Early or late guided missile in the treatment of Crohn's disease?

Production, characterization, and application of a monoclonal antibody specific for the extracellular domain of human P2X7R

This paper focuses on the production of a high-affinity monoclonal antibody (mAb) that can efficiently detect and block purinergic ligand-gated ion channel 7 receptor (P2X7R). To achieve this goal, the extracellular domain of human P2X7R, P2X7R-ECD, was used as an immunogen for BALB/c mice, inducing them to produce spleen lymphocytes that were subsequently fused with myeloma cells. Screening of the resultant hybridoma clones resulted in the selection of one stable positive clone that produced a qualified mAb, named 4B3A4. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis demonstrated that the purity of the purified 4B3A4 mAb was above 85%, with prominent bands corresponding to molecular weights of 55 kDa (heavy chain) and 25 kDa (light chain), and the BCA assay showed that the concentration of the purified 4B3A4 mAb was 0.3 mg/mL. Western blot analysis revealed that the 4B3A4 mAb could specifically recognize and bind both P2X7R-ECD and the full-length P2X7R protein. Laser scanning confocal microscopy (LSCM) revealed that the 4B3A4 mAb specifically bound to P2X7R on the membrane of human peripheral blood mononuclear cells (PBMCs). P2X7R expression was significantly different between healthy individuals and people with certain cancers as determined by flow cytometry (FCM). In addition, the 4B3A4 mAb significantly reduced ATP-stimulated Ca²⁺ entry and YO-PRO-1 uptake, which indicated that the 4B3A4 mAb effectively blocked P2X7R activity. These data indicate that the 4B3A4 mAb can be further used as not only an antibody to detect cell surface P2X7R but also as a therapeutic antibody to target P2X7R-related signaling pathways.

Top-down or step-up treatment in Crohn's disease?

In recent years, a change in the treatment goals for patients with Crohn's disease (CD) has come under intense discussion. Whereas 10 years ago treatment was initiated mainly in reaction to acute flares of the disease aimed to improve clinical symptoms, the focus now has changed to the prevention of damage to the intestinal wall. The prevention of structural damage by achievement of 'mucosal healing', however, is associated with the more 'aggressive' treatment and an earlier use of immunosuppressants and biologicals. The use of immunosuppressants and biologicals especially in patients with CD has decreased the rates of surgery and hospitalizations, indicating that there is a group of patients definitely profiting from such an early use of immunosuppressive treatment. In this group of patients, the benefits outweigh the disadvantages of immunosuppression: the increased risk of severe infections. However, it remains questionable whether this improvement can only be achieved by completely reversing established treatment strategies. The dispute has been condensed to the questions whether 'top-down' (e.g. start with a combination of biological and immunosuppressant and 'de-escalate' if possible) or 'step-up' treatment (e.g. start with topical steroids, step up to systemic steroid, go to immunosuppression and biologicals if necessary) may be better. In general, in an upcoming era of individualized and personalized medicine, a 'one-size-fits-all' approach does not appear to be desirable. CD patients definitely should not be undertreated (which is still frequently the case) or remain on steroid treatment (which is inappropriate); however, overtreatment (putting patients at risk of side effects without benefit) is against a fundamental principle of medicine: nihil nocere (do no harm).

Biological therapies for inflammatory bowel disease: controversies and future options

Over the last few years, advances in understanding the pathogenesis of inflammatory bowel disease, together with progress in biotechnology, have led to the availability of several biological drugs that have dramatically changed the therapeutic approach to these disorders. Indeed, several molecules targeting crucial inflammatory cytokines, blocking T-cell activation/proliferation or the recruitment of inflammatory cells into the inflamed bowel, have been discovered and commercialized. However, the increasing use of biological agents has raised some concerns regarding their short- and long-term safety. This review offers a critical evaluation of the efficacy and safety of biological agents in the management of both Crohn's disease and ulcerative colitis. In addition, promising therapeutic options are discussed.

