Tumor necrosis factor (TNF) promotes the inflammatory response, which in turn causes many of the clinical problems associated with autoimmune disorders such as rheumatoid arthritis, ankylosing spondylitis, Crohn's disease, psoriasis, hidradenitis suppurativa and refractory asthma. These disorders are sometimes treated by using a TNF inhibitor, also known as TNF blocker.
The ongoing progresses in the knowledge of the pathogenic mechanisms of various inflammatory or immune-mediated diseases and the availability of innovative biotechnological approaches have lead to the development of new drugs which add to conventional treatments. TNF-alpha inhibitors (infliximab, adalimumab and etanercept) have demonstrated efficacy either as monotherapy or in combination with other anti-inflammatory or disease modifying anti-rheumatic drugs (DMARDs). The efficacy and safety profile of the TNF-alpha inhibitors can be considered, in general, as a class effect. Nevertheless, some differences may exist among the three agents.
Infliximab and etanercept have been utilized to treat rheumatoid arthritis and Crohn's disease for several years. There is therefore much post-approval data on their side effects. A variety of Medline searches were done at the beginning of June 2004 using the terms 'etanercept', 'infliximab' and 'adalimumab' and the words 'lymphoma', 'infection', 'congestive heart failure', 'demyelinating disease', 'lupus', 'antibodies', 'injection site reaction', 'systemic', 'side effects' and 'skin'. The important side effects that have been most extensively related to TNF-alpha inhibitors / blockers include: lymphoma, infections, congestive heart failure, demyelinating disease, a lupus-like syndrome, induction of auto-antibodies, injection site reactions, and systemic side effects. The risk of these side effects is very low. Nevertheless, it is important for clinicians to be aware of these side effects when prescribing anti TNF therapy.
Of course, TNF inhibitors are serious drugs and they do increase the risk of serious infections. The rates however have been less than predicted. So, are TNF inhibitors safe? The answer is of course yes. Given the widespread use, the close monitoring patients receive, the extensive data collection to monitor safety. This does not mean that we stop being vigilant. Rheumatologists will keep watching but it's a case of so far, so good.