Thalidomide therapy for patients with refractory Crohn's disease: an open-label trial

Pharmacogenetics of inflammatory bowel disease

The therapeutic efficacy and toxicity of many commonly employed drugs show interindividual variations that relate to several factors, including genetic variability in drug-metabolizing enzymes, transporters or targets. The study of the genetic determinants influencing interindividual variations in drug response is known as pharmacogenetics. The ability to identify, through preliminary genetic screening, the patients most likely to respond positively to a medication should facilitate the best choice of treatment for each patient; drugs likely to exhibit low efficacy or to give negative side-effects can be avoided. Among the medications used for inflammatory bowel disease, the best studied pharmacogenetically is azathioprine. The hematopoietic toxicity of azathioprine is due to single nucleotide polymorphisms in the thiopurine S-methyltransferase enzyme. Additionally, likely gene targets have been investigated to predict the response to glucocorticoids and infliximab, a monoclonal antibody against tumour necrosis factor that induces remission in approximately 30-40% of patients. However, no genetic predictor of response has been identified in either case.

Treatment of fistulizing Crohn's disease

The primary goals of the clinician in the treatment of fistulizing Crohn's disease (CD) include (1) defining the anatomy of the fistula, (2) draining any associated infectious material, (3) eradicating the fistulous tract through medical or surgical therapies, and (4) preventing recurrence of fistulas. Evaluation and therapeutic decisions require close collaboration between the gastroenterologist and surgeon. Appropriate evaluation should include identification of septic complications, delineation of the fistulous tract including the origin and terminus of the fistula, and determination of the extent of bowel involvement with active CD. Drainage of abscesses and control of septic complications through the placement of drains or setons is essential. Conservative therapy with avoidance of sphincter muscle-cutting procedures is the standard approach. The appropriate approach to asymptomatic patients is uncertain because there are little data to indicate if treatment alters the natural course of disease.

Medical management of the pregnant patient with inflammatory bowel disease

Gastroenterologists are not infrequently faced with questions regarding pregnancy when advising or treating their patients with inflammatory bowel disease (IBD). To advise patients effectively, the following factors must be considered: (1) the inheritance patterns of IBD for accurate counseling and family planning; (2) the effects of active IBD versus medications or surgery on fertility; (3) the effects of pregnancy on the course of IBD; (4) the effects and potential risks of active IBD versus those of diagnostic tests, medical treatments, and surgical treatments on the developing fetus; (5) approach to delivery; and (6) the risks of breast-feeding while receiving treatment for IBD.

Newer therapies for inflammatory bowel disease

Recent controlled and uncontrolled trial data in inflammatory bowel disease have suggested several new avenues of possible therapies and refined our understanding of the uses and selectiveness of anti-tumor necrosis factor (TNF)-based therapies. Infliximab remains the only proven effective anti-TNF therapy, whereas others have proven ineffective (etanercept, CDP-571) or of limited utility (thalidomide, CDP-870). A Crohn's disease Clinical trial Evaluating infliximab in a New long-term Treatment regimen (ACCENT I) and ACCENT II trials supported the strategy of using 5 to 10 mg/kg of infliximab on an every 8-week basis for maintenance of remission, although in clinical practice many physicians take variable approaches to maintenance of remission dosing schedules. On the other hand, no controlled trial data to date have supported the use of infliximab in ulcerative colitis. Therapies utilizing novel mechanistic approaches, such as hematopoietic growth factors, mitogen-activated protein (MAP)-kinase inhibition, and peroxisome proliferator activated receptor gamma ligand receptor binding have shown promise in small uncontrolled trials and await confirmation of their utility in randomized, placebo-controlled trials. Newer biologic (natalizumab) or cytokine-based therapies (monoclonal antibody to interleukin-6) have shown preliminary evidence of efficacy in controlled trials, but neither have yet been approved by the US Food and Drug Administration and, therefore, have not been commercialized. However, tacrolimus, a potent calcineurin inhibitor and inhibitor of interleukin-2 expression, has shown efficacy in Crohn's disease, albeit at the cost of substantial potential toxicity.

Refractory Inflammatory Bowel Disease

Therapeutic options for refractory colonic inflammation in patients with ulcerative colitis or Crohn's disease have recently been expanded with the introduction of biologic therapies. Intravenous corticosteroids and cyclosporine A remain the standard therapies for severe ulcerative colitis. Monoclonal antibodies directed at tumor necrosis factor-a have proven to be exceptionally efficacious in patients with severe or refractory Crohn's disease. Immunomodulatory therapy with azathioprine, 6-mercaptopurine, or methotrexate has demonstrated efficacy for maintenance of remission in patients with refractory ulcerative colitis or Crohn's disease. The use of experimental biologic agents may be considered for those patients who fail to respond to or remain dependent on corticosteroids. Surgical intervention still remains for patients with severe colitis who fail to respond to medical therapy or develop life-threatening complications such as perforation or toxic megacolon.

Crohn's disease: future anti-tumor necrosis factor therapies beyond infliximab

The dramatic benefit experienced by many Crohn's disease patients treated with the anti-tumor necrosis factor-alpha (TNF-alpha) antibody infliximab underscores the centrality of this cytokine in the pathogenesis of Crohn's disease and the potential use of the therapeutic strategy of blocking TNF-alpha in this disease. In the hopes of emulating and improving on the success of infliximab, numerous strategies are being devised and studied to inhibit the actions of TNF-alpha. This article focuses on those agents, other than infliximab, which target TNF-alpha to treat inflammatory bowel disease as their central mechanism of action.

Thalidomide

Despite its history as a human teratogen, thalidomide is emerging as a treatment for cancer and inflammatory diseases. Although the evolution of its clinical application could not have been predicted from the tragedy associated with its misuse in the past, its history serves as a lesson in drug development that underscores the need to understand the molecular pharmacology of a compound's activity, including associated toxicities. Here, we summarise the applications for thalidomide with an emphasis on clinical trials published over the past 10 years, and consider our knowledge of the molecular pharmacology of the drug in the context of clinical trial data, attempting to provide a mechanism-guided understanding of its activity.

