [0·22-0·70]). For patients treated with infliximab, loss of response was also associated with female sex (vs male sex; HR 1·47 [95% CI 1·11-1·95]), obesity (vs not obese 1·62 [1·08-2·42]), baseline white cell count (1·06 [1·02-1·11) per 1 × 109 increase in cells per L), and thiopurine dose quartile. Among patients treated with adalimumab, carriage of the HLA-DQA1*05 risk variant was associated with loss of response (HR 1·95 [95% CI 1·17-3·25]). By the end of year 3, the estimated proportion of patients who developed anti-drug antibodies associated with undetectable drug concentrations was 44·0% (95% CI 38·1-49·4) among patients treated with infliximab and 20·3% (13·8-26·2) among those treated with adalimumab. The development of anti-drug antibodies associated with undetectable drug concentrations was significantly associated with treatment without concomitant immunomodulator use for both groups (HR for immunomodulator use: infliximab 0·40 [95% CI 0·31-0·52], adalimumab 0·42 [95% CI 0·24-0·75]), and with carriage of HLA-DQA1*05 risk variant for infliximab (HR for carriage of risk variant: infliximab 1·46 [1·13-1·88]) but not for adalimumab (HR 1·60 [0·92-2·77]). Concomitant use of an immunomodulator before or on the day of starting infliximab was associated with increased time without the development of anti-drug antibodies associated with undetectable drug concentrations compared with use of infliximab alone (HR 2·87 [95% CI 2·20-3·74]) or introduction of an immunomodulator after anti-TNF initiation (1·70 [1·11-2·59]). In years 2 and 3, 16 (4%) of 389 patients treated with infliximab and 11 (5%) of 209 treated with adalimumab had adverse events leading to treatment withdrawal. Nine (2%) patients treated with infliximab and two (1%) of those treated with adalimumab had serious infections in years 2 and 3.

INTERPRETATION

Only around a third of patients with active luminal Crohn's disease treated with an anti-TNF drug were in remission at the end of 3 years of treatment. Low drug concentrations at the end of the induction period predict loss of response by year 3 of treatment, suggesting higher drug concentrations during the first year of treatment, particularly during induction, might lead to better long-term outcomes. Anti-drug antibodies associated with undetectable drug concentrations of infliximab, but not adalimumab, can be predicted by carriage of HLA-DQA1*05 and mitigated by concomitant immunomodulator use for both drugs.

FUNDING

Guts UK, Crohn's and Colitis UK, Cure Crohn's Colitis, AbbVie, Merck Sharp and Dohme, Napp Pharmaceuticals, Pfizer, and Celltrion Healthcare.