Infliximab but not etanercept induces apoptosis in lamina propria T-lymphocytes from patients with Crohn's disease

Safety of Tumour Necrosis Factor-?? Antagonists

Tumour necrosis factor-alpha (TNFalpha) is a proinflammatory cytokine that is synthesised by a variety of cell types in response to infectious or inflammatory stimuli. Although TNFalpha plays an adaptive role in immune protection and wound healing at 'physiological' levels, excess TNFalpha production can lead to adverse consequences. TNFalpha is a pivotal cytokine involved in the pathogenesis and progression of rheumatoid arthritis (RA). TNFalpha antagonists have been shown to be effective in the treatment of signs and symptoms of RA and the US FDA has approved three TNFalpha antagonists, etanercept, infliximab, and most recently, adalimumab, for the treatment of RA. However, differences have emerged, with respect to their demonstrated efficacy in other diseases (e.g. Crohn's disease). Worldwide, over half a million patients have been treated with TNFalpha antagonists and concerns regarding their safety have been raised. There is a risk of reactivation of granulomatous diseases, especially tuberculosis, with all three agents and appropriate measures should be taken for detection and treatment of latent infections. An association between non-Hodgkin's lymphoma and treatment with TNFalpha antagonists has been reported, although patients with active, long-standing RA are already known to have an increased incidence of non-Hodgkin's lymphoma. No associations with solid tumours have been found to date. The biological plausibility of lymphomas associated with immunomodulatory agents raises concern and vigilance is appropriate until the relationship is fully characterised. Large phase II and III trials have shown a detrimental effect of TNFalpha antagonists in advanced heart failure and these agents should be avoided in this population. Rare case reports of drug-induced lupus, seizure disorder, pancytopenia and demyelinating diseases have been noted after TNFalpha antagonists and continued vigilance is warranted in patients on TNFalpha antagonists for the development of these diseases. At present there is no evidence implicating TNFalpha antagonists with embryotoxicity, teratogenicity or increased pregnancy loss.

Optimizing anti-tumor necrosis factor strategies in inflammatory bowel disease

The introduction of infliximab, a mouse/human chimeric monoclonal antibody to tumor necrosis factor (TNF), is an important advance in the treatment of Crohn's disease. Infliximab is effective for induction and maintenance of remission in patients with inflammatory luminal and fistulizing disease. The development of human antichimeric antibodies (HACAs) has led to infusion reactions and loss of efficacy in patients treated with infliximab. Strategies to reduce the frequency of HACA formation include induction of immunologic tolerance with a three-dose regimen at 0, 2, and 6 weeks followed by systematic maintenance dosing every 8 weeks; concomitant immunosuppressive therapy with azathioprine, 6-mercaptopurine, or methotrexate; and premedication with intravenous corticosteroids. Humanized or fully human anti-TNF biotechnologic agents, including CDP571, CDP870, etanercept, adalimumab, and onercept, are theoretically less immunogenic than the chimeric antibody infliximab. Etanercept is not effective for Crohn's disease. CDP571 is not effective in unselected patients with active Crohn's disease, but it may be effective in patients with elevated C-reactive protein. The efficacy of CDP870, adalimumab, and onercept is under investigation. The different mechanisms of action of these anti-TNF agents may account for their variable efficacy. Their benefits, however, must be considered in the context of their risks, including infusion reaction; delayed hypersensitivity-like reaction; new onset of autoimmunity, with rare cases of drug-induced lupus and new-onset demyelination; and the potential for rare but serious infections.

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.

Biological therapy in IBD. Anti-tumor necrosis factor-alpha and others

Currently used standard treatment in IBD is effective and sufficient for the majority of patients. Published numbers regarding therapy refractoriness are probably related to referral centers and not representative. Pharmacological optimization of available drugs improves the standard situation further. Biological therapies in a larger meaning are studied intensively, but obviously hopes are to some extent not real. Biological and for some principles clinical effects (i.e. TNF antibodies, CD4 antibodies) are proven, the effects are, however, limited and long-term risks and results are not clarified. Numerous approaches are not clinically relevantly effective which is, in particular, true for those inhibiting single mediators. A number of alternative concepts such as hormones and growth factors could be effective and will be studied further. In particular probiotics may be a development of the future and they belong to the 'biologic treatments' in the true sense.