Predictors of response to infliximab in patients with Crohn's disease

Infliximab in the treatment of Crohn's disease: predictors of response in an Italian multicentric open study

BACKGROUND

Almost 20% of patients with active Crohn's disease are refractory to conventional therapy. Infliximab is a treatment of proven efficacy in this group of patients and it is not clear which variables predict a good response. AIMS.: To evaluate the role of infliximab looking at the predictors of response in a large series of patients with Crohn's disease.

PATIENTS AND METHODS

Five hundred and seventy-three patients with luminal refractory Crohn's disease (Crohn's Disease Activity Index (CDAI)>220-400) (312 patients) or with fistulising disease (190 patients) or both of them (71 patients) were treated with a dose of 5 mg/kg in 12 Italian referral centres. The primary endpoints of the study were clinical response and clinical remission for luminal refractory and fistulising disease. We evaluated at univariable and multivariable analysis the following variables: number of infusions, sex, age at diagnosis, smoking habit, site of disease, previous surgery, extraintestinal manifestations and concomitant therapies, and type of fistulas.

RESULTS

Patients with luminal refractory disease: 322 patients (84.1%) had a clinical response and 228 (59.5%) reached clinical remission. Patients with fistulising disease: 187 patients (72%) had a reduction of 50% of the number of fistulas and in 107 (41%) a total closure of fistulas was observed. For luminal disease, single infusion (OR 0.49, 95% CI 0.28-0.86) and previous surgery (OR 0.53, 95% CI 0.30-0.93) predicted a worse response for fistulising disease. Other fistulas responded worse than perianal fistulas (OR 0.57, 95% CI 0.303-1.097).

CONCLUSION

In Crohn's disease infliximab is effective in luminal refractory and in fistulising disease. A single infusion and previous surgery predicted a worse response in luminal disease whereas perianal fistulas predicted a better response than other type of fistulas.

The impact of major depressive disorder on the short- and long-term outcome of Crohn's disease treatment with infliximab

BACKGROUND

Major depressive disorder is the most common psychiatric diagnosis in Crohn's disease. In other chronic diseases, evidence suggests that depression influences the course of the disease. Strong evidence of such a mediating role of major depressive disorder in Crohn's disease has never been found.

AIM

To assess the relationship between major depressive disorder and outcome of treatment of luminal Crohn's disease with infliximab.

METHODS

In this prospective study, 100 consecutive unselected patients underwent assessment of psychosocial, demographical disease-related biological and clinical parameters at baseline and at 4 weeks after infliximab. Major depressive disorder was diagnosed using the Patient Health Questionnaire. Subsequently, the patients were followed up clinically until the next flare or during 9 months.

RESULTS

The Crohn's disease responded in 75% of the patients, and remission was achieved in 60%. The presence of major depressive disorder at baseline predicted a lower remission rate (OR = 0.166, 95% CI = 0.049-0.567, P = 0.004). At follow-up, 88% of the patients needed retreatment. At univariate regression analysis, major depressive disorder significantly decreased time to retreatment (P = 0.001). Multivariate Cox regression confirmed major depressive disorder as an independent determinant of active disease both at baseline and at re-evaluation (hazard ratio = 2.271, 95% CI: 1.36-3.79, P = 0.002).

CONCLUSION

Major depressive disorder is a risk factor for failure to achieve remission with infliximab and for earlier retreatment in patients with active luminal Crohn's disease. Assessment and management of major depressive disorder should be part of the clinical approach to patients with Crohn's disease.

Infliximab: Use in Inflammatory Bowel Disease

Crohn's disease (CD) and ulcerative colitis (UC) are chronic and often debilitating inflammatory bowel diseases (IBD) without medical cures. Despite the existence of multiple therapies, the medical treatment of these diseases often has proven insufficient and surgery is frequently required. However, as our understanding of the pathogenesis of these disorders and other immune-mediated inflammatory diseases (eg, rheumatoid arthritis and psoriasis) has grown, new and more specific biologic therapies have been developed that are proving more effective than traditional agents. Infliximab is a genetically engineered monoclonal antibody that targets the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) and represents the first effective biologic therapy for IBD and has largely revolutionized treatment. Infliximab initially was developed to be used in patients with moderate to severe luminal or fistulizing CD who are refractory to standard medical therapy. More and more practitioners now are using infliximab as first-line therapy because of its superior efficacy. Infliximab rapidly induces remission in CD, but when given chronically, it can provide long-term maintenance of remission. In addition, there are some data to support its use as a steroid-sparing agent and treatment for various extraintestinal manifestations of IBD and, although used predominantly to treat CD, recent data suggest that infliximab also may have a role in the management of UC. Overall, infliximab represents a clinically useful, cost-effective therapy that works well, even though careful patient monitoring is required to avoid rare but significant toxicities. The hope is that infliximab, together with other biologic agents that currently are in development, will allow us to modify the course of IBD, avoid complications such as strictures and abscesses, and reduce the need for surgery.

