Tolerability of interferon alpha-2b, a possible new treatment of active Crohn's disease

Development and validation of a patient-reported disability measurement tool for patients with inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease can impact on a patient's ability to maintain normal physical and mental function, and fulfil their social, family and work roles. Aspects of disability in IBD have received little attention.

AIM

To develop, validate and apply a questionnaire directed towards evaluating these disease aspects.

METHODS

A literature review on disability in IBD was undertaken, and opinion about aspects of disability to measure was sought from six IBD-specialised gastroenterologists. A questionnaire was developed, and IBD patients completed the new disability questionnaire, the SF-36 and the short-IBD (SIBDQ - 10 point). A subgroup of patients completed the questionnaire again 4 weeks later. Healthy volunteers were studied as a control group.

RESULTS

A total of 116 IBD out-patients were approached, of whom 81 (52 Crohn's disease and 28 ulcerative colitis) participated. Nineteen patients were re-evaluated at 4 weeks. Twenty-five controls were studied. All subscales demonstrated good Cronbach's alpha reliability and reproducibility. There was a significant inverse correlation between the disability score and the SIBDQ and between the disability score and the SF36 and a positive correlation with the Crohn's Disease Activity Index (CDAI) (all P < 0.001). Disability differed between ulcerative colitis and controls, but not between active and inactive disease.

CONCLUSIONS

The new disability questionnaire is sensitive for detecting disability, is reliable and reproducible, and correlates with disease activity in Crohn's disease, but not ulcerative colitis. Further prospective testing is now needed in the longer term, larger patient populations and in different countries and ethnicities.

Cytokines in inflammatory bowel disease

Over the past decade, much has been learned regarding the role of various cytokines in the pathogenesis of inflammatory bowel disease. Several cytokine ‘knockout’ models in mice have been shown to develop colitis, while alterations in the production of various cytokines has been documented in human Crohn's disease and ulcerative colitis. In recent years, attempts have been made to treat these diseases through modulation of cytokine production or action. This review focuses on the cytokines that have been implicated in the pathogenesis of inflammatory bowel disease. The evidence for and against a role for particular cytokines in intestinal inflammation is reviewed, as is the experimental and clinical data suggesting that cytokines are rational targets for the development of new therapies.

New and emerging biologics in the treatment of inflammatory bowel disease: quo vadis?

Inflammatory bowel diseases (IBD) are pathological conditions characterized by chronic inflammation that is primarily the consequence of dysregulation of the immune response. Over the last decade, the advances in the pathophysiology of IBD have paved the way for the development of a number of biological agents that selectively target specific molecules and/or pathways involved in gut inflammation. Although numerous, so far, the only biological therapeutics that are approved for the treatment for IBD are monoclonal antibodies against tumor necrosis factor alpha. This paper systematically reviews the mechanismof-action, efficacy, short-term and, where available, long-term safety of biological agents that target molecules other than tumor necrosis factor alpha, in IBD.

Safety of biologic therapy

Several biologic agents have been assessed in patients with inflammatory bowel disease (IBD; Crohn's disease [CD] and ulcerative colitis [UC]). Until recently, only infliximab (humanized monoclonal anti-TNF-alpha antibody) had been approved by the Food and Drug Administration (FDA) to induce and maintain remission in patients with active mild to moderate and/or fistulizing Crohn's disease who are refractory to conventional therapy. Two recent trials, ACT 1 and ACT2, observed high efficacy of infliximab in inducing and maintaining clinical remission, mucosal healing, and corticosteroid-sparing effects in patients with moderate to severe UC. This agent also was recently approved by the FDA for the treatment of ulcerative colitis to reduce signs and symptoms, to induce clinical remission and healing of the intestinal mucosa, and to eliminate the use of corticosteroids in patients with moderately to severely active UC who have had an inadequate response to conventional therapy. There have been many randomized, double-blind, controlled and open-label uncontrolled studies of large and small numbers of patients assessing the efficacy and safety of various biologic agents considered potentially useful in the treatment of IBD. Among all the biologic agents, infliximab has the most robust data on safety. This is because it has been evaluated in many more trials than has any other biologic agent. In addition, postmarketing experience provides very valuable information about adverse events occurring during treatment with this agent.

