Benefit-risk assessment of infliximab in the treatment of rheumatoid arthritis

In the last decade, there have been substantial advances in the treatment of rheumatoid arthritis with the addition of several new disease-modifying agents to the therapeutic armamentarium. Biological agents targeting tumour necrosis factor (TNF) represent one such important addition. Infliximab, a chimeric anti-TNF monoclonal antibody, has shown remarkable promise in alleviating the signs and symptoms of rheumatoid arthritis in addition to retarding radiographic disease progression when used in combination with methotrexate. In its pivotal phase III trial, the addition of infliximab to patients with methotrexate-refractory disease was associated with substantial clinical benefit. Using American College of Rheumatology criteria for improvement, one-half of patients receiving infliximab (3 mg/kg every 8 weeks) plus methotrexate showed at least 20% improvement compared with only 20% of those receiving placebo plus methotrexate (p < 0.001) with over one-half of eventual responders obtaining criteria for improvement by the second week of observation. Although its use has been met with much deserved enthusiasm, recent reports have highlighted several potential serious adverse effects associated with infliximab (and other TNF antagonists), including infusion reactions, congestive heart failure, drug-induced lupus, and CNS demyelination. In addition, recent reports have cited the potential for reactivation of mycobacterial and fungal infection in patients receiving infliximab, mandating appropriate tuberculosis screening prior to drug initiation. Although the frequency of serious drug-related toxicity (requiring discontinuation of the agent) appears to be quite low, these reports underscore the need for caution and close surveillance with the administration of TNF inhibitors, particularly given that strategies aimed at preventing toxicity remain unproven. Despite its potential for toxicity, infliximab remains a valuable alternative for patients with rheumatoid arthritis.