Recent advances in the management of Crohn's disease

In the last 10 years many advances have been achieved in the treatment of patients with Crohn's disease, particularly in the field of biological agents. Infliximab, a tumour necrosis factor alpha antagonist, has been recently added to the therapeutic armamentarium for Crohn's disease and has greatly improved our treatment options. Infliximab has demonstrated efficacy in the induction and maintenance of remission in luminal and fistulizing Crohn's disease both in adults and children. However, the potential development of autoantibodies and the risk of serious adverse events limit the possibility of a wider use of infliximab. Searching for less immunogenicity and higher effectiveness in the last years a number of biological agents have been developed. Adalimumab, a fully human monoclonal antibody anti tumour necrosis factor alpha, has resulted effective and safe in patients with Crohn's disease, both naive and refractory to infliximab, presenting also the advantage of subcutaneous way of administration. Natalizumab also showed promising results in terms of efficacy but its safety is still under investigation. To date no particular advances have been recently appeared in the literature concerning conventional immunosuppressive drugs. Surgery remains a valid resort for refractory patients. Autologous stem cell transplantation represents a new hope as rescue treatment for patients with severe refractory Crohn's disease.

Infliximab in Crohn's disease: early and long-term treatment

The natural history of Crohn's disease is characterized by a remitting and relapsing course that progresses to complications and surgery in the majority of patients. Current treatment guidelines advocate a stepwise approach according to disease location and severity at presentation, with goals mainly aimed at inducing and maintaining clinical remission. Major advances in the understanding of the pathogenesis of Crohn's disease offered significant opportunities for the development of new therapies over the past years. Infliximab and other biologic agents have shown impressive results in Crohn's disease patients refractory to standard therapy, suggesting a potential disease course-modifying action. These led to the proposal to reverse the traditional therapeutic algorithms using these agents early in the course of the disease. Preliminary data suggest that early intervention may be a more effective treatment strategy in some Crohn's disease patients. As yet, early and indiscriminate use of biologics remains to be supported by convincing evidence. Data on long-term treatment of Crohn's disease with infliximab or other biologics are even more scarce. Future studies aimed to identify predictors of complicated disease and long-term randomized studies aimed to compare "step-up" and "top-down" strategies in high-risk groups should help to answer if early introduction of biological therapy alters the natural history of Crohn's disease.

Treatment of inflammatory bowel disease: a review of medical therapy

Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory diseases of the gastrointestinal tract. While a cure remains elusive, both can be treated with medications that induce and maintain remission. With the recent advent of therapies that inhibit tumor necrosis factor (TNF) alpha the overlap in medical therapies for UC and CD has become greater. Although 5-ASA agents have been a mainstay in the treatment of both CD and UC, the data for their efficacy in patients with CD, particularly as maintenance therapy, are equivocal. Antibiotics may have a limited role in the treatment of colonic CD. Steroids continue to be the first choice to treat active disease not responsive to other more conservative therapy; non-systemic steroids such as oral and rectal budesonide for ileal and right-sided CD and distal UC respectively are also effective in mild-moderate disease. 6-mercaptopurine (6-MP) and its prodrug azathioprine are steroid-sparing immunomodulators effective in the maintenance of remission of both CD and UC, while methotrexate may be used in both induction and maintenance of CD. Infliximab and adalimumab are anti-TNF agents approved in the US and Europe for the treatment of Crohn's disease, and infliximab is also approved for the treatment of UC.

The effect of medical treatment on patients with fistulizing Crohn's disease: a retrospective study

BACKGROUND

Fistulas are a major complication of Crohn's disease (CD), but the treatment strategy for fistulizing Crohn's disease is controversial. The aim of this study is to analyze the efficacy of medical therapy for fistulizing Crohn's disease.

METHODS

Therapeutic regimens and clinical outcome of medical therapy were evaluated in 10 patients with fistulizing Crohn's disease (6 with external fistulas, 4 with internal fistulas). Complete response was defined as fistula closure with complete arrest of drainage in cases of external fistula, and disappearance of the fistula demonstrated by imaging studies in cases of internal fistula. Clinical remission was defined as a Crohn's disease activity index of less than 150 points.