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.

Review article: The medical treatment of Crohn's perianal fistulas

Perianal fistulas are a frequent manifestation of Crohn's disease. The correct application of the newer diagnostic and therapeutic agents for treating perianal Crohn's disease are beginning to be better defined. In general, a combined medical and surgical approach is preferred. The perianal disease process should first be fully delineated with endoscopy and either MRI or EUS before treatment is begun. Patients are then stratified into one of three groups: simple fistulas and no proctitis; simple fistulas and concomitant proctitis; and complex fistulas. Patients with simple fistulas and no proctitis can be treated medically with a combination of antibiotics and an immunosuppressive agent (azathioprine or mercaptopurine). Patients with simple fistulas and concomitant proctitis should have infliximab added to their treatment plan. Complex fistulas require surgical intervention first prior to medical treatment. A combination of antibiotics, immunosuppressive therapy and infliximab are then initiated to facilitate fistula healing.

Phase I study to determine the safety, tolerability and immunostimulatory activity of thalidomide analogue CC-5013 in patients with metastatic malignant melanoma and other advanced cancers

We assessed the safety, tolerability and efficacy of the immunomodulatory drug, CC-5013 (REVIMID™), in the treatment of patients with metastatic malignant melanoma and other advanced cancers. A total of 20 heavily pretreated patients received a dose-escalating regimen of oral CC-5013. Maximal tolerated dose, toxicity and clinical responses were evaluated and analysis of peripheral T-cell surface markers and serum for cytokines and proangiogenic factors were performed. CC-5013 was well tolerated. In all, 87% of adverse effects were classified as grade 1 or grade 2 according to Common Toxicity Criteria and there were no serious adverse events attributable to CC-5013 treatment. Six patients failed to complete the study, three because of disease progression, two withdrew consent and one was entered inappropriately and withdrawn from the study. The remaining 14 patients completed treatment without dose reduction, with one patient achieving partial remission. Evidence of T-cell activation was indicated by significantly increased serum levels of sIL-2 receptor, granulocyte–macrophage colony-stimulating factor, interleukin-12 (IL-12), tumour necrosis factor-α and IL-8 in nine patients from whom serum was available. However, levels of proangiogenic factors vascular endothelial growth factor and basic foetal growth factor were not consistently affected. This study demonstrates the safety, tolerability and suggests the clinical activity of CC-5013 in the treatment of refractory malignant melanoma. Furthermore, this is the first report demonstrating T-cell stimulatory activity of this class of compound in patients with advanced cancer.

Thalidomide Induces Apoptosis in Human Monocytes by Using a Cytochrome c-Dependent Pathway

Thalidomide has been shown to be an effective treatment in various immunologic diseases such as Crohn's disease and rheumatoid arthritis. Its major effect is thought to be mediated by the inhibition of TNF-alpha, but the exact mechanism of action is still uncertain. Recent observations could demonstrate that the induction of monocyte apoptosis is a common feature of a variety of anti-inflammatory agents. Therefore, we investigated the role of thalidomide on monocyte apoptosis. Treatment with thalidomide resulted in apoptosis of human peripheral blood monocytes in a time- and dose-dependent manner as demonstrated by annexin V staining. Monocyte apoptosis required the activation of caspases, as combined stimulation by thalidomide together with the broad caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone markedly prevented monocyte cell death. Apoptosis was triggered by a CD95/CD95 ligand, TNF-RI, and TRAIL-R1 independent pathway with an inhibition of AKT-1 kinase and consecutive mitochondrial release of cytochrome c, followed by the proteolytic activation of initiator caspase-9 and effector caspase-3. Our data suggest that thalidomide-induced monocyte apoptosis is at least partially mediated by a mitochondrial signaling pathway and might contribute to the complex immunomodulatory properties of the drug.

Maintenance of Remission in Crohn???s Disease

Crohn's disease is a chronic inflammatory bowel disorder with a relapsing and remitting course. Once remission is achieved, the main aim of the management of Crohn's disease is maintenance of that remission. Significant advances have been made into understanding the aetiology and pathogenesis of inflammatory bowel disease. With these advances in understanding come increasing numbers of new agents and therapies, aimed both at active disease and the subsequent maintenance of remission in Crohn's disease. Current therapeutic strategies in maintaining remission in Crohn's disease include 5-aminosalicylates (e.g. sulfasalazine, mesalazine), thiopurines (e.g. azathioprine, 6-mercaptopurine [mercaptopurine]), methotrexate and infliximab. The 5-aminosalicylates appear to have efficacy limited to either surgically induced remission and/or limited small bowel Crohn's disease. The immunomodulators now have an established role in Crohn's maintenance. Azathioprine and 6-mercaptopurine are effective in chronic active disease and corticosteroid-dependent Crohn's disease. Methotrexate has similar indications, although it appears to be an alternative in patients who are intolerant of, or resistant to, the thiopurines. The most recent breakthrough has been in the field of biological therapy for maintenance of remission in Crohn's disease. Treatment of patients with the anti-tumour necrosis factor (TNF)-alpha antibody infliximab has been shown already to be effective in inducing remission. Recent studies have now confirmed a role for infliximab in delaying relapse and maintaining remission in patients responsive to infliximab induction therapy. However, results with soluble TNF alpha receptors have been disappointing. A number of other biological and nonbiological agents have shown potential, though trials of the 'newer' biological agents have thus far been disappointing, in the maintenance of remission in Crohn's disease. The evidence for theses agents is currently limited, in many cases to treating active disease; however, these data are discussed in this article in order to provide an overview of future potential therapies. The aim of this review is to provide clinicians with an insight into current and emerging therapeutic agents for the maintenance of remission of Crohn's disease.