Predictors of response to infliximab in luminal Crohn's disease

AIMS

To identify predictive factors of response to infliximab in luminal Crohn's disease (CD).

PATIENTS AND METHODS

All consecutive patients with luminal CD treated with infliximab between October 1999 and March 2003 in Bordeaux's referral centers were included. All had at least 3 months follow-up post infliximab infusion and no prior treatment with infliximab. Response rates were determined 2 and 8 weeks after infusion according to Crohn's Disease Activity Index (CDAI) (remission=CDAI<150 and response=CDAI decrease more than 100).

RESULTS

Among 44 patients (33 female; mean age 35 +/- 14 yr.), 39 (88%) had a clinical response 2 weeks after infusion (79% in remission). At week 8, the rate of response was 61.4% and exclusive colonic involvement predicted sustained response to treatment (P=0.03). The probability of remission at 56 weeks was 21.4%. Multivariate analysis demonstrated that the only factor associated with response duration was initiating immunosuppressive (IS) therapy in women (RR=3.61 95%CI[1.25-10.41], P=0.017).

CONCLUSION

Exclusive colonic involvement is the only predictive factor of sustained response to infliximab in luminal CD. At the time of infliximab infusion, initiation or modification of IS therapy may favor sustained response, at least in women.

[TNF-alpha inhibitors in inflammatory bowel disease]

Inflammatory bowel disease (IBD) is a chronic immunoinflammatory response to an stimulus that activates a chain of cellular mediators causing intestinal damage. One of the most well recognized proinflammatory mediators involved in the pathogenesis of IBD is tumor necrosis factor alpha (TNFalpha). The treatment of IBD has advanced in parallel to the improvement of the knowledge of its physiopathology, leading to the development of biological therapies. An example of this kind of treatment is the use of substances that antagonize TNFalpha, such as monoclonal antibodies infliximab, adalimumab, natalizumab, etanercept or onercept, with infliximab being the unique approved for use in IBD. Several studies have demonstrated that inhibition of TNFalpha is useful in the treatment of Crohn's disease (CD). In CD, infliximab induces the remission of relapses which are refractory to the conventional treatment, prevents more relapses and induces a closure of enterocutaneous and perianal fistula that do not respond to first line treatment. However, infliximab is not useful in ulcerative colitis. Infliximab treatment has some drawbacks, such as the development of anti-infliximab antibodies, which cause a loss of efficacy of the treatment and hypersensitivity reactions. Other reported adverse effects of infliximab are the development of autoimmunity, such as that related with antinuclear or anti-DNA antibodies, or the reactivation of infections such as tuberculosis. In fact, a screening for tuberculosis is necessary before administration of infliximab. To reduce the adverse effects due to infliximab immunogenicity, several trials with humanized or completely human agents, such as adalimumab or onercept, are under way. Until the precise stimulus that triggers IBD is identified, biological therapies have a great future and the selective antagonism of TNFalpha is already a reality.

Are there predictors of Remicade treatment success or failure?

Infliximab (Remicade) is an antitumor necrosis factor (TNF) therapy effective in both induction and maintenance of remission in Crohn's disease. Identifying predictors of response or relapse to infliximab is important given the potential toxicities and cost of this therapy. Currently available data suggest that concurrent immunosuppressant therapy, certain clinical characteristics, biological and immunological markers, and gene polymorphism may correlate with response to infliximab. However, no single variable has been consistently shown or definitely proven in studies to be a predictor of response to infliximab to be of practical value in current clinical practice. Data from the literature in these areas are reviewed in this article, pointing to the need for additional research in this topic.

