Risk of combining immunosuppressive and biological treatments in inflammatory bowel disease

We thank Roblin and Phelip for their comment on a timely issue. The recent report of the rare hepatosplenic T-cell lymphoma (HSTCL) in young patients with CD treated with both infliximab and azathioprine or steroids has rightly unleashed a series of doubts regarding the optimal use of biological agents in this and other conditions. How these observations may directly relate to the design of our study—as implied by Roblin and Phelip—is unclear though. While azathioprine by itself has been linked to lymphoma development including HSTCL, recent studies have shown that neither infliximab nor methotrexate, which was used in our study, alone or in combination in CD or in rheumatoid arthritis, appear to be associated with an increased risk of developing lymphomas. In addition, methotrexate alone has never been associated thus far with HSTCL in CD.