Clinical Pharmacokinetics of Thalidomide

Thalidomide is a racemic glutamic acid derivative approved in the US for erythema nodosum leprosum, a complication of leprosy. In addition, its use in various inflammatory and oncologic conditions is being investigated. Thalidomide interconverts between the (R)- and (S)-enantiomers in plasma, with protein binding of 55% and 65%, respectively. More than 90% of the absorbed drug is excreted in the urine and faeces within 48 hours. Thalidomide is minimally metabolised by the liver, but is spontaneously hydrolysed into numerous renally excreted products. After a single oral dose of thalidomide 200 mg (as the US-approved capsule formulation) in healthy volunteers, absorption is slow and extensive, resulting in a peak concentration (C(max)) of 1-2 mg/L at 3-4 hours after administration, absorption lag time of 30 minutes, total exposure (AUC( infinity )) of 18 mg. h/L, apparent elimination half-life of 6 hours and apparent systemic clearance of 10 L/h. Thalidomide pharmacokinetics are best described by a one-compartment model with first-order absorption and elimination. Because of the low solubility of the drug in the gastrointestinal tract, thalidomide exhibits absorption rate-limited pharmacokinetics (the 'flip-flop' phenomenon), with its elimination rate being faster than its absorption rate. The apparent elimination half-life of 6 hours therefore represents absorption, not elimination. The 'true' apparent volume of distribution was estimated to be 16L by use of the faster elimination-rate half-life. Multiple doses of thalidomide 200 mg/day over 21 days cause no change in the pharmacokinetics, with a steady-state C(max) (C(ss)(max)) of 1.2 mg/L. Simulation of 400 and 800 mg/day also shows no accumulation, with C(ss)(max) of 3.5 and 6.0 mg/L, respectively. Multiple-dose studies in cancer patients show pharmacokinetics comparable with those in healthy populations at similar dosages. Thalidomide exhibits a dose-proportional increase in AUC at doses from 50 to 400 mg. Because of the low solubility of thalidomide, C(max) is less than proportional to dose, and t(max) is prolonged with increasing dose. Age, sex and smoking have no effect on the pharmacokinetics of thalidomide, and the effect of food is minimal. Thalidomide does not alter the pharmacokinetics of oral contraceptives, and is also unlikely to interact with warfarin and grapefruit juice. Since thalidomide is mainly hydrolysed and passively excreted, its pharmacokinetics are not expected to change in patients with impaired liver or kidney function.

Medical management of Crohn's disease

Current evidence strongly suggests that Crohn's disease is caused by an abnormal response to enteric flora. This review examines the current evidence for medical management of Crohn's disease, particularly focusing on alternative therapies to corticosteroids in managing disease relapses and preventing long-term complications.

Biological therapy in Crohn's disease

The discovery of the central role of tumour necrosis factor-alpha in Crohn's disease and the subsequent introduction of infliximab into routine clinical practice has transformed the treatment of refractory disease. Advances in understanding of the immunopathological basis of Crohn's disease are leading to the development of new biological therapies which are likely to play an increasing role in future.

Treatment of Fistulizing Crohn's Disease in Children

Patients with Crohn's disease are at risk for developing both internal and external fistulae. These can be asymptomatic incidental radiologic findings or causes of incontinence, chronic pain, abscesses, and sepsis. They can have a devastating impact on quality of life. Careful prospective studies of therapy are few in adult medicine and entirely lacking in the pediatric age group. Assessment and management require a coordinated effort between gastroenterologist, radiologist, and surgeon. Principles of management include surgical drainage of infection combined with medical therapy. Only infliximab has been studied in prospective, double-blinded fashion and clearly shown to be of use in the short term. There is good evidence that metronidazole may be useful acutely and that 6-mercaptopurine azathioprine may help to maintain closure. Diverting ostomies are of very limited value and corticosteroids seem to make matters worse. There are many other therapies that have been reported to be helpful in small, uncontrolled studies.

Comparison between methotrexate and azathioprine in the treatment of chronic active Crohn's disease: a randomised, investigator-blind study

BACKGROUND AND AIMS

The efficacy of azathioprine in the treatment of chronic active Crohn's disease is well established. However, this drug has a long onset of action. Methotrexate has also been shown to be effective in chronic active Crohn's disease. The aim of this study was to evaluate the efficacy and safety of methotrexate in comparison with azathioprine, and to establish whether methotrexate has a shorter onset of action in this setting.

METHODS

Patients with chronic active Crohn's disease were admitted to this investigator-blind study. Chronicity was defined as the need for steroid therapy of > or = 10 mg/day for at least 4 months during the preceding 12 months, with at least one attempt to discontinue treatment. The disease had to be clinically active at entry, with a Crohn's Disease Activity Index of > or = 200. Six patients treated with azathioprine and methotrexate, respectively, were found to have enterocutaneous and perianal fistulas. At entry, all patients received prednisolone (40 mg once a day) which was tapered over a period of 12 weeks unless their clinical condition deteriorated. All patients were randomised to receive i.v. methotrexate 25 mg/week, or oral azathioprine 2 mg/kg per day, for a 6-month follow-up period. After the first 3 months, methotrexate was switched to oral administration maintaining the same dose. The primary efficacy outcome considered was the proportion of patients entering first remission after 3 and 6 months of therapy. Clinical remission was defined as the lack of need for steroid treatment and a Crohn's Disease Activity Index score of < or = 150 points at each scheduled visit.

RESULTS

In the 54 patients (26 F, 28 M, mean age 34 years, range 18-60) randomly assigned to methotrexate (n=27) or azathioprine (n=27), no statistically significant difference was found between the two treatment regimens with respect to remission rate after 3 (methotrexate 44%, azathioprine 33%, p=0.28, (95% CI, 0.369-0.147), and 6 months (methotrexate 56%, azathioprine 63%, p=0.39, 95% CI, 0.187-0.335), respectively. Six patients withdrew from therapy due to adverse events: 3/27 (11%) in methotrexate and 3/27 (11%) in azathioprine. Drug-related adverse events (asthenia, nausea and vomiting) that did not require withdrawal from therapy were more frequent in the methotrexate group (azathioprine: 2/27 (7%); methotrexate: 12/27 (44%), p=0.00009). The frequency of these adverse events was comparable during the intravenous or oral administration of the drug.

CONCLUSIONS

This study confirms that methotrexate is effective in inducing remission in patients with chronic active Crohn's disease, therapeutic efficacy being comparable, but not faster, than that of azathioprine.

