Shomron Ben-Horin

Second European evidence-based consensus on the prevention, diagnosis and management of opportunistic infections in inflammatory bowel disease

The treatment of inflammatory bowel disease (IBD) has been revolutionised over the past decade by the increasing use of immunomodulators, mainly azathioprine (AZA)/6-mercaptopurine (6-MP) and methotrexate (MTX), together with the advent of biological therapy. Immunomodulators are being used more often and earlier in the course of the disease.1 The introduction of biologic agents, especially inhibitors of the key proinflammatory cytokine, tumor necrosis factor alpha (TNF-α) initiated a new therapeutic era, whose use has grown continuously since their introduction in 1998.2 With such immunomodulation, the potential for opportunistic infection is a key safety concern for patients with IBD. Opportunistic infections pose particular problems for the clinician: they are often difficult to recognise and are associated with appreciable morbidity or mortality, because they are potentially serious and hard to treat effectively. Enhancing awareness and improving the knowledge of gastroenterologists about opportunistic infections are important elements to optimise patient outcomes through the development of preventive or early diagnostic strategies. A long list of opportunistic infections has been described in patients with IBD. Many questions remain unanswered, not only concerning the need for screening, preventive measures or the best diagnostic approach, but also on appropriate treatment and management of immunomodulator therapy once infection occurs. This led the European Crohns and Colitis Organisation (ECCO) to establish a Consensus meeting on opportunistic infections in IBD. The formal process of a Consensus meeting has been described,3 but the purpose is to quantify expert opinion in the context of a systematic review of existing evidence. To organise the work, infections were classified into six major topics (see plan). Specific questions were asked for each infectious agent. The different topics were distributed to working groups that comprised junior and senior gastroenterologists with infectious disease experts. Each group performed a systematic review of the literature and answered …

Review article: loss of response to anti-TNF treatments in Crohn's disease.

Aliment Pharmacol Ther 2011; 33: 987–995

Report of the ECCO pathogenesis workshop on anti-TNF therapy failures in inflammatory bowel diseases: Definitions, frequency and pharmacological aspects

The first ECCO pathogenesis workshop focused on anti-TNF therapy failures in inflammatory bowel diseases (IBDs). The overall objective was to better understand and explore primary non response and loss of response to anti-TNF agents in IBD. The outcome of this workshop is presented into two parts. This first section addresses definitions, frequency and pharmacological aspects of anti-TNF therapy failure, including pharmacokinetics of anti-TNF monoclonal antibodies and immune and non-immune mediated clearance of anti-TNF mAbs. The second section concerns the biological roles of TNF and TNF antagonists, including mechanisms of action of anti-TNF agents, and discuss hypothesis regarding their failures and phenomenon of paradoxical inflammation, including the potential role of TNF independent inflammatory pathways.

The temporal evolution of antidrug antibodies in patients with inflammatory bowel disease treated with infliximab

Objective To characterise the temporal evolution of antibodies to infliximab (ATI). Design Prospective observational study of infliximab-treated patients with inflammatory bowel disease between 2009 and 2012. Interventions Trough levels of infliximab and ATI were measured before each infusion by anti-λ ELISA. Patients were monitored for disease activity by clinical activity indexes and for dose-intensification or infliximab cessation. The occurrence of transient ATI disappearing spontaneously without intervention was recorded separately. Results 125 patients were included (98 Crohns disease, 27 ulcerative colitis, median follow-up 11.5±22 months) and 1119 sera were analysed for infliximab and ATI levels. Kaplan-Meier analysis showed that 42% of patients remained ATI-free by 4 years of treatment. Most (90%) of the patients who developed ATI did so within the first 12 months of therapy, whereas transient ATI were detected throughout the duration of infliximab therapy (p<0.001). ATI incidence was similar between patients who received infliximab previously (episodic/interrupted therapy patients, n=14) and scheduled-therapy patients (n=111). In the scheduled group, combination immunomodulator+infliximab resulted in longer ATI-free survival compared with monotherapy (p=0.003, logrank test). Survival free of clinical loss of response was enjoyed by 51% of patients, and serial measurements showed that ATI development often preceded the onset of clinical flare. Conclusions When followed prospectively, most patients who develop ATI do so within the first 12 months of therapy. This incidence is reduced by concomitant immunomodulator even in scheduled-therapy patients. In contrast, transient ATI, which are of little clinical significance, can appear haphazardly at any time during treatment. The onset of clinical loss of response may lag behind the appearance of anti-infliximab antibodies.

