Risks involved in treatment must be minimized, giving patients the possibility of leading a normal life.

SONIC, an international therapeutic trial, was recently carried out in patients with moderate or severe forms of CD never having been previously treated with immunosuppressants. Three treatment arms were studied and compared: azathioprine alone (an immunosuppressant), infliximab (anti-TNF) alone, or infliximab/azathioprine in combination. After six months, the infliximab/azathioprine combination led to a higher proportion of corticoid-free remission and mucosal healing than infliximab alone, while the latter was more effective than azathioprine alone. At twelve months, classification of results was identical for steroid-free clinical remission.

This potentiation of the effect of infliximab by azathioprine can be partly explained by the increase in residual blood infliximab levels under immunosuppressants, and by the decrease in production of antibodies to infliximab.

The clinical benefit of the combination of azathioprine and adalimumab (a “humanized” anti-TNF) has not been elucidated at present.

In clinical practice, the duration of this drug combination is generally limited to six to twelve months due to the high risk of opportunistic infections, but this attitude is currently being revised and in certain situations, combined treatment might be pursued due to the better clinical efficacy of, and better tolerance to, infliximab.

The benefit/risk ratio has to be taken into account in the choice of treatment strategy. The efficacy shown by the SONIC study of combined treatment with an immunosuppressant and an anti-TNF should be weighed against its potential toxicity.