Biologic Therapy for Inflammatory Bowel Disease

Despite all of the advances in our understanding of the pathophysiology of inflammatory bowel disease (IBD), we still do not know its cause. Some of the most recently available data are discussed in this review; however, this field is changing rapidly and it is increasingly becoming accepted that immunogenetics play an important role in the predisposition, modulation and perpetuation of IBD. The role of intestinal milieu, and enteric flora in particular, appears to be of greater significance than previously thought. This complex interplay of genetic, microbial and environmental factors culminates in a sustained activation of the mucosal immune and non-immune response, probably facilitated by defects in the intestinal epithelial barrier and mucosal immune system, resulting in active inflammation and tissue destruction. Under normal situations, the intestinal mucosa is in a state of 'controlled' inflammation regulated by a delicate balance of proinflammatory (tumour necrosis factor [TNF]-alpha, interferon [IFN]-gamma, interleukin [IL]-1, IL-6, IL-12) and anti-inflammatory cytokines (IL-4, IL-10, IL-11). The mucosal immune system is the central effector of intestinal inflammation and injury, with cytokines playing a central role in modulating inflammation. Cytokines may, therefore, be a logical target for IBD therapy using specific cytokine inhibitors. Biotechnology agents targeted against TNF, leukocyte adhesion, T-helper cell (T(h))-1 polarisation, T-cell activation or nuclear factor (NF)-kappaB, and other miscellaneous therapies are being evaluated as potential therapies for IBD. In this context, infliximab is currently the only biologic agent approved for the treatment of inflammatory and fistulising Crohn's disease. Other anti-TNF biologic agents have emerged, including CDP 571, certolizumab pegol (CDP 870), etanercept, onercept and adalimumab. However, ongoing research continues to generate new biologic agents targeted at specific pathogenic mechanisms involved in the inflammatory process. Lymphocyte-endothelial interactions mediated by adhesion molecules are important in leukocyte migration and recruitment to sites of inflammation, and selective blockade of these adhesion molecules is a novel and promising strategy to treat Crohn's disease. Therapeutic agents that inhibit leukocyte trafficking include natalizumab, MLN-02 and alicaforsen (ISIS 2302). Other agents being investigated for the treatment of Crohn's disease include inhibitors of T-cell activation, peroxisome proliferator-activated receptors, proinflammatory cytokine receptors and T(h)1 polarisation, and growth hormone and growth factors. Agents being investigated for treatment of ulcerative colitis include many of those mentioned for Crohn's disease. More controlled clinical trials are currently being conducted, exploring the safety and efficacy of old and new biologic agents, and the search certainly will open new and exciting perspectives on the development of therapies for IBD.

Genetic Testing in Crohn Disease

Inflammatory bowel disease (IBD), with its two subforms of Crohn disease and ulcerative colitis, is a polygenic disease that manifests due to environmental trigger factors on the background of a complex genetic predisposition. The first risk gene underlying susceptibility to Crohn disease has been identified as CARD15 (located on chromosome 16q12, encoding NOD2). Three single nucleotide polymorphisms in the leucine rich region (LRR) of this gene are strongly and independently associated with Crohn disease susceptibility and explain up to 20% of the total genetic predisposition for Crohn disease. These variants have been consistently replicated as associated with a particular sub-phenotype characterized by small bowel (ileum) involvement and early age at onset. Presently, genetic testing for the CARD15 variants has only a modest relevance in clinical practice. The most attractive use of genetic testing is for the prediction of response to therapy. Most therapies only show efficacy in subgroups of patients and no clinical parameters are available to distinguish, prior to therapy, whether the patients will be responders or non-responders, or if the patients will experience adverse effects. The pharmacogenetic basis of toxicity is well known for azathioprine: several thiopurine methyltransferase (TPMT) polymorphisms that are associated with reduced activity of this thiopurine drug metabolizing enzyme result in cytotoxic and immunosuppressive adverse effects of azathioprine. Genetic screening, which has found its way into routine clinical diagnostics, allows the identification of the patients who will not tolerate a standard dose of the drug. The extensive search for genetic predictors of response to the anti-tumor necrosis factor treatment with infliximab, which results in a remission rate of 30-40%, has, however, failed to identify a variation associated with a differential response.

The role of pharmacogenomics in the prediction of efficacy of anti-TNF therapy in patients with Crohn's disease

TNF-alpha plays a central role in the pathophysiology of Crohn's disease. Infliximab, a chimeric monoclonal antibody against TNF-alpha, has been shown to be effective and well-tolerated in several large placebo-controlled trials and has become a common treatment for Crohn's disease. The blockade of TNF through the infusion of infliximab is characterized by high clinical efficacy and rapid onset of action. A single infusion of infliximab results in a remission rate of 30-40%. Lack of response appears to be a stable trait even after repeated infusions, suggesting that it might be genetically determined. Mutations in the TNF-alpha gene have been extensively studied as predictors of response with various results. Polymorphisms in the TNF-alpha receptors TNF-R1 and TNF-R2 have been found not to be associated with treatment response. Similarly, the three mutations in the CARD15 gene, which are independently associated with susceptibility to Crohn's disease, have also been found not to be associated with treatment response.

