Comprehensive review: antitumor necrosis factor agents in inflammatory bowel disease and factors implicated in treatment response

Inflammatory Bowel Disease: An Overview of Immune Mechanisms and Biological Treatments

Inflammatory bowel diseases (IBD) are characterized by chronic inflammation of the intestinal tract associated with an imbalance of the intestinal microbiota. Crohn's disease (CD) and ulcerative colitis (UC) are the most widely known types of IBD and have been the focus of attention due to their increasing incidence. Recent studies have pointed out genes associated with IBD susceptibility that, together with environment factors, may contribute to the outcome of the disease. In ulcerative colitis, there are several therapies available, depending on the stage of the disease. Aminosalicylates, corticosteroids, and cyclosporine are used to treat mild, moderate, and severe disease, respectively. In Crohn's disease, drug choices are dependent on both location and behavior of the disease. Nowadays, advances in treatments for IBD have included biological therapies, based mainly on monoclonal antibodies or fusion proteins, such as anti-TNF drugs. Notwithstanding the high cost involved, these biological therapies show a high index of remission, enabling a significant reduction in cases of surgery and hospitalization. Furthermore, migration inhibitors and new cytokine blockers are also a promising alternative for treating patients with IBD. In this review, an analysis of literature data on biological treatments for IBD is approached, with the main focus on therapies based on emerging recombinant biomolecules.

Recombinant human MFG-E8 ameliorates colon damage in DSS- and TNBS-induced colitis in mice

Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the digestive system and typically requires lifelong medical care. Recombinant human MFG-E8 (rhMFG-E8) is a 364-amino acid protein, which promotes apoptotic cell clearance and reduces inflammation. This study investigates the therapeutic effect of rhMFG-E8 on two well-established mouse models of IBD. Acute mucosal injury leading to colitis was caused by exposing C57BL/6 mice to 4% dextran sodium sulfate (DSS) in the drinking water over 7 days, and BALB/c mice to a single intrarectal dose of 2.75 mg of 2,4,6-trinitrobenzene sulfonic acid (TNBS). Upon clinical onset of colitis (day 2 in the DSS model and day 1 in the TNBS model), mice were treated with daily subcutaneous injections of rhMFG-E8 (60 or 120 μg/kg/day) or vehicle (saline) for 6 days. Treatment with rhMFG-E8 significantly attenuated colitis in both models in a dose-dependent way. Treatment of DSS-induced colitis with rhMFG-E8 (120 μg/kg/day) decreased weight loss by 59%, the colitis severity score by 71%, and colon shrinkage by 49% when compared with vehicle. Similarly, treatment of TNBS-induced colitis with rhMFG-E8 (120 μg/kg/day) decreased weight loss by 97%, the colitis severity score by 82%, and colon shrinkage by 62% when compared with vehicle. In both models, the colons of animals receiving rhMFG-E8 showed marked reduction in neutrophil infiltration, cytokine and chemokine expression, and apoptotic cell counts. In conclusion, rhMFG-E8 ameliorates DSS- and TNBS-induced colitis, suggesting that it has the potential to become a novel therapeutic agent for IBD.

Anti-TNF levels and anti-drug antibodies, immunosuppressants and clinical outcomes in inflammatory bowel disease

The anti-tumor necrosis factor-α (TNF) antibodies have revolutionized the management of ulcerative colitis and Crohn's disease. The development of assays to allow for the measurements of serum drug levels and anti-drug antibodies have provided a more objective means of therapeutic decision making, particularly among patients losing response to treatment. Additionally, more evidence is emerging that indicates the relationship between drug levels and response to therapy including clinical response, mucosal healing and sustained remission. The use of combination therapies of the anti-TNF agents and the thiopurine immunosuppressants may also decrease immunogenicity to the anti-TNF agents and potentiate response to therapy. With more evidence emerging evidence of the importance of therapeutic drug levels and anti-drug antibodies, clinicians may be able to better optimize the current arsenal of inflammatory bowel disease therapeutics to achieve greater rates of durable remission and improved quality of life.