RESULTS

Complete responses were observed in all 6 patients with external fistulas (4 patients treated with a combination of antibiotics and immunomodulators, and 2 also treated with infliximab). In contrast, fistula closure was observed in only 1 of 4 patients with internal fistulas. Clinical remission of CD was achieved in all patients with external fistulas, whereas there was no significant difference in the CD activity index before and after medical therapy in patients with internal fistulas.

CONCLUSIONS

External fistulas were more responsive to medical therapy than internal fistulas in patients with CD. Combined treatment with antibiotics and immunomodulators might be a suitable initial therapy for CD patients with external fistulas, and infliximab can be used as an additional therapy in cases refractory to this combination therapy. However, randomized controlled studies will be required to investigate what kinds of therapies are optimal for CD patients with fistulas.

Late-breaking news from the "4th International Meeting on Inflammatory Bowel Diseases" Capri, 2006

At the "4th International Meeting on Inflammatory Bowel Diseases: on the Way to New Therapies," Capri, 2006, genetics, bacteria-host interactions, immunomodulation, and tissue response were discussed deeply in order to understand, rationalize, and develop novel therapies. About genetics, the importance of a better understanding of the nature of known loci and of the putative associations was stressed. It was confirmed that genotype-phenotype associations in inflammatory bowel disease (IBD) have important clinical and therapeutic implications. The importance of the search for dominant bacterial antigens in chronic immune-mediated intestinal inflammation emerged, as well as knowledge of cellular and molecular mechanisms of bacterial-host interactions. It was discussed how innate and adaptive immunity signaling events can perpetuate chronic inflammation. Signal transduction pathways provide an intracellular mechanism by which cells respond and adapt to environmental stress. The identification of these signals have led to a greater understanding of the pathogenesis of IBD and pointed to potential therapeutic targets. It was shown that immune homeostasis is lost in IBD, resulting in a complex tissue response involving the action of immune and nonimmune cells. The nonimmune tissue response in IBD could be regarded as a new target for control of chronic intestinal inflammation. The changing role of biotherapy in IBD was widely discussed and in particular the anti-TNF-alpha monoclonal antibodies. Granulocyte-colony stimulating factor (GM-CSF) and stem cells therapies were also discussed. The risk-to-benefit ratio of the novel therapies was analyzed in detail. Finally, future directions for basic science and the unmet needs for clinical practice were presented.

Infliximab Therapy in Children and Adolescents with Inflammatory Bowel Disease

This review summarises the present knowledge of infliximab therapy in children with inflammatory bowel disease (IBD) based on the available published literature. Infliximab, the chimeric monoclonal IgG(1) antibody to tumour necrosis factor-alpha, is indicated for medically refractory luminal and fistulising paediatric Crohn's disease. Recently, ulcerative colitis case series in children and adolescents suggested that infliximab might also be effective for treatment of ulcerative colitis resistant to standard medical therapy. Induction therapy with infliximab 5 mg/kg at weeks 0, 2 and 6 is routinely used. Since the majority of patients will relapse if not re-treated, a long-term approach with systematic re-treatment with 5 mg/kg every 8-12 weeks is recommended. Maintenance therapy every 8 weeks was superior to 12 weeks' administration in maintaining response and remission in the largest-to-date paediatric randomised trial. Concomitant immunosuppressive therapy reduces the risk of infliximab antibody formation and infusion reactions, and prolongs the duration of treatment success. Severe reactions may not be an absolute contraindication to future infliximab therapy. Premedication does not prevent the development of infusion reactions; however, it is indicated for prevention of subsequent infusion reactions. Adverse events and safety findings in children are comparable to those observed in adults. Latent tuberculosis needs to be screened for. Malignancy rates in paediatric patients treated with infliximab do not seem to be increased. However, newly reported cases of hepatosplenic T-cell lymphoma in young patients with IBD treated with infliximab and mercaptopurine therapy raise concern, and long-term follow-up studies are necessary to determine the true malignancy risk.