Inflammatory bowel disease and smoking: a review of epidemiology, pathophysiology, and therapeutic implications

The relationship between smoking behavior and inflammatory bowel disease (IBD) is complex. While Crohn's disease (CD) is associated with smoking and smoking has detrimental effects on the clinical course of the disease, ulcerative colitis (UC) is largely a disease of nonsmokers and former smokers. Furthermore, cigarette smoking may even result in a beneficial influence on the course of ulcerative colitis. The potential mechanisms involved in this dual relationship include changes in humoral and cellular immunity, cytokine and eicosanoid levels, gut motility, permeability, and blood flow, colonic mucus, and oxygen free radicals. Nicotine is assumed to be the active moiety. The differential therapeutic consequences comprise the cessation of smoking in CD and, so far, clinical trials using nicotine in different forms of application for UC. In this article, we review the relationship between cigarette smoking and IBD, considering epidemiological, pathogenetic, and clinical aspects.

Perianal Crohn's disease and infliximab therapy

INTRODUCTION

Perianal manifestations occur in almost half of patients with Crohn's disease and often respond poorly to conventional therapies. The introduction of anti-tumour necrosis factor alpha agents (e.g. infliximab) has altered the management of patients who fail first and second line medical and surgical therapies.

METHODS

We performed a literature search of the PubMed database using the Medical Search Headings infliximab, perianal Crohn's disease, fistulae, cost and safety. We also performed a manual search using references from these articles, review articles and proceedings from major gastroenterology meetings.

RESULTS

Use of infliximab, at a dose of 5mg/kg at intervals of 0, 2 and 6 weeks, results in significant improvement in disease in approximately 70% of patients with fistulae. Prior examination under anaesthesia with placement of non-cutting seton sutures in fistula tracks is a useful adjunct in many patients. Preliminary results show a benefit from maintenance infliximab therapy and from concomitant use of immunosuppressants such as azathioprine. No clinical or biochemical markers have been identified which predict non-response to infliximab, although its use is contraindicated in patients with strictures. Acute infusion reactions are the most common side-effect of infliximab therapy and they are usually mild. Despite initial fears, the incidence of opportunistic infection is low. There is inadequate information, at present, regarding a possible increase in incidence of lymphoma with infliximab therapy. Infliximab is expensive compared with established therapies and its use will increase the lifetime cost of treating Crohn's disease.

CONCLUSION

While infliximab is a useful adjunct in selected patients, the cornerstones of management of perianal Crohn's are essentially unchanged.

Austrian infliximab experience in Crohn's disease: a nationwide cooperative study with long-term follow-up

OBJECTIVE

To determine the nationwide experience with infliximab for the treatment of Crohn's disease in Austria.

DESIGN

National multicentre retrospective postal questionnaire survey.

SETTING AND PARTICIPANTS

All institutions using infliximab for Crohn's disease in the years 1999 and 2000 were identified by the registry of the local provider of this drug.

OUTCOME MEASURES

Response after first treatment course according to physician global assessment, number of subsequent infliximab infusions, disease activity at end of follow-up, avoidance of steroids, frequency of surgery for Crohn's disease, and adverse events.

RESULTS

Questionnaires were returned by 32/35 (91%) centres approached. A total of 748 infusions were administered to 153 patients. After the first treatment course an excellent or good response occurred in 48/58 (83%) patients with luminal disease, and in 67/95 (71%) patients with fistulous disease (P < 0.05). After the first treatment course 108 (71%) patients received further infliximab therapy. At a mean follow-up of 29 months, 50% of patients had improved since baseline without requiring surgery for Crohn's disease. Steroid withdrawal was achieved in 25% of patients. Surgery had been performed in one-third of patients and was associated with lacking response to the first treatment course (P < 0.001) and with fistulous disease (P = 0.012). Co-medication with azathioprine favoured the initial response and steroid withdrawal (P < 0.05). One patient died from myocarditis; other adverse events were consistent with that seen in other studies of infliximab.

CONCLUSIONS

The Austrian experience with infliximab for Crohn's disease is in general accordance with results from clinical trials and post-marketing studies from single centres. A substantial subgroup of patients appear to have a prolonged benefit from infliximab therapy.