Complications of biological therapy for inflammatory bowel diseases

PURPOSE OF REVIEW

The purpose of this review is to analyze the complications associated with treatment of inflammatory bowel disease with biologic agents.

RECENT FINDINGS

There have been various biologic agents evaluated in patients with inflammatory bowel disease; that is, Crohn's disease and ulcerative colitis. Thus far only infliximab has been approved by the US Food and Drug Administration as induction and maintenance treatment in patients with active Crohn's disease (moderate-to-severe and/or fistulizing) who are refractory to conventional therapy. Recent data from two large multicenter, multicountry, randomized controlled clinical trials have demonstrated that infliximab is efficacious also for the treatment of ulcerative colitis. Other biologics considered potentially efficacious are still undergoing evaluation in various clinical trials.

SUMMARY

The data concerning biologics' associated toxicity in patients with inflammatory bowel disease are the most robust in the case of infliximab. These data are derived from both prospective, randomized clinical trials and from post-marketing experience. In the case of the remaining agents the data concerning safety in inflammatory bowel disease are limited, as these agents were not evaluated in as many trials as infliximab; indeed, some of them included only several patients.

Advances in gastrointestinal pharmacotherapy

The medical management of patients with gastrointestinal diseases is advancing rapidly. At a recent symposium held during Digestive Disease Week in Chicago in May of 2005, specific attention was given to the future prospects for medical management of 3 common gastrointestinal disease areas: antisecretory therapy, chronic hepatitis C, and inflammatory bowel disease. Antisecretory approaches include drug combinations including a proton pump inhibitor, potassium competitive acid blockers, and antigastrin agents. The latter two classes are still experimental, but the former combinations have potential to enhance the highly effective agents currently available. The focus of treatment advances in chronic hepatitis C in the immediate future is the discovery of more effective treatment regimens for nonresponders to prior therapy, who are becoming the largest group of patients seeking treatment of hepatitis C. The combination of peginterferon with ribavirin results in 6%-15% sustained virologic response rates in patients who were prior nonresponders to standard interferon plus ribavirin. Newer strategies to eradicate hepatitis C virus infection using different interferons, such as interferon alfacon-1 or higher doses of peginterferon, or long-term maintenance peginterferon, are undergoing study and show promise based on data from preliminary studies. Several immunomodulators have promise in inflammatory bowel disease, although the risk-benefit ratio and costs of therapy require evaluation. Nevertheless, the success of new biologics such as anti-TNFalpha agents augurs well for effective future therapies.

Crohn's disease: an immunodeficiency?

Autoimmunity appears to be a key factor in Crohn's disease as it develops in a genetically susceptible host if the immunological tolerance towards bacterial antigens within the gastrointestinal tract is abrogated. The resulting excessive immunological activity leads to a chronic sometimes transmural inflammatory process within the bowel wall. However, several lines of evidence are compatible with an immunodeficiency preceding these processes: humoral or cellular immune defects can predispose to inflammatory bowel disease. An increased bacterial adherence at the intestinal mucosa, which is possibly attributable to impaired expression of defensins was observed in Crohn's disease. Furthermore, the 3020insC mutation of the NOD2/CARD15 gene which is associated with Crohn's disease results in impaired cytokine transcription. Lastly, therapeutic approaches such as the use of antibiotic therapy or granulocyte macrophage colony stimulating factor are in line with the concept of an immunodeficiency being a crucial element in Crohn's disease.

