Pharmacogenetic investigation of the TNF/TNF-receptor system in patients with chronic active Crohn's disease treated with infliximab

The biology of TNF blockade

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

Biologic therapies in the spondyloarthritis: new opportunities, new challenges

Therapeutic options for patients suffering from the more severe forms of spondyloarthritis have been rather limited in the last decades. There is now accumulating evidence that antitumor necrosis factor therapy is highly effective in spondyloarthritis, especially in ankylosing spondylitis and psoriatic arthritis. Based on the data recently published on more than 500 patients with ankylosing spondylitis and psoriatic arthritis, this treatment seems to be even more effective than in rheumatoid arthritis. The antitumor necrosis factor-alpha agents currently available, infliximab (Remicade), etanercept (Enbrel), and adalimumab (Humira), are approved for the treatment of rheumatoid arthritis in the United States and partly in Europe. The situation in spondyloarthritis is different from that of rheumatoid arthritis because there is an unmet medical need, especially in ankylosing spondylitis: no therapies with disease-modifying antirheumatic drugs are available for severely affected patients, especially with spinal disease. Thus, tumor necrosis factor blockers may even be considered a first-line treatment in a patient with active ankylosing spondylitis and psoriatic arthritis whose condition is not sufficiently controlled with nonsteroidal antiinflammatory drugs in the case of axial disease, and sulfasalazine or methotrexate in the case of peripheral arthritis. For infliximab, a dose of 5 mg/kg was required, and intervals between 6 and 12 weeks were necessary to suppress disease activity constantly-also a major aim for long-term treatment. The standard dosage of etanercept is 2 x 25 mg subcutaneously per week. There are no studies yet on adalimumab (standard rheumatoid arthritis dose, 20-40 mg subcutaneously every 1-2 weeks) in spondyloarthritis. Infliximab was very recently approved for AS in Europe. The efficacy of etanercept was first demonstrated in psoriatic arthritis, and it is now approved for this indication. A double-blind study has also been performed in ankylosing spondylitis, with similarly clear efficacy. There is preliminary evidence that both agents do also work in other spondyloarthritis, such as undifferentiated spondyloarthritis. Ideally, both agents will be approved soon for the short-term treatment of severe, uncontrolled spondyloarthritis. In parallel, studies should be performed to document the long-term efficacy of this treatment. There is hope that ankylosis may be preventable, but it remains to be shown whether patients benefit from long-term antitumor necrosis factor therapy and whether radiologic progression and ankylosis can be stopped. Severe adverse events have remained rare. Complicated infections including tuberculosis have been reported. These can be largely prevented by appropriate screening. At it stands now, the benefits of antitumor necrosis factor therapy in ankylosing spondylitis seem to outweigh these shortcomings.

Novel approaches in the treatment of ankylosing spondylitis and other spondyloarthritides

The therapeutic options for patients suffering from severe forms of spondyloarthritis (SpA) have been rather limited in recent decades. There is now accumulating evidence that anti-TNF therapy is highly effective in SpA, especially in ankylosing spondylitis (AS) and psoriatic arthritis (PsA). Based on the data recently published on what is now several hundred AS and PsA patients, this treatment seems to be even more effective than the same therapy in rheumatoid arthritis (RA). The anti-TNF-alpha agents currently available, infliximab (Remicade); Centocor), etanercept (Enbrel); Amgen) and adalimumab (Humira; Abbott), are approved for the treatment of RA in the US; infliximab and etanercept are approved in Europe. The situation in SpA is different to RA because there is an unmet medical need, especially in AS, since no therapies with disease-controlling antirheumatic drugs are available for severely affected patients, especially with spinal disease. Thus, TNF blockers might even be considered as first-line immunosuppressive agents in patients with active AS and PsA who are not sufficiently treated by non-steroidal anti-inflammatory drugs and sulfasalazine, if peripheral arthritis is present. For infliximab, a dosage of 5 mg/kg at intervals between 6 and 12 weeks was necessary to constantly suppress disease activity; this is also a major aim of long-term treatment. No dose-finding studies have yet been performed. The standard dose of etanercept is 25 mg s.c. twice-weekly. No studies on adalimumab (standard RA dose 20 - 40 mg s.c. every 2 weeks) have yet been conducted in SpA. The efficacy of etanercept was first demonstrated in PsA and etanercept is now approved for this indication. A double-blind study has also been performed in AS, with similarly clearcut efficacy. There is preliminary evidence that both agents do also work in other SpA such as undifferentiated SpA. Infliximab has recently been approved for short-term treatment of severe uncontrolled AS; the approval for etanercept is pending. Studies should be performed to document the long-term efficacy of this treatment. There is hope that ankylosis might be preventable but it remains to be shown whether patients benefit from long-term anti-TNF therapy and whether radiological progression and ankylosis can be stopped. Severe adverse events have remained rare. Complicated infections including tuberculosis have been reported. Tuberculosis can be mostly prevented if patients are checked for previous contact with tuberculosis. Currently, the benefits of anti-TNF therapy in AS seem to outweigh these shortcomings.

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

BACKGROUND

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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