Smoking and immunomodulators do not influence the response or duration of response to infliximab in Crohn's disease

OBJECTIVE

Clinical predictors for infliximab response are still unknown. Identifying predictors of response to infliximab in Crohn's disease may improve our selection of patients.

METHODS

Two hundred patients with luminal (61%) or fistulous (39%) Crohn's disease and at least 6 months of follow-up following a total of 416 infliximab infusions were evaluated. Clinical response and duration of response were the primary endpoints.

RESULTS

Patients with fistulous disease had a higher response rate (83% versus 70%, P = 0.044) and a significantly longer duration of response compared with patients with luminal disease (17.4 versus 10.1 wks, P = 0.017). For luminal disease, nonsmokers and smokers had similar response rates (74% versus 64%, P = 0.5) and similar durations of response (9.4 wks versus 8.4 wks P = 0.6) while patients taking concurrent immunomodulators had similar response rates compared with those not taking immunomodulators (74% versus 71%, P = 0.9) and similar durations of response (10.4 wks versus 10.6 wks, P = 0.9). For fistulous disease, response rates (89% versus 83% P = 0.9) and duration of response (16.9 wks versus 10.1 wks, P = 0.10) were similar between nonsmokers and smokers and concurrent immunomodulators had no effect on response (89% versus 86%, P = 0.9) or duration of response (19.8 wks versus 15.4 wks, P = 0.46). Multivariable analysis confirmed that neither smoking, corticosteroids, immunomodulator therapy, gender, age, age of disease onset, disease duration, nor luminal disease location significantly influenced response or duration of response.

CONCLUSIONS

Patients with fistulous disease had a higher response rate and a significantly longer duration of response compared with patients with luminal disease. However, among patients with luminal or fistulous disease, neither smoking nor immunomodulators had any effect on response or duration of response.

Tobacco and IBD: relevance in the understanding of disease mechanisms and clinical practice

Current smoking protects against ulcerative colitis and, after onset of the disease, improves its course, decreasing the need for colectomy. However, smoking increases the risk of developing Crohn's disease and worsens its course, increasing the need for steroids, immunosuppressants and reoperations. Smoking cessation aggravates ulcerative colitis and improves Crohn's disease. The effects of smoking are the sum of contradictory effects of various substances, including nicotine and carbon monoxide, and are modulated by gender, genetic background, disease location and activity, cigarette dose and nicotine concentration. Smokers with ulcerative colitis should not be discouraged from stopping smoking but encouraged to stop, to reduce their risk of cardiopulmonary tobacco-related diseases. In Crohn's disease, smoking cessation has become a major therapeutic goal, particularly in young women and in patients with ileal involvement. A large amount of supportive information, use of nicotine-replacement therapies and antidepressants, and individual counselling might aid the patient in quitting.

Treatment of luminal and fistulizing Crohn's disease with infliximab

Infliximab is a novel biologic agent developed from recombinant technology now used widely in the treatment of Crohn's disease. It is effective in inducing and maintaining response in patients with moderate to severe luminal and fistulizing disease refractory to conventional therapy. Infliximab has also been shown to have a steroid-sparing effect. Although safe and generally well tolerated, the drug carries side effects that clinicians need to be able to recognize and to manage properly. Studies are underway to determine the best strategies to avoid antibodies to infliximab and to refine use of the agent.

Optimizing anti-TNF treatment in inflammatory bowel disease

Infliximab, the chimeric monoclonal immunoglobulin (Ig)G1 antibody to tumor necrosis factor (TNF) has changed our therapy of Crohn's disease. Infliximab is indicated in refractory luminal and fistulizing Crohn's disease. In patients with luminal disease, a single intravenous (i.v.) dose of 5 mg/kg is efficacious; in fistulizing disease, an i.v. loading therapy of 5 mg/kg at weeks 0, 2, and 6 is advocated. Because the majority of patients will relapse if not re-treated, a long-term strategy is necessary. The optimal long-term approach is systematic re-treatment with 5 mg/kg every 8 weeks. Episodic therapy on relapse also is possible but is less efficacious and frequently is associated with problems resulting from the formation of antibodies to infliximab (ATI). If treatment is episodic, maintenance therapy with immunosuppression (azathioprine [AZA]/6-mercaptopurine [6-MP] or methotrexate) is mandatory. Trial data suggest that systematic maintenance with 8 weekly doses of infliximab decreases the rate of complications, hospitalizations, and surgeries. These effects probably are achieved thanks to thorough healing of the bowel. Infliximab also is indicated in treating corticosteroid-dependent Crohn's disease and extraintestinal manifestations of Crohn's disease. There are no data yet that support its use as first-line therapy. The data in ulcerative colitis (UC) are conflicting and we should await the results of 2 large controlled trials (ACT1 and ACT2) to position infliximab in the treatment of UC. Other anti-TNF strategies have been less effective than infliximab in the treatment of IBD until now. The results with thalidomide are promising but much more research into small molecules inhibiting TNF and other proinflammatory cytokines is necessary. Safety problems with antibody treatment mainly concern immunogenicity leading to infusion reactions, loss of response, and serum sickness-like delayed infusion reactions. The rate of opportunistic infections is increased mainly in patients treated concomitantly with immunosuppression. Other adverse events associated with anti-TNF strategies are demyelinating disease and worsening of congestive heart failure. Malignancy rates in patients treated with anti-TNF strategies do not seem to be increased.

