Tuesday, 10 January 2012

Anti-arthritis Drugs Carry a Risk of Aspergillosis

There are a number of new drugs coming into use which are intended to correct the immune system response of the patient to specific challenges. These drugs hold high promise for the treatment of auto-immune diseases where our immune systems mistake their own host tissues as an invading organism and attack tham as if they were eliminating a bacterium or other micro-organism.

First defined by Ernst Witebsky(1957) autoimmune diseases are common and take many forms, attacking particular tissues. There are hundreds of different types of autoimmune disease and they include familiar diseases such as rheumatoid arthritis. They are traditionally treated by suppressing the immune system of the patient using glucocorticoid drugs which are very effective.

Unfortunately glucocorticoids have many unpleasant side effects so many efforts are made to minimise their usage. It is beginning to be possible to manufacture drugs that will selectively inhibit parts of our immune systems and prevent painful inflammation caused by an overactive immune system e.g. Certolizumab. These are antibodies that can very precisely eliminate proteins causing particular types of inflammation.
The amazing trick this new generation of antibodies can perform is to fool our bodies into thinking that the injected antibody is a human antibody (humanised antibody) which allows them to persist in our bodies for longer period of time. They then have a much larger effect.

These humanised antibody drugs are achieving success in treating many people who are having difficulty with inflammation - arthritis being one group but other groups are also being treated e.g. omalizumab (Xolair) to treat those with severe asthma and in some cases Allergic Bronchopulmonary Aspergillosis (ABPA). Many can reduce or eliminate their dose of steroid while taking the antibody - different antibodies are used in each case.

Revolutionary though they may be, there is a small risk with some of these medications. If you adjust parts of the immune system there is a risk that you can also reduce the ability of that person to fight off infection. Using Certolizumab on its own doesn't seem to cause a problem but if that patients is immunocompromised by taking a steroid drug at the same time as the antibody then there can be a small increased change of getting a number of infections including aspergillosis.

 This article is a summary of a research project into the use of Certolizumab to treat arthritis. It gives a warning for users of Certolizumab  to be cautious if they have had or still have tuberculosis, aspergillosis and other infections and are taking steroids at the same time. One outcome of this study may well be to investigate this risk more carefully.

NOTE: It is worth reiterating that there is no data suggesting that treating ABPA with Omalizumab can trigger more aggressive aspergillosis, this study only refers to Certolizumab - a quite different medication.

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