Biologic therapy of inflammatory bowel disease

Advancing knowledge regarding the biology of chronic inflammation has led to the development of specific biologic therapies that mechanistically target individual inflammatory pathways. Many biologic therapies are being evaluated for the treatment of the chronic inflammatory bowel diseases, Crohn's disease and ulcerative colitis. Biologic compounds proven to be effective for Crohn's disease include monoclonal antibodies to tumor necrosis factor (infliximab and CDP571) and to the leukocyte adhesion molecule alpha4 integrin (natalizumab). Other biologic compounds for which there is insufficient evidence to judge efficacy for inflammatory bowel disease include: p55 tumor necrosis factor binding protein (onercept); interferon alpha; interferon beta-1a; anti-interferon gamma antibody; anti-interleukin 12 antibody; p65 anti-sense oligonucleotide (blocks NF-kappaB); granulocyte colony stimulating factor, and granulocyte macrophage colony stimulating factor; anti-interleukin 2 receptor antibody; epidermal growth factor; keratinocyte growth factor 2 (repifermin); human growth hormone; anti-CD4 antibody; and anti-alpha4beta7 antibody. Biologic therapies that have been proven ineffective for inflammatory bowel disease include: interleukin 10; interleukin 11; anti-sense intercellular adhesion molecule-1; and the tumor necrosis factor receptor fusion protein etanercept. Based on the early successes of infliximab, CDP571 and natalizumab, it seems certain that biologic therapy will play an important role in the future treatment of inflammatory bowel disease.

Novel therapies for inflammatory bowel disease

Looking back at successes and failures in newer approaches to treating IBD, it is tempting--although still difficult--to draw conclusions about pathogenesis. When a therapy proves effective, do clinicians truly know how it works? Even with a therapy as specific as anti-TNF antibody, it is not clear if the benefit is attributable to simple binding and clearance of TNF-alpha or to binding on the cell surface and subsequent deletion of the activated macrophage. When a drug appears to be less effective than preclinical models suggest, can failures in effectiveness from delivery or dosing be differentiated? The disappointing results of clinical trials with IL-10--so at odds with the prediction of benefit from animal models--bring into question the validity of those models as well as the soundness of design of the clinical trials on which efficacy of IL-10 is judged. The variability of response even to the most narrowly targeted agents suggests that these diseases are far more heterogeneous in humans than in their murine counterparts. Clinicians are only just beginning to recognize subclinical markers of response, and it may soon be possible to predict response on the basis of genetic composition. For the moment, however, the field of pharmacogenetics is embryonic. Challenges in developing new therapeutic strategies include not only identifying novel agents, but also improving the definitions of clinical endpoints and defining efficacy at the biologic level. Only through considered evaluation of clinical evidence may clinicians determine which therapies should remain novelties and which should become an accepted part of the armamentarium.

Medical therapy of active Crohn's disease

Active Crohn's disease constitutes a major problem in gastroenterology. Symptoms vary with site, extent and local complications of the disease as well as with the absence or presence of extraintestinal manifestations. Due to the troublesome consequences of the disease new treatments have continuously been tried. However, the results have varied and no definite breakthrough has occurred in the medical treatment of active Crohn's disease during the last years. The new salicylates have shown some effect using higher doses, but have not fulfilled the expectations once connected with their development. The new steroids have compared well to, but not exceeded, the older corticosteroid preparations in terms of therapeutic efficacy but they have a better side-effect profile. The role of the purine analogs azathioprine/6-mercaptopurine has been further evaluated. The onset of their effect is slow, an intravenous loading dose might shorten this time span, and they are steroid sparing. The controlled data on methotrexate are limited and the long-term effects not well studied and there is concern about toxicity. Even the use of cyclosporine in active Crohn's disease is controversial and connected with serious adverse events. Studies on the new immune modulating therapies such as anti-TNF-alpha antibodies, anti-CD4 antibodies, interleukin-10 and interferon have been encouraging but large scale studies are still awaited before the effect and the spectra of side-effects can be fully evaluated. The aim of this chapter is to summarize the present knowledge of medical treatment of active Crohn's disease and to point towards the directions of new therapeutic options.