Infliximab in pediatric ulcerative colitis: two-year follow-up

OBJECTIVES

The role of infliximab in treating pediatric ulcerative colitis (UC) is not defined. The authors previously have described their experience with the open label use of infliximab in nine children with moderate to severe UC. The aim of this study was to describe the outcome of these patients after a minimum 2-year follow-up and to describe the responses of eight additional patients to this medication.

METHODS

The authors reviewed all pediatric patients with UC who received infliximab at The Children's Hospital of Philadelphia from its first use until February 2003. Tolerance of the infusions and adverse events were recorded.

RESULTS

Follow-up information for a minimum of 2 years was reviewed for the nine initial patients. A total of 73 infliximab infusions were administered to these patients. Seven of nine (78%) patients were considered to be responders to the initial dose of infliximab. Two of these patients became nonresponders within 9 months of the first dose of infliximab and underwent colectomy. Of the remaining five (56%) patients with sustained response, two continue to receive infliximab infusions and three are doing well without infliximab. One patient experienced an infusion reaction, and one experienced herpes zoster infection. We have treated eight additional UC patients with infliximab. Seven (88%) patients were considered responders. One responder experienced relapse within 2 months. Overall, a short-term improvement was seen in 14 of 17 (82%) patients, and sustained improvement in 10 of 16 (63%) patients followed up for more than 9 months. All five patients with severe or fulminant UC, unresponsive to 2 weeks of intravenous corticosteroid therapy, experienced improvement with infliximab. Infliximab was well tolerated.

CONCLUSION

Infliximab is associated with short- and long-term clinical improvement in children and adolescents with moderate to severe UC.

Association between polymorphism in IgG Fc receptor IIIa coding gene and biological response to infliximab in Crohn's disease

AIM

To test the hypothesis of an association between polymorphism in FCGR3A (the gene coding for FcgammaRIIIa, which is expressed on macrophages and natural killer cells, is involved in antibody-dependent cell-mediated cytotoxicity and has recently been associated with a positive response to rituximab, a recombinant immunoglobulin G1 antibody used in non-Hodgkin's lymphomas) and response to infliximab in Crohn's disease.

METHODS

FCGR3A-158 polymorphism was determined using an allele-specific polymerase chain reaction assay in 200 Crohn's disease patients who had received infliximab for either refractory luminal (n = 142) or fistulizing (n = 58) Crohn's disease. Clinical and biological responses (according to C-reactive protein levels) were assessed in 200 and 145 patients, respectively.

RESULTS

There were 82.9% clinical responders in V/V patients vs. 72.7% in V/F and F/F patients (N.S.). Globally, the decrease in C-reactive protein was significantly higher in V/V patients than in F carriers (P = 0.0078). A biological response was observed in 100% of V/V patients, compared with 69.8% of F carriers (P = 0.0002; relative risk, 1.43; 95% confidence interval, 1.27-1.61). In the sub-group of patients with elevated C-reactive protein before treatment, the multivariate analysis selected the use of immunosuppressive drugs and FCGR3A genotype as independent factors influencing the clinical response to infliximab (P = 0.003).

CONCLUSION

Crohn's disease patients with FCGR3A-158 V/V genotype have a better biological and, possibly, clinical response to infliximab.