Dietary glycine prevents chemical-induced experimental colitis in the rat

BACKGROUND & AIMS

In this study, the effect of dietary glycine on experimental colitis induced by 2,4,6-trinitrobenzene sulphonic acid (TNBS) and dextran sulfate sodium (DSS) in the rat was evaluated.

METHODS

Male Wistar rats were fed a diet containing 5% glycine or casein as controls starting 3 days before experiments, and were given a single intracolonic injection of TNBS (50 mg/rat, dissolved in 50% ethanol). Similarly, some rats were given 3% DSS orally in drinking water for 5 days to induce colitis as a second model. The severity of colitis was evaluated pathologically, and tissue myeloperoxidase (MPO) activity was measured. Further, mRNA and protein levels for interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, cytokine-induced neutrophil chemoattractant (CINC), and macrophage inflammatory protein (MIP)-2 were detected by reverse-transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively.

RESULTS

A diet containing glycine ameliorated diarrhea and body weight loss caused by TNBS, and improved both macroscopic and histologic scores of colitis significantly. TNBS-induced increases in MPO activities in the colonic tissue were blunted significantly in glycine-fed animals. Further, dietary glycine largely prevented increases in IL-1beta and TNF-alpha in the colon 2 days after TNBS, and TNBS induction of CINC and MIP-2 in the colonic tissue also was abrogated by glycine. Importantly, the protective effect of glycine was significant even when TNBS colitis was once established. Moreover, dietary glycine also was preventive in a second, DSS-induced colitis model.

CONCLUSIONS

Dietary glycine prevents chemical-induced colitis by inhibiting induction of inflammatory cytokines and chemokines. It is postulated that glycine may be useful for the treatment of inflammatory bowel diseases as an immunomodulating nutrient.

Protective effect of thalidomide on endotoxin-induced liver injury

BACKGROUND

Activation of Kupffer cells by lipopolysaccharide (LPS) plays a pivotal role in the onset of pathophysiological events that occur during endotoxemia, and intracellular calcium concentration ([Ca2+]i) is involved in LPS-stimulated cytokine production. Tumor necrosis factor (TNF)-alpha is produced exclusively by the monocyte-macrophage lineage, which is mostly made up of Kupffer cells, and thalidomide has been shown to reduce TNF-alpha production from macrophages. However, there is increasing evidence that TNF-alpha may play a role in the initiation or progression of multiple organ failure syndrome. Therefore, the purpose of this work was to determine whether thalidomide could prevent LPS-induced liver injury.

METHODS

Rats were given a single oral dose of thalidomide (5 mg/kg). To assess the sensitization of Kupffer cells, LPS (5 or 10 mg/kg) was administered intravenously, and mortality, liver histology, and transaminases were evaluated 24 hr later. Kupffer cells were isolated 2 hr after thalidomide treatment. After the addition of LPS, [Ca2+]i was measured by using a microspectrofluorometer with the fluorescent indicator fura-2, and TNF-alpha was measured by enzyme-linked immunosorbent assay.

RESULTS

LPS caused focal necrosis with neutrophil infiltration in the liver. Moreover, LPS dramatically increased transaminases. These pathologic parameters and increases of serum transaminases were diminished markedly by thalidomide. In isolated Kupffer cells, LPS-induced increases in [Ca2+]i and TNF-alpha production were suppressed by treatment with thalidomide. To further explore the mechanism by which thalidomide directly abrogated Kupffer cell sensitivity to LPS, we determined the effect of thalidomide (5 microM) in vitro on LPS-induced [Ca2+]i response and TNF-alpha production. With the addition of thalidomide (5 microM) in vitro to the culture media for 2 hr before LPS, these parameters were suppressed.

CONCLUSIONS

Thalidomide prevents LPS-induced liver injury via mechanisms dependent on the suppression of TNF-alpha production from Kupffer cells.

Targeting tumor necrosis factor-alpha in inflammatory bowel disease: why, how, and when?

A large proportion of patients with inflammatory bowel disease require more effective therapy, especially for the prevention of disease relapse. Recent therapeutic advances have focused on biologicals (monoclonal antibodies, therapeutic peptides, antisense oligonucleotides) that aim to neutralize specific proinflammatory proteins. This has proved successful for the anti-TNF-alpha antibody infliximab in patients with Crohn disease, but recent studies failed to demonstrate the efficacy of different anti-TNF-alpha strategies. Therefore, it seems essential to fully comprehend the molecular mechanisms of such compounds. An exciting development has been the association between drug efficacy and the induction of apoptosis in apoptosis-resistant lamina propria T cells in Crohn disease. Furthermore, TNF-alpha can also be targeted by "small molecules" to circumvent certain disadvantages of biologicals such as the nonoral route of administration, the potential immunogenicity, and the high costs of treatment. Several of these developments will certainly be relevant for designing future anti-TNF-alpha based strategies.

Review article: medical treatment of moderate to severe Crohn's disease

The treatment for patients with Crohn's disease of moderate to severe activity includes traditional drugs, such as corticosteroids, the primary therapy for these forms of disease, able to induce the remission of symptoms in a high percentage of patients. Because of the side-effects produced by systemic steroids, a new glucocorticoid derivative, budesonide, which acts locally in the mucosa, has recently been introduced with positive results. On the assumption that intestinal bacteria play a role in the causing Crohn's disease symptoms, antibiotics are often used in the treatment of active phases, as an alternative to or in association with steroids. The most widely employed antibiotics are metronidazole and ciprofloxacin. Immunosuppressors, such as azathioprine and 6-mercaptopurine, are useful for the treatment of chronic active disease and for maintaining remission, but they have only a marginal role in the therapy of an acute flare-up of Crohn's disease. Methotrexate acts more rapidly and its use in patients with active disease resistant to standard therapy is of interest. The discovery of biological agents represents a new era in the management of patients. To date, infliximab is the more extensively studied biological therapy in the treatment of Crohn's disease and clinical studies have demonstrated its efficacy in inducing remission of refractory disease.