Tumor necrosis factor inhibitors: clinical utility in autoimmune diseases

Tumor necrosis factor (TNF) production is amplified in several autoimmune disorders. In the 1990s, it became a validated therapeutic target used for the treatment of conditions such as rheumatoid arthritis and inflammatory bowel disease. Biologic drugs targeting TNF include engineered monoclonal antibodies and fusion proteins. Currently, there are 5 Food and Drug Administration-approved TNF inhibitors (infliximab, etanercept, adalimumab, certolizumab, and golimumab), representing close to $20 billion in sales. Clinical trials remain open to test their efficacy and safety compared with one another, as well as to measure clinical outcomes in different conditions and patient populations. The industry is also eager to develop biotherapeutics that are similar but cheaper than the currently existing biologics or are safer with higher efficacy; these are the so-called "biosimilars." Clinical utility of TNF inhibitors and indications of mono- or combined therapy with immunomodulators are reviewed here. Pharmacokinetics of the TNF inhibitors is affected by routes of administration, clearance mechanisms of immunoglobulins, and immunogenicity. Finally, strategies for management of treatment efficacy and increasing evidence for monitoring of serum concentration of TNF inhibitors are discussed, assessing for the presence of the antidrug antibodies and the different analytical methods available for laboratory testing. As clinical applications of the TNF inhibitors expand, and other classes join the revolution in the treatment of chronic inflammatory disorders, therapeutic drug monitoring of biologics will become increasingly important, with the potential to dramatically improve patient care and management.

Effectiveness and safety of infliximab in two cases of severe chondrocalcinosis: nine years of follow-up

Objectives. To investigate the efficacy of infliximab in the treatment of severe calcium pyrophosphate deposition diseases (CPPD). Methods. Two patients with severe CPPD and diffuse idiopathic skeletal hyperostosis- (DISH-) like phenotype are described. Both patients were resistant to therapy with nonsteroidal anti-inflammatory drugs (NSAIDs). Both patients were treated with infliximab, a TNF-α receptor antagonist, for nine years. Results. Treatment with infliximab resulted in major clinical and laboratory improvements without relevant side effects. Conclusions. These results suggest that infliximab may be an effective treatment of severe CPDD.

Patient factors that increase infliximab clearance and shorten half-life in inflammatory bowel disease: a population pharmacokinetic study

BACKGROUND

Infliximab (IFX) is effective therapy for ulcerative colitis and Crohn's disease, but it may be associated with side effects and loss of response. One loss of response mechanism is increased IFX clearance (IFX-CL), resulting in short half-life and decreased troughs.

METHODS

Patients were recruited, and relevant demographic, clinical, and laboratory data were recorded. IFX serum concentrations and antibodies against IFX (ATI) were measured for therapeutic drug monitoring and modeled using NONMEM.

RESULTS

There were 169 IFX concentrations (Crohn's disease = 73, ulcerative colitis = 92, and diagnosis undetermined = 4). Patient factors significantly associated with high IFX-CL were low albumin, high body weight, and the presence of ATI (P ≤ 0.001). Disease type did not affect IFX-CL. The typical IFX-CL was 0.381 L/d. ATI formation was associated with a 259% increase in IFX-CL. The estimated median IFX effective half-life was 5.6 ± 2.4 days. Patients with low weight are more likely to have low troughs because IFX CL is not linearly related to weight, but IFX dosing is weight-based (in mg/kg). Simulations investigating alternative dose strategies suggested that more reliably measurable concentrations over the dose interval were achieved when the dose interval was shortened than by increasing administered dose.

CONCLUSIONS

IFX-CL is significantly influenced by patient factors, specifically, albumin, body weight, and ATI. There should be a decreasing IFX dose interval strategy, particularly for low albumin patients. Higher starting doses may benefit low body weight patients. Pharmacokinetic models and therapeutic drug monitoring may ensure that patients maintain measurable concentrations throughout dose intervals. Individualized dosing may improve outcomes for IFX-treated patients with Crohn's disease and ulcerative colitis.

A novel protocol allowing oral delivery of a protein complement inhibitor that subsequently targets to inflamed colon mucosa and ameliorates murine colitis