The immunogenic part of infliximab is the F(ab′)2, but measuring antibodies to the intact infliximab molecule is more clinically useful

Objectives To localise the immunogenic part of infliximab and evaluate the clinical usefulness of measuring antibodies against infliximab fragments. Design Observational study. Settings A specialised inflammatory bowel disease (IBD) centre in a tertiary hospital. Interventions Serum was collected from patients with IBD and controls. Antibodies against whole infliximab (ATI) and against the digested Fc, F(ab′)2 and F(ab′) fragments were measured by a specifically developed ELISA and by western blotting. A separate ELISA was used to determine infliximab levels in serum. Results 109 serum samples from 62 infliximab-treated patients were tested along with 64 control samples. Anti-F(ab′)2 antibodies were found in 28/42 (67%) samples with positive ATI, all from infliximab-exposed patients. Anti-F(ab′)2 antibodies were also present in 26 of the remaining 67 (39%) samples from exposed patients despite absent ATI. No specific anti-Fc antibodies were detected. Low trough infliximab level and high ATI level was found in 10/12 patients (83%) with complete loss of response to infliximab, but in only 5/14 patients (36%, p=0.02) who regained response to intensified infliximab regimen and in 2/24 patients (8%, p<0.001) in maintained remission while on 5 mg/kg/8 week infliximab treatment. Although Anti-F(ab′)2 antibodies showed similar test characteristics to ATI in patients losing response to infliximab, they were also detected in 61% of patients in maintained remission, thereby limiting their clinical usefulness. No cross reactivity to adalimumab was noted. Conclusions F(ab′)2 is the immunogenic fragment of infliximab. However, ATI level in serum—combined with measurement of trough infliximab level—is better correlated with the clinical response to infliximab or with its loss.

Optimizing anti-TNF treatments in inflammatory bowel disease.

BACKGROUND Failure of anti-TNF treatment in inflammatory bowel disease (IBD) patients can take on several forms, each posing distinct etio-pathogenic considerations and management dilemmas. AIM The aim of this study is to review the mechanisms responsible for the various forms of anti-TNF failures in IBD and to elucidate strategies for optimizing clinical efficacy. RESULTS Primary failures of anti-TNF induction therapy occur in up to 40% of patients in clinical trials and in 10-20% in clinical series. Longer disease duration, smoking and several genetic mutations are predisposing factors for primary failures. Curiously, primary non-response is probably not a class-effect phenomenon since switching to another anti-TNF is effective in over 50% of such patients. Secondary loss of response is also a common clinical problem with incidence ranging between 23 and 46% at 12months after anti-TNF initiation. Underlying mechanisms are often related to increased anti-TNF clearance by anti-drug antibodies, but may also include other causes for recalcitrant IBD activity as well as disorders that are unrelated to IBD itself. Astute management begins with verifying the presence of uncontrolled inflammatory IBD activity as a cause for patients symptoms. Next, it is prudent to consider a trial of wait-and-see approach, since in some patients with mild-moderate symptoms, loss of response may resolve without alteration of therapy. If it does not, measuring anti-TNF trough levels and anti-drug antibodies may clarify the underlying mechanism in individual patients although there are still limited and conflicting data regarding the role of these measurements in guiding the choice between dose-intensification, switch to another anti-TNF or to another immuno-modulator, and the addition of an immuno-modulator as a combination therapy with the failing anti-TNF. Anti-TNF re-induction after prior drug-holiday is a distinct clinical scenario and scarce evidence suggests re-induction outcome to be dependent on the circumstances when drug-holiday was commenced. Finally, discontinuation of anti-TNF in patients with stable deep clinico-biologic and mucosal remission may be a viable option, as in these carefully selected patients the majority may enjoy long-term remission without the need for continued anti-TNF treatment.

TNF Activates a NF-κB–Regulated Cellular Program in Human CD45RA– Regulatory T Cells that Modulates Their Suppressive Function