Connections between psoriasis and Crohn's disease

The prevalence of psoriasis in patients with Crohn's disease (CD) is higher than chance would allow if they were mutually exclusive diseases. A close examination reveals genetic and pathologic connections between these diseases. An appreciation for the role of tumor necrosis factor-alpha in both diseases has proven very important. Increased levels of this inflammatory cytokine have been measured in CD lesions, and in 1997 a clinical trial demonstrated the response of this disease to infliximab, a monoclonal antibody specific for tumor necrosis factor-alpha. A subsequent clinical trial evaluated infliximab in a patient with CD and psoriasis, another disease in which increased levels of tumor necrosis factor-alpha are seen in lesions. Scientists noticed the marked skin improvement of this patient and later demonstrated the efficacy of infliximab for psoriasis in a randomized, double-blind, placebo-controlled trial. Thus, an appreciation for connections between psoriasis and CD can suggest novel therapeutic strategies with ensuing benefits to patients. This article reviews epidemiologic, genetic, and pathologic connections between psoriasis and CD and discusses pharmaceuticals targeting inflammatory mediators common to each disease. (J Am Acad Dermatol 2003;48:805-21.)

LEARNING OBJECTIVE

At the completion of this learning activity, participants should understand how psoriasis and Crohn's disease are related at epidemiologic, genetic, and pathological levels and should appreciate how to use this knowledge to treat these diseases.

Pharmacogenomics of response to anti-tumor necrosis factor therapy in patients with Crohn's disease

The relatively recent development of genetically engineered agents has the potential to alter the treatment of Crohn's disease radically, and drugs that inhibit tumor necrosis factor-alpha (TNFalpha) have been introduced as a new therapeutic class with high efficacy, rapid onset of action, prolonged effect, and improved tolerance. However these agents are expensive and at least one-third of the eligible patients fail to show any useful response. Finding a means to predict those who will respond, and to anticipate relapse are, therefore, of obvious importance. T helper-type 1 (Th1) lymphocytes orchestrate much of the inflammation in Crohn's disease mainly via production of TNFalpha, which appears to play a pivotal role as a pro-inflammatory cytokine. It exerts its effects through its own family of receptors (TNFR1 and TNFR2), the end results of which include apoptosis, c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) activation and NF-kappaB activation. Activated NF-kappaB enters the nucleus and induces transcription of genes associated with inflammation, host defense and cell survival. The promoter region of the TNF gene lies between nucleotides -1 and -1300, and encompasses numerous polymorphic sites associated with potential binding sites for various transcription factors. Carriers of the TNF allele 2 (TNF2), which contains a single base-pair polymorphism at the -308 promoter position, produce slightly more TNFalpha in their intestinal mucosa than non-TNF2 carriers. TNF polymorphisms also appear to influence the nature and frequency of extraintestinal manifestations of inflammatory bowel disease (IBD). A number of routes of inhibition of TNF are being investigated. Most extensively evaluated is the use of monoclonal antibodies against TNFalpha (e.g. infliximab). Several large controlled trials indicate that infliximab has a role in treating patients with moderate to severely active Crohn's disease and in fistulating Crohn's disease. Although it would be useful to genetically differentiate 'responders' from 'non-responders,' currently there are few published data on TNF polymorphisms in IBD, and often only selected polymorphisms are genotyped. Small studies have shown possible associations between poor response to infliximab and increasing mucosal levels of activated NF-kappaB, homozygosity for the polymorphism in exon 6 of TNFR2 (genotype Arg196Arg), positivity for perinuclear antineutrophil cytoplasmic antibodies (ANCA), and with the presence of increased numbers of activated lamina propia mononuclear cells producing interferon-gamma and TNFalpha. This is a rapidly changing field, and more information of greater direct clinical benefit can be expected soon.

Thalidomide for the treatment of recalcitrant oral Crohn's disease and orofacial granulomatosis

It has been suggested that thalidomide may be effective in the management of Crohn's disease, including the associated oral lesions. We detail the clinical response to low-dose thalidomide of 5 patients with clinical features of orofacial granulomatosis or oral Crohn's disease recalcitrant to recognized immunosuppressant therapy. All patients had clinical resolution of their symptoms and signs. Transient somnolence was the only reported adverse effect. Remission was maintained by extending the period between thalidomide doses. Thalidomide should be considered an effective therapy for the short-term treatment of severe orofacial granulomatosis in appropriately counseled patients.

Thalidomide and its derivatives: emerging from the wilderness

Forty years on from its worldwide withdrawal, thalidomide is currently undergoing a remarkable renaissance as a novel and powerful immunomodulatory agent. Over the last decade it has been found to be active in a wide variety of inflammatory and malignant disorders where conventional therapies have failed. Recently, considerable progress has been made in elucidating its complex mechanisms of action, which include both anticytokine and antiangiogenic properties. However, in addition to its well known teratogenic potential, it has a significant side effect profile that leads to cessation of treatment in up to 30% of subjects. In response to this, two new classes of potentially safer and non-teratogenic derivatives have recently been developed. This review summarises the biological effects, therapeutic applications, safety profile, and future potential of thalidomide and its derivatives.

Inflammatory bowel disease in pregnancy

Fertility is affected in ulcerative colitis after surgery and in active Crohn's disease. Adverse fetal outcomes are not increased when IBD is quiescent. Active disease at conception increases the risk of adverse fetal outcomes. Most medications for IBD are safe during pregnancy and breastfeeding, with notable exceptions. Active disease is usually more deleterious than maintaining medical therapy.

