Digestive Disease Week: Report
Infliximab - The Current Knowledge
Digestive Disease Week: Report
Infliximab - The Current Knowledge
Effectiveness
Infliximab was approved by the US regulatory drug authorities in August 1999 for use in severe Crohn's disease not responding to other therapy. Overall, about 50,000 patients with either IBD or rheumatoid arthritis have now been treated with infliximab. Clinical trials have shown an initial high response rate to a single intravenous dose of infliximab 5 mg/kg (about 80%), with fistula healing in about half of patients treated. Giving repeated doses every 8 weeks appears to maintain the good clinical response. In clinical practice (a less controlled environment) similar results have been observed,with response to the first infliximab dose occurring quickly. Fistulas also responded after 1 dose.
Side effects
Looking at pooled data from 12 studies (5 in Crohn's patients, 6 in patients with rheumatoid arthritis and 1 in ulcerative colitis), there was little difference between patients who had received infliximab and those who had received inactive placebo in terms of adverse effects. Approximately a quarter of patients developed antibodies against infliximab, but the clinical significance of this has yet to be determined. The development of antibodies appears to be reduced when immunosuppressants are being taken at the same time as infliximab. Once again, clinical experience seems to mimic the findings of controlled studies.
Cancer risk
Although there was some initial concern that the risk of developing cancer might be increased in infliximab recipients, this has not been borne out during extensive clinical use. Essentially, patients taking many other immunomodulatory agents are at a slightly increased risk of cancer anyway, and infliximab does not seem to increase this further.
Where to now?
Although data on infliximab is accumulating quickly, there are a number of other questions that remain to be answered. These include: defining the role of taking immunomodulators, such as azathioprine, at the same time as infliximab; the impact of antibodies on the response to re-treatment with infliximab; gathering longer term data on side effects; and deterrmining effectiveness and side effects in children and during pregnancy. Also, infliximab has been shown to modify the disease course in rheumatoid arthritis patients, and it would be good to determine if treatment earlier and/or in mild disease could have the same effect in patients with Crohn's disease. And what about use in ulcerative colitis?
So, we've come a long way, but there is a long way to go before we more fully understand all the issues associated with infliximab therapy.
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