P552 Withdrawal of immunomodulator medications (IM) in children with inflammatory bowel disease on combination therapy of IM and biologics

A. Chandrakumar1, M. Carroll2, J. deBruyn3, K. Jacobson4, H. Huynh2, E. Wine2, S. Lawrence4, W. El-Matary5

1Department of Pediatrics, University of Manitoba, Winnipeg, Canada, 2Department of Pediatrics, University of Alberta, Edmonton, Canada, 3Department of Pediatrics, University of Calgary, Calgary, Canada, 4Department of Pediatrics, BC children’s Hospital, Vancouver, Canada, 5Department of Paediatric Gastroenterology, University of Manitoba, Winnipeg, Canada

Background

Anti-tumor necrosis factor (anti-TNF) antagonists such as infliximab (IFX) are widely used for the treatment of inflammatory bowel disease (IBD). Early studies suggested that combination therapy with IFX and an immunomodulator drug (IM) such as azathioprine (AZA) or methotrexate (MTX) may help in optimising biologic pharmacokinetics, minimising immunogenicity, and improving outcomes. On the other hand, IM especially AZA, may increase infection and cancer risks with no clear evidence on long-term benefits of combination therapy. As such, stopping IM and continuation of an anti-TNF agent as a monotherapy in patients in remission seem to be a sensible strategy. However, there is no evidence to prove the efficacy of this strategy. The aim of this work was to examine frequency and factors associated with the first relapse after IM withdrawal in a cohort of children with IBD on combination therapy.

Methods

In a retrospective multicenter pediatric study, we determined the percentage of patients and investigated potential factors associated with the first relapse in a cohort of children and young adults with IBD on combination therapy of anti-TNF and IM after stopping IM. Cox regression analysis was used to assess factors associated with IBD relapse following IM withdrawal.

Results

A total of 79 patients (42, males, 62 Crohn’s disease) with 74 (93.7%) on IFX were included. In addition to the anti-TNF agent, 33 (41.8%) were on AZA and the rest were on MTX. The median duration of combination therapy was 2.0 (IQR 1.2–2.8) years. All participants were in clinical remission at the time of IM withdrawal. The median duration of follow-up after IM withdrawal was 11.0 (IQR 5.0–16.2) months. Only 8 (10.1%) patients relapsed over that period of follow-up. Age, sex, disease phenotype at diagnosis, family history of IBD, type of IM, and biochemical markers and clinical disease activity indices prior to IM stoppage did not predict a future relapse. Among those with CD on IFX who maintained remission, the median last IFX trough level before IM withdrawal was 6.25 Ug/ml (IQR: 4.04–8.70) vs. 3.8 Ug/ml (IQR: 2.40–11.6) in those who relapsed (p = 0.4).

Conclusion

Over short-term follow-up, the majority of children on combination therapy of IM and an anti-TNF agent remain in clinical remission after IM withdrawal.