Strategies for targeting tumour necrosis factor in IBD

Tumour necrosis factor (TNF) plays an important role in mediating the inflammation of inflammatory bowel disease, in particular, Crohn's disease. Strategies aimed at reducing tumour necrosis factor in patients with inflammatory bowel disease include the mouse/human chimeric monoclonal antibody infliximab, the humanized monoclonal antibody CDP571, the human soluble TNF p55 receptor onercept, the human monoclonal antibody D2E7 (adalimumab), the anti-TNF human antibody Fab' fragment-polyethelene glycol (PEG) conjugate CDP870, and the small molecules thalidomide and CNI-1493 (MAP-kinase inhibitor). Infliximab is effective for treating active Crohn's disease, maintaining remission, closing fistulas, maintaining fistula closure, and treating ankylosing spondylitis. Infliximab is also being investigated for the treatment of ulcerative colitis. Side-effects occurring in patients treated with infliximab include human anti-chimeric antibodies, infusion reactions, delayed hypersensitivity reactions, formation of autoantibodies, and, in rare circumstances, drug-induced lupus and serious infections, including tuberculosis. CDP571 is effective for treating active Crohn's disease, steroid sparing, and possibly for closing fistulas and maintaining remission. Side-effects occurring in patients treated with CDP571 include anti-idiotype antibodies, infusion reactions and the formation of autoantibodies. A controlled trial of etanercept in patients with Crohn's disease was negative. Pilot studies with onercept, thalidomide, and CNI-1493 have suggested benefit for Crohn's disease. There are no published data on the efficacy of adalimumab (D2E7) or CDP870 for either Crohn's disease or ulcerative colitis. Anti-tumour necrosis factor therapies are effective for the treatment of Crohn's disease and are being investigated for ulcerative colitis.

Thalidomide: a review of approved and investigational uses

BACKGROUND

Thalidomide is best known as a major teratogen that caused birth defects in up to 12,000 children in the 1960s. More recently, this agent has been approved by the US Food and Drug Administration for the treatment of erythema nodosum leprosum (ENL) through a restricted-use program. Its immunomodulatory, anti-inflammatory, and antiangiogenic properties are currently under study in a number of clinical conditions.

OBJECTIVE

This article reviews the pharmacology of thalidomide; its approved and off-label uses in dermatologic, oncologic, and gastrointestinal conditions; and adverse events associated with its use.

METHODS

Relevant articles were identified through searches of MEDLINE (1966-June 2002), International Pharmaceutical Abstracts (1970-June 2002), and EMBASE (1990-June 2002). Search terms included but were not limited to thalidomide, pharmacokinetics, pharmacology, therapeutic use, and teratogenicity, as well as terms for specific disease states and adverse events. Further publications were identified from the reference lists of the reviewed articles. Abstracts of recent symposia were obtained from the American Society of Clinical Oncology Web site.

RESULTS

Thalidomide is thought to exert its therapeutic effect through the modulation of cytokines, particularly tumor necrosis factor-alpha. In addition to its approved indication for ENL, thalidomide has been studied in various other conditions, including graft-versus-host disease, discoid lupus erythematosus, sarcoidosis, relapsed/refractory multiple myeloma, Waldenstrom's macroglobulinemia, myelodysplastic syndromes, acute myeloid leukemia, myelofibrosis with myeloid metaplasia, renal cell carcinoma, malignant gliomas, prostate cancer, Kaposi's sarcoma, colorectal carcinoma, oral aphthous ulcers, Behçet's disease, Crohn's disease, and HIV/AIDS-associated wasting. Adverse events most frequently associated with its use include somnolence, constipation, rash, peripheral neuropathy, and thromboembolism.

CONCLUSIONS

Use of thalidomide is limited by toxicity, limited efficacy data, and restricted access. Evidence of its efficacy in conditions other than ENL awaits the results of controlled clinical trials.

Azathioprine and anti-TNF alpha therapies in Crohn's disease: a review of pharmacology, clinical efficacy and safety

Crohn's disease (CD), a chronic relapsing inflammatory condition of the intestines, is a common cause of gastrointestinal morbidity in young people. Although the aetiology of CD is unknown, host, genetic and environmental influences are clearly important. Glucocorticoids remain the mainstay of treatment for active CD, however only two-third of patients will respond and side effects are considerable. Surgery is often undesirable or impracticable and therefore alternative medical strategies have been sought. In recent years, there has been much interest in two areas of IBD therapy-the use of established immunomodulators, and the development of novel biological therapies. In this review, we have selected two areas of particular controversy-the use of purine analogues (azathioprine (AZA) and 6-mercaptopurine (6-MP)) and the introduction of anti-tumour necrosis factor alpha (TNFalpha) therapy and have examined the data for efficacy, safety and tolerability of these medications.

A pilot study of thalidomide for patients with symptomatic mesenteric panniculitis

BACKGROUND

Mesenteric panniculitis is a rare condition with no standard therapy.

AIM

To assess the safety and efficacy of thalidomide for the treatment of patients with symptomatic mesenteric panniculitis using a newly established clinical disease activity index (Mesenteric Panniculitis Subjective Assessment Score).

METHODS

In an open-label pilot study, five patients with symptomatic mesenteric panniculitis received oral thalidomide, 200 mg nightly, for 12 weeks. The primary end-point was a reduction in the Mesenteric Panniculitis Subjective Assessment Score by > or = 20% at 12 weeks or complete remission (absence of symptoms).

RESULTS

Four (80%) of the five patients responded. The median Mesenteric Panniculitis Subjective Assessment Score at baseline was 39 and at week 12 was 25 (average decrease of 44%). One patient achieved complete remission by week 4, which was sustained. At 12 weeks, three (75%) patients experienced a global response, five (100%) patients had a > or = 20% (range, 29-98%) decrease in erythrocyte sedimentation rate and three (75%) patients had a > or = 20% (range, 61-93%) decrease in C-reactive protein. Abdomino-pelvic computed tomography scans were unchanged in all five patients. There were no serious adverse events.

CONCLUSIONS

Thalidomide is safe, well tolerated and efficacious in the treatment of some patients with symptomatic mesenteric panniculitis. Further study is indicated.

