Thiopurines have no impact on outcomes of Crohn's disease patients beyond 12 months of maintenance treatment with infliximab

The emergence of new treatments the inflammatory bowel diseases (IBD) raised questions regarding the role of older agents, namely thiopurines. To clarify the benefits of combination treatment with thiopurines on Crohn's disease (CD) patients in the maintenance phase of infliximab. In this analysis of the 2-year prospective multicentric DIRECT study, patients were assessed in terms of clinical activity, faecal calprotectin (FC), C-reactive protein (CRP), and infliximab pharmacokinetics. A composite outcome based on clinical- and drug-related items was used to define treatment failure. The study included 172 patients; of these, 35.5 % were treated with combination treatment. Overall, 18 % of patients achieved the composite outcome, without statistically significant differences between patients on monotherapy and on combination treatment (21.6% vs 11.5 %, p = 0.098). Median CRP, FC, and infliximab pharmacokinetic parameters were similar in both groups. However, in the sub-analysis by infliximab treatment duration, in patients treated for less than 12 months, the composite outcome was reached in fewer patients in the combination group than in the monotherapy group (7.1% vs 47.1 %, p = 0.021). In CD patients in maintenance treatment with infliximab, combination treatment does not seem to have benefits over infliximab monotherapy beyond 12 months of treatment duration.