Emerging data suggest that regulatory T cell (Treg) dysfunction and consequent breakdown of immunological self-tolerance in autoimmunity can be mediated by factors that are not Treg-intrinsic (e.g., cytokines). Indeed, recent studies show that in rheumatoid arthritis the proinflammatory cytokine TNF reduces the suppressive function of Tregs, whereas in vivo TNF blockade restores this function and accordingly self-tolerance. However, until now a coherent mechanism by which TNF regulates the Treg has not been described. In this paper, we show that TNF induces preferential and significant activation of the canonical NF-κB pathway in human Tregs as compared with CD25– conventional T cells. Furthermore, TNF induced primarily in CD45RA– Tregs a transcription program highly enriched for typical NF-κB target genes, such as the cytokines lymphotoxin-α and TNF, the TNFR superfamily members FAS, 4-1BB, and OX-40, various antiapoptotic genes, and other important immune-response genes. FACS analysis revealed that TNF also induced upregulation of cell surface expression of 4-1BB and OX40 specifically in CD45RA–FOXP3+ Tregs. In contrast, TNF had only a minimal effect on the Treg’s core transcriptional signature or on the intracellular levels of the FOXP3 protein in Tregs. Importantly, TNF treatment modulated the capacity of Tregs to suppress the proliferation and IFN-γ secretion by conventional T cells, an effect that was fully reversed by cotreatment with anti-TNFR2 mAbs. Our findings thus provide new mechanistic insight into the role of TNF and TNFR2 in the pathogenesis of autoimmunity.

Adalimumab drug and antibody levels as predictors of clinical and laboratory response in patients with Crohn's disease

Adalimumab is an effective treatment for Crohns disease (CD). Anti‐adalimumab antibodies (AAA) and low trough serum drug concentrations have been implicated as pre‐disposing factors for treatment failure.

Doubling the infliximab dose versus halving the infusion intervals in Crohn's disease patients with loss of response

Background: Intensifying infliximab therapy is often practiced in Crohns disease (CD) patients losing response to the drug but there are no data if halving the interval is superior to doubling the dose. We aimed to assess the efficacy of infliximab dose intensification by interval‐halving compared with dose‐doubling. Methods: A multicenter retrospective study of CD patients losing response to infliximab was undertaken. The clinical outcome of patients whose infusion intervals were halved (5 mg/kg/4 weeks) was compared with patients treated by dose‐doubling (10 mg/kg/8 weeks). Results: In all, 168 patients were included from 18 centers in Europe, USA, and Israel. Of these, 112 were intensified by dose‐doubling and 56 received interval‐halving strategy. Early response to dose‐escalation was experienced by 86/112 (77%) patients in the dose‐doubling group compared with 37/56 patients (66%) in the interval‐halving group (odds ratio [OR] 1.7, 95% confidence interval [CI] 0.8–3.4, P = 0.14). Sustained clinical response at 12 months postescalation was maintained in 50% of patients in the dose‐doubling group compared with 39% in the interval‐halving group (OR 1.5, 95% CI 0.8–2.9, P = 0.2). On multivariate analysis, predictors of long‐term response to escalation were a nonsmoking status, CD diagnosis between 16–40 years of age, and normal C‐reactive protein (CRP). Conclusions: Dose intensification leads to a sustained regained response in 47% of CD patients who lost response to standard infliximab dose, but halving the infusion intervals is probably not superior to dose‐doubling. Given the costs and patient inconvenience incurred by an additional infusion visit, the dose‐doubling strategy may be preferable to the interval‐halving strategy. (Inflamm Bowel Dis 2012;)

Anti-tumor necrosis factor and postoperative complications in Crohn's disease: systematic review and meta-analysis.

Background: Anti‐tumor necrosis factor (TNF) antibodies are efficacious in patients with Crohns disease (CD) but the influence of these medications on surgical outcomes in CD patients has been frequently debated. The aim was to evaluate the impact of preoperative treatment with anti‐TNF antibodies on postoperative complications in CD patients undergoing abdominal surgery. Methods: A systematic review and meta‐analysis of comparative cohort studies was performed assessing postoperative complication rates in CD patients who were treated with anti‐TNF antibodies within 3 months before surgery versus patients who were not. The primary outcome was overall complication rate within 1 month of surgery. Secondary outcomes included the rate of infectious and noninfectious complications. The quality of studies was assessed based on selection of patients and controls, comparability of the study groups, and assessment of outcomes. Odds ratios (OR) with 95% confidence intervals (CIs) were computed. Results: A total of eight studies including 1641 patients were included in our meta‐analysis. Preoperative infliximab therapy in CD patients undergoing abdominal surgery was associated with a trend toward an increased rate of total complications (OR 1.72, 95% CI, 0.93–3.19). Anti‐TNF treatments were associated with a modestly increased risk of infectious complications (OR 1.50, 95% CI 1.08–2.08), mostly remote from the surgical site (OR 2.07 95% CI 1.30–3.30) and with a trend toward a higher rate of noninfectious complications (OR 2.00, 95% CI 0.89–4.46). Conclusion: Preoperative infliximab treatment is associated with an increased risk of postoperative infectious complications, mostly nonlocal. A trend toward an increased risk of noninfectious and overall complications was also observed. (Inflamm Bowel Dis 2012;)