Advances in medical therapy for Crohn's disease

Management of Crohn's disease has changed considerably in recent years. The discovery of tumor necrosis factor (TNF) as a pivotal cytokine in the inflammatory cascade has led to the development of several neutralizing antibodies, soluble receptors, and small molecules, interfering with TNF gene transcription and expression. Infliximab is the only monoclonal antibody that is commercially available. This potent molecule is effective for both active and fistulizing disease in the acute and maintenance phases of treatment. In addition to anti-TNF agents, weekly methotrexate injection and the classic "antimetabolites" azathioprine and 6-mercaptopurine remain highly valuable as maintenance drugs. "Tailored" antimetabolite therapy has now become possible with metabolite measurements and determination of the TPMT gene. The active metabolite thioguanine itself could be a promising alternative in patients who are intolerant of 6-mercaptopurine. In fistulizing disease, infliximab is becoming the treatment of choice, although fistula tracks do not disappear permanently and many patients still need surgical intervention.

Inflammatory bowel disease: new insights into pathogenesis and treatment

Despite all the advances in our understanding of the pathophysiology of inflammatory bowel disease (IBD), we do not know the cause. Some of the most recently available data have been discussed here and yet it is now becoming increasingly accepted that immunogenetics play an important role in the predisposition, modulation, and perpetuation of IBD. The mucosal immune system is the central effector of intestinal inflammation and injury, with cytokines playing a central role in modulating inflammation. The role of intestinal milium, and enteric flora in particular, appears to be of greater significance than previously held. A review is made of the main areas of research exploring the mechanisms more intimately associated with the development of IBD, providing advances in the agents currently used, and identifying a host of new therapeutic agents potentially interacting with or interrupting specific targets in the genesis of IBD.

Recent developments in inflammatory bowel disease

The evolving medical armamentarium holds promise for more precise and effective therapies for IBD. The experience with anti-TNF therapy, particularly infliximab, illustrates the potential efficacy of therapies targeted at specific mediators or pathways involved in the pathogenesis. Advances in molecular technology have enabled the development of novel and potentially effective targeted therapies. Equally important is the increasing scientific understanding of the pathogenesis of IBD, which will likely improve the ability to stratify disease and to select therapies based on genotypic, immunologic, and phenotypic profiles in the future.

Antitumour necrosis factor therapy in Crohn's disease

The key role and contribution of various pro-inflammatory cytokines in common chronic inflammatory disorders such as inflammatory bowel disease (IBD) has been thoroughly investigated in recent years. Besides IL-1, TNF-alpha has been identified as one of the central immune mediators controlling inflammatory processes. Not surprisingly, neutralisation of these cytokines has been introduced into clinical research. Crohn's disease (CD) is one of the chronic inflammatory disorders where TNF-alpha seems to have a particularly important role. Neutralisation of this cytokine by specific antibodies, for example infliximab, has been shown recently to affect the clinical phenotype of this disorder. Other TNF-neutralising approaches such as etanercept have also been studied in patients with CD but with less successful outcomes. These new cytokine-targeting approaches have changed clinical medicine in the field of inflammatory disorders.

Thalidomide as "salvage" therapy for patients with delayed hypersensitivity response to infliximab: a case series

Infliximab is efficacious for refractory Crohn's disease, but delayed hypersensitivity reactions preclude retreatment for patients experiencing this complication. We report the results of four patients offered enrollment in an open label trial of thalidomide as "salvage" therapy for their refractory disease. Two patients with active fistulous disease and two with lumenal disease received open-label thalidomide 200 mg every night and were evaluated monthly at the University of Chicago Clinical Research Center for 12 weeks. Before administration, patients signed an informed consent form discussing the potential risks of thalidomide use. Female patients of child-bearing age underwent serum pregnancy testing every 4 weeks. Response was defined as an absolute decrease in Crohn's Disease Activity Index (CDAI) by 100 points or improvement in two of three clinical parameters for fistulous disease. A patient with a single perirectal fistula had complete closure by 4 weeks, the other had noticeable improvement of five perianal fistulae at 4 weeks and complete closure by 12 weeks. One lumenal patient had a CDAI decrease of 250 points in 4 weeks. The fourth patient withdrew secondary to sedation after only a week of therapy. Two patients (one fistula, one lumenal) continued thalidomide past the 3-month study period and remained in remission at 5 and 7 months. Side effects reported were sedation (four of four patients), hypertension (one of four), and peripheral neuropathy (one of four). Thalidomide appears to be a safe and effective alternative for short-term healing in patients who develop infliximab-induced delayed hypersensitivity reaction and may be an alternative strategy for those at risk.

Advances in the medical therapy of inflammatory bowel disease

The medical therapy of inflammatory bowel disease (IBD) has advanced significantly over the past year. Serologic markers of IBD have been further investigated and better defined, showing some discriminatory power with potential therapeutic implications. Studies of azathioprine and 6-mercaptopurine metabolites will make it easier and safer to use these effective drugs. Clinical data using other immunomodulators, including 6-thioguanine, mycophenolate mofetil, cyclosporine, and tacrolimus, continue to accrue with positive results. Infliximab has become even more firmly established as a reliable and effective therapy for active and fistulizing Crohn disease and may even be helpful in some patients with resistant ulcerative colitis. However, the recognition of potential complications of infliximab therapy has increased with the accumulated clinical experience. Results from trials of other biologic therapies directed at tumor necrosis factor alpha have been disappointing so far, although preliminary studies with biologics directed at adhesion molecules are encouraging. Growing appreciation of the importance of the enteric microflora in IBD has led to a considerable interest in manipulating intestinal bacteria for therapeutic benefit, and trials of both probiotics and prebiotics show promise.

[Interest in thalidomide in cutaneo-mucous and hypothalamo-hypophyseal involvement of Langerhans cell histiocytosis]

INTRODUCTION

Histiocytosis X or Langerhans cell granuloma is a rare disease characterised by the proliferation of phagocytes which have normal cell markers.

EXEGESIS

We report the case of a 44-year old woman with hypothalamo-hypophyseal Langerhans cell histiocytosis with genital and oral cutaneo-mucous involvements. After several non-active treatments, thalidomide began. Oral and genital lesions healed quickly. Recurrence of symptoms was observed six months after the treatment was stopped and a complete remission was obtained when thalidomide was reintroduced. The regression of hypothalam-hypophyseal granuloma infiltration was confirmed by MRI and the treatment was well tolerated by the patient.