While there is evidence of a pathogenic role for complement in inflammatory bowel disease, there is also evidence for a protective role that relates to host defence and protection from endotoxaemia. There is thus concern regarding the use of systemic complement inhibition as a therapeutic strategy. Local delivery of a complement inhibitor to the colon by oral administration would ameliorate such concerns, but while formulations exist for oral delivery of low molecular weight drugs to the colon, they have not been used successfully for oral delivery of proteins. We describe a novel pellet formulation consisting of cross-linked dextran coated with an acrylic co-polymer that protects the complement inhibitor CR2-Crry from destruction in the gastrointestinal tract. CR2-Crry containing pellets administered by gavage, were characterized using a therapeutic protocol in a mouse model of dextran sulphate sodium (DSS)-induced colitis. Oral treatment of established colitis over a 5-day period significantly reduced mucosal inflammation and injury, with similar therapeutic benefit whether or not the proton pump inhibitor, omeprazole, was co-administered. Reduction in injury was associated with the targeting of CR2-Crry to the mucosal surface and reduced local complement activation. Treatment had no effect on systemic complement activity. This novel method for oral delivery of a targeted protein complement inhibitor will reduce systemic effects, thereby decreasing the risk of opportunistic infection, as well as lowering the required dose and treatment cost and improving patient compliance. Furthermore, the novel delivery system described here may provide similar benefits for administration of other protein-based drugs, such as anti-tumour necrosis factor-α antibodies.

Relationship between vagal tone, cortisol, TNF-alpha, epinephrine and negative affects in Crohn's disease and irritable bowel syndrome

Crohn's disease (CD) and irritable bowel syndrome (IBS) involve brain-gut dysfunctions where vagus nerve is an important component. The aim of this work was to study the association between vagal tone and markers of stress and inflammation in patients with CD or IBS compared to healthy subjects (controls). The study was performed in 73 subjects (26 controls, 21 CD in remission and 26 IBS patients). The day prior to the experiment, salivary cortisol was measured at 8:00 AM and 10:00 PM. The day of the experiment, subjects completed questionnaires for anxiety (STAI) and depressive symptoms (CES-D). After 30 min of rest, ECG was recorded for heart rate variability (HRV) analysis. Plasma cortisol, epinephrine, norepinephrine, TNF-alpha and IL-6 were measured in blood samples taken at the end of ECG recording. Compared with controls, CD and IBS patients had higher scores of state-anxiety and depressive symptomatology. A subgroup classification based on HRV-normalized high frequency band (HFnu) as a marker of vagal tone, showed that control subjects with high vagal tone had significantly lower evening salivary cortisol levels than subjects with low vagal tone. Such an effect was not observed in CD and IBS patients. Moreover, an inverse association (r =  -0.48; p<0.05) was observed between the vagal tone and TNF-alpha level in CD patients exclusively. In contrast, in IBS patients, vagal tone was inversely correlated with plasma epinephrine (r =  -0.39; p<0.05). No relationship was observed between vagal tone and IL-6, norepinephrine or negative affects (anxiety and depressive symptomatology) in any group. In conclusion, these data argue for an imbalance between the hypothalamus-pituitary-adrenal axis and the vagal tone in CD and IBS patients. Furthermore, they highlight the specific homeostatic link between vagal tone and TNF-alpha in CD and epinephrine in IBS and argue for the relevance of vagus nerve reinforcement interventions in those diseases.

Tumour necrosis factor superfamily members in the pathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a group of inflammatory conditions of the gastrointestinal tract of unclear aetiology of which two major forms are Crohn's disease (CD) and ulcerative colitis (UC). CD and UC are immunologically distinct, although they both result from hyperactivation of proinflammatory pathways in intestines and disruption of intestinal epithelial barrier. Members of the tumour necrosis factor superfamily (TNFSF) are molecules of broad spectrum of activity, including direct disruption of intestinal epithelial barrier integrity and costimulation of proinflammatory functions of lymphocytes. Tumour necrosis factor (TNF) has a well-established pathological role in IBD which also serves as a target in IBD treatment. In this review we discuss the role of TNF and other TNFSF members, notably, TL1A, FasL, LIGHT, TRAIL, and TWEAK, in the pathogenesis of IBD.

Therapeutic Drug Monitoring of Anti-TNF Therapy in Inflammatory Bowel Disease

OPINION STATEMENT

While anti-TNF agents have had a marked impact in the treatment of inflammatory bowel disease, a significant number of patients lose their response to these medications over time. Clinical trials have demonstrated that antibodies against anti-TNF medications may impact treatment response and increase the risk of infusion reaction. Scheduled dosing and concurrent use of immunomodulators may help to mitigate these risks via inhibiting the formation of these antibodies. The recent availability of assays to measure anti-TNF drug levels and antibodies against anti-TNFs offer the opportunity to assess patients who have lost response with infliximab and adalimumab, and potentially determine the most appropriate therapeutic strategy. There is growing evidence that such testing improves patient outcomes and is cost-effective, although heterogeneity in the assays used in clinical and observational trials has resulted in mixed results.