The biology of TNF blockade

Rheumatoid arthritis and Crohn's disease are costly diseases that result in significant long-term patient disability. They are chronic inflammatory diseases that are associated with increased production of Tumor Necrosis Factor (TNF). Blockage of this cytokine with bio-engineered compounds has significantly changed therapy of these diseases and has ushered in the era of biological therapy. The pro-inflammatory role of TNF is mediated by its essential respiratory burst function that is effectively inhibited by anti-TNF therapy. Anti-TNF therapy is effective in approximately two-thirds of patients to whom it is administered, but the effect is temporary. Lack of response to anti-TNF therapy stems from interplay of host-factors including: host cytokine response, disease phenotype, and antibody response to the anti-TNF agents. NOD 2, a defect present in approximately 50% of Crohn's disease patients, bears no relationship to non-response. Additionally, TNF promoter gene polymorphisms and TNF receptor gene heterogeneity play a significant role in non-response and disease course/severity. Adverse effects of anti-TNF therapy include early and delayed hypersensitivity reactions, cell-mediated infections, lupus-like syndrome, demyelinating diseases, and exacerbation of CHF.

Clinical and radiological responses after infliximab treatment for perianal fistulizing Crohn's disease

OBJECTIVES

Infliximab is an effective therapy for fistulizing Crohn's disease of the perineum. We sought to determine whether the clinical improvement after infliximab is associated with radiological closure of fistula tracts.

METHODS

Clinical responses and radiological imaging studies by transperineal ultrasound were evaluated in 35 patients with Crohn's disease perianal fistulas after treatment with infliximab 5 mg/kg up to 48 wk. Paired comparison of baseline and follow-up imaging studies at 8 wk and at 56 wk or discontinuation were assessed by an imaging score of perianal fistula severity, based on the Parks criteria. Complete clinical fistula closure and radiological healing were primary outcome measures.

RESULTS

At 8 wk, after two infusions of infliximab at 0 and 2 wk, clinical fistula closure occurred in 49% of patients. The radiological score at 8 wk was higher for patients with clinical fistula closure than for patients with no clinical improvement (p= 0.023) and two patients showed complete radiological healing. At 56 wk, clinical fistula closure occurred in 46% patients. Clinical fistula scores correlated with radiological scores (R2= 0.52; p < 0.001) but were not associated with fistula complexity, number of fistulas, or number of collections at baseline imaging. The proportion of patients with marked radiological improvement increased from 14% at 8 wk to 43% at 56 wks (p= 0.015) and complete radiological healing occurred in 4 (11%) patients.

CONCLUSIONS

For perianal fistulizing Crohn's disease, repeat dose infliximab improves clinical and radiological outcomes, although complete radiological healing occurs in a minority of patients.

Drug interaction between infliximab and azathioprine in patients with Crohn's disease

BACKGROUND

A drug interaction has been observed between infliximab and methotrexate in rheumatoid arthritis.

AIM

To look for an interaction between infliximab and azathioprine in Crohn's disease patients using the active metabolites of azathioprine: 6-tioguanine nucleotides.

METHODS

Patients receiving azathioprine who required infliximab for ileo-colonic or ano-perineal Crohn's disease were recruited prospectively. 6-tioguanine nucleotide levels were evaluated before infusion, within 1-3 weeks after the first infusion and 3 months after the first infusion. The clinical outcome was evaluated by the Harvey-Bradshaw index or the closure of ano-perineal fistulas.

RESULTS

Thirty-two patients were included (17 received one infusion and 15 received three infusions). The mean 6-tioguanine nucleotide level was comparable before and 3 months after the first infusion, but a significant increase was observed within 1-3 weeks after the first infusion (P < 0.001). In parallel, a significant decrease in leucocyte count and increase in mean corpuscular volume were observed; these modifications were normalized 3 months after infusion. An increase in 6-tioguanine nucleotide level of greater than 400 pmol/8 x 108 erythrocytes was strongly related to good tolerance and a favourable response to infliximab, with a predictive value of 100%.

CONCLUSIONS

This prospective study provides evidence for a drug interaction between azathioprine and infliximab.

Infliximab in the treatment of medically refractory indeterminate colitis

AIM

To examine the outcome of infliximab intervention in refractory indeterminate colitis.

METHODS

Twenty patients with severe, medically refractory indeterminate colitis were treated with infliximab. All patients initially received infliximab, 5 mg/kg, intravenously and, in some patients, the dose was subsequently increased to 10 mg/kg. The number of infusions ranged from one to 16 per patient. Indeterminate colitis was defined as colitis that could not be classified with certainty as Crohn's disease or ulcerative colitis based on traditional clinical, endoscopic and histopathological criteria. The clinical response to infliximab was classified as complete response, partial response or non-response.