CONCLUSION

Cutaneo-mucous Langerhans cell disease as well as hypothalamo-hypophyseal histiocytosis may both benefit from a treatment with thalidomide.

Thalidomide prevents alcoholic liver injury in rats through suppression of Kupffer cell sensitization and TNF-alpha production

BACKGROUND & AIMS

Sensitization of Kupffer cells (KCs) to lipopolysaccharide (LPS) and overproduction of tumor necrosis factor (TNF) alpha are critical for progression of alcoholic liver injury. Thalidomide has been shown to suppress TNF-alpha production from macrophages. Accordingly, the purpose of this study was to determine whether thalidomide could prevent alcohol-induced liver injury.

METHODS

Rats were given ethanol (5 g/kg body wt) and thalidomide (5 mg/kg) once every 24 hours intragastrically. To assess the sensitization of Kupffer cells, LPS (5 mg/kg intravenously) was administered and liver histology was evaluated 24 hours later. KCs were isolated after 4 weeks of ethanol treatment and intracellular Ca2+ ([Ca2+]i) was measured using fura-2, whereas TNF-alpha was evaluated by reverse-transcription polymerase chain reaction and enzyme-linked immunosorbent assay. CD14 was determined by Western and fluorescence staining.

RESULTS

Treatment with ethanol for 8 weeks caused marked steatosis, necrosis, and inflammation in the liver. These pathologic parameters were diminished markedly by treatment with thalidomide. In the 4-week ethanol group, the LPS-induced liver damage was aggravated and KCs were sensitized to LPS. Coadministration of thalidomide with ethanol prevented the KC sensitization completely. Furthermore, thalidomide abolished the LPS-induced increase in CD14 expression and [Ca2+]i elevation in KCs. Gut permeability was increased about 10-fold after 4 weeks of ethanol exposure, which was not affected by thalidomide. Moreover, thalidomide reduced the LPS-induced TNF-alpha production by KCs by decreasing TNF-alpha messenger RNA.

CONCLUSIONS

These results collectively indicate that thalidomide prevents alcoholic liver injury through suppression of TNF-alpha production and abolishment of KC sensitization.

Therapy of Crohn's disease in childhood

Crohn's disease in childhood is a chronic relapsing and remitting condition that can significantly impact on normal growth and development. This influences the choice of both initial and ongoing management. The goal of therapy is to induce and maintain remission with minimal side effects. Enteral nutrition as the sole therapy for active disease is effective in some children, thus avoiding the use of corticosteroids. In disease that is resistant to conventional treatment, immunosuppression or anti-tumour necrosis factor therapy is indicated. We review the use of these treatments and discuss the new therapies being developed, including antibodies, cytokines and probiotics.

Inflammatory Bowel Disease in Children

Crohn's disease and ulcerative colitis remain medically incurable conditions with potentially significant morbidity. The treatment of children with these conditions therefore should seek to reduce or eliminate symptoms, optimize nutritional status, promote normal growth and development, prevent complications, and minimize the potential psychologic effects of chronic illness. Treatment strategies must seek to both induce and maintain clinical remission. For all but the most mildly affected children with Crohn's disease, a combination of nutritional and pharmacologic approaches is optimal. For those with ulcerative colitis, anti-inflammatory medication is necessary. Moderate to severe Crohn's disease acutely responds best to potent immunomodulatory therapy, eg, corticosteroids and infliximab. Either agent must be coupled with 6-mercaptopurine or azathioprine to maintain long-term remission and to minimize toxicity. Particular attention must be paid to limit the growth suppression and other toxic effects of corticosteroids. Elemental or semielemental enteral nutrition also can induce remission effectively, but relapse is common after primary nutritional therapy is discontinued, mandating concomitant pharmacologic therapy with either 6-mercaptopurine or azathioprine. The availability of 6-mercaptopurine/azathioprine metabolite testing allows optimization of immunomodulatory therapy, detection of noncompliance, and avoidance of potentially dangerous toxicity. Mild ulcerative colitis acutely responds to treatment with a 5-aminosalicylate medication. Long-term remission frequently can be maintained with the same medication. Moderate to severe disease activity requires potent immunomodulatory therapy if colectomy is to be avoided. Surgery is a potential cure for patients with ulcerative colitis, although the development of pouchitis after ileal pouch anal anastomosis is common and frequently requires long-term medical management. Surgery provides only palliative relief of complications in those with Crohn's disease. Emerging therapies, especially evolving biologic and probiotic agents, offer hope for better treatments in the years ahead.

An open-label study of thalidomide for maintenance therapy in responders to infliximab in chronically active and fistulizing refractory Crohn's disease

BACKGROUND

Infliximab, a chimeric monoclonal antibody to tumour necrosis factor-alpha, is a new potent therapy for active Crohn's disease, but induces short-lived improvements.

AIM

To evaluate the efficacy of thalidomide, a drug with anti-tumour necrosis factor-alpha activity, for the maintenance of infliximab-induced response in refractory Crohn's disease.

METHODS

Fifteen patients with severe, refractory disease (10 females, five males; mean age, 40 years; eight with luminal disease, two with fistulizing disease and five with both luminal and fistulizing disease) were started on thalidomide (100 mg daily), 29 +/- 10 days after they had responded to infliximab (5 mg/kg infusions).

RESULTS

The median follow-up period was 238 days (range, 10-458 days) from the initiation of thalidomide and 265 days (range, 10-537 days) from the last infliximab infusion. The median Crohn's disease activity indices were 322 (range, 170-525), 119 (range, 24-503) and 35 (range, -60-360) before infliximab, at the initiation of thalidomide and at the end of follow-up, respectively. Remission rates on thalidomide were 92%, 83% and 83% at 3, 6 and 12 months, respectively, after the last infliximab infusion (Kaplan-Meier). Four patients (two in remission) stopped thalidomide for suspected adverse effects. Side-effects (drowsiness, rash and peripheral neuropathy) were mild and mostly transient.

CONCLUSIONS

Thalidomide appears to be an effective and relatively safe drug to maintain response to infliximab in chronically active and fistulizing refractory 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.