Promises and Dangers of Combination Therapy

The efficiency of the existing methods of treating inflammatory bowel disease (IBD) is limited. There are 2 ways to address this problem - either create new treatment modalities or optimize current therapies. Optimisation may be accomplished by using combinations of established therapeutic strategies. With regard to topically acting compounds such as 5-aminosalicylic acid, combining oral and rectal preparations is a commonly used method. Another commonly used combination is anti-tumor necrosis factor (TNF)-α antibody modalities together with immunosuppressants (thiopurines, methotrexate). Several aspects favour those combinations such as increased effectivity, prevention of immunogenicity and perhaps less adverse events. Currently, discussion on directly additive therapeutic effects is in progress, which have been demonstrated in some clinical trials. As on date, the combination of infliximab with azathioprine is most likely the most effective treatment of Crohn's disease. On the other hand, a combination therapy with both compounds affecting the immune system has, of course, risks. For sure, the frequency with which serious infectious complications are arising is increasing. Furthermore, the number of patients experiencing malignancies such as hepato-splenic lymphoma or melanoma is strongly suspected to be on the rise. In summary, combinations of current treatments for IBD are widely established. Various strategies have been studied and significant improvements of therapeutic effects have been demonstrated. Unfortunately, some of those proven combinations increase therapeutic risks, for example, increase the frequency of serious infections and also of some malignancies. Therefore, great caution has to be exercised when applying combination therapies.