RESULTS

Fourteen of the 20 patients (70%) showed a complete response to infliximab treatment, two showed a partial response and four showed no response. The four non-responders underwent colectomy with ileal pouch-anal anastomosis. The resected colon specimen was consistent with ulcerative colitis in all four cases, although two were subsequently re-classified as Crohn's disease. Eight additional patients were subsequently re-classified as having Crohn's disease on longer follow-up evaluation, whilst eight continued to have features of indeterminate colitis. The response rate to infliximab treatment was similar in both groups.

CONCLUSIONS

Infliximab is effective in approximately two-thirds of patients with indeterminate colitis, and thus may be considered for patients with refractory disease prior to colectomy. The follow-up time afforded by infliximab treatment may allow for more accurate classification of the disease in a significant proportion of patients whose colitis has indeterminate features at initial presentation.

Management of Crohn's disease of the ileoanal pouch with infliximab

OBJECTIVES

The occurrence of Crohn's disease (CD) in a patient with an ileal-pouch anastomosis (IPAA) often results in severe morbidity and significant chance of reservoir loss. We report our experience of the use of infliximab in these patients.

METHODS

Medical records of 26 patients with an IPAA and CD-related complications were reviewed. The median time between the IPAA and the diagnosis of CD was 4.5 yr (range 0.1-16 yr). The main reasons for changing the original ulcerative colitis diagnosis to CD were complex perianal or pouch fistulizing disease in 14 patients (54%), prepouch ileitis in five (19%), and both prepouch ileitis and complex fistula in seven (27%). Patients received one to three doses of infliximab over 8 wk as induction therapy. Subsequently the patients received a variable number of maintenance infusions.

RESULTS

At a short term follow-up, 16/26 patients (62%) had a complete response, six of 26 (23%) had a partial response, and four of 26 (15%) had no response. Information regarding long term follow-up was available in 24 patients. After a median follow-up of 21.5 months (range 3-44 months), eight patients (33%) either had their pouch resected or had a persistent diverting ileostomy. The pouch was functional in 16/24 (67%) patients, with either good (n = 7) or acceptable (n = 7) clinical results in 14/24 (58%). Of those 14 patients, 11 were under long term, on demand, or systematic maintenance treatment with infliximab.

CONCLUSIONS

Infliximab is beneficial in both the short and long term treatment of patients with an IPAA performed for a presumed diagnosis of ulcerative colitis who subsequently develop CD-related complications. Good pouch function requires long term treatment with infliximab in most patients.

An analysis of factors influencing short-term and sustained response to infliximab treatment for Crohn's disease

BACKGROUND

59-81% of patients given infliximab for Crohn's disease will respond. Although now in widespread use, little consensus exists regarding the optimal place in patient care. Recently developed guidelines have identified need for markers that predict response.

AIMS

We aimed to identify markers of response to infliximab given for Crohn's disease.

METHODS

Markers of response (defined at 4 weeks) were prospectively assessed in 74 infliximab-treated patients with Crohn's disease. Patients were followed-up to 1 year.

RESULTS

Fifty-four of 74 (73%) patients responded. Univariate analysis identified that smokers were less likely to respond than non-smokers [P = 0.005, odds ratio (OR) 0.22]. Patients established on immunosuppression (P = 0.034, OR 7.31) and with isolated colonic disease (P = 0.042, OR 3.83) were more likely to respond. Multiple logistic regression confirmed smoking (P = 0.035, OR 0.24) and colonic disease (P = 0.035, OR 4.87) as independent markers of response. One-year relapse rates differed significantly between smokers and non-smokers (100% vs. 39.6%, P = 0.0026, relative risk 3.2) and between patients established on immunomodulators or not (58.0% vs. 92.8%, P = 0.0054, relative risk 2.6).

CONCLUSIONS

Smoking has a strong adverse effect on the response rates and maintenance of response to infliximab. Patients on immunomodulators have a more favourable short- and long-term response. These results have important implications for clinical practice.

Recent advances in immunomodulation in the treatment of inflammatory bowel disease

This review in depth considers the thiopurines azathioprine, 6-mercaptopurine and 6-thioguanine, methotrexate, ciclosporin, infliximab and less well-established immunomodulators (including thalidomide, mycophenolate, tacrolimus and natalizumab among others) in their role of modifying the course of ulcerative colitis and Crohn's disease. The five papers are preceded by an overview on the therapeutic order of precedence, the indications and duration of therapy, as well as future concepts.