Thiopurines Efficacy in Children with Ulcerative Colitis

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FA Hanna et al. JPGN 2023; 77: 505-511. Thiopurines Maintenance Therapy in Children With Ulcerative Colitis: A Multicenter Retrospective Study

In this retrospective study with 133 children (2008-2019), typical dosing of thiopurines: azathioprine 2-2.5 mg/kg/day and 6-mercaptopurine 1.5 mg/kg/day. Patients with previous or concomitant treatment with 5-ASA were allowed in the study. 62% (n=83) of the cohort had pancolitis. Key Findings:

  • Seventy-four patients (56%) had CS-free clinical remission at week 52 without rescue therapy
  • In the cohort in clinical remission, 67 and 51 patients had both CRP and calprotectin measurements at 1 year and end of follow-up. Sufficient biomarker response (CRP <1 mg/dL, calprotectin <250 mcg/g) was achieved by 44 (66%) and 44 (86%) at those two time points.
  • The likelihood of remaining free of rescue therapy among thiopurines-treated patients was 83%, 62%, 45%, and 37% at 1, 2, 3, and 4 years, respectively
  • 8 of 133 (6%) stopped thiopurine therapy due to adverse effects

In their discussion, the authors make several points regarding efficacy and safety of thiopurines.

  • Many experts have advocated use of anti-TNF therapy agents for ulcerative colitis especially when 5-ASA medications are not effective.. This is based on higher efficacy and safety. With regard to safety, the authors note an “extremely low risk of lymphoma” citing a study from Israel in which children were followed until age of 30 years. No cases of hepatosplenic T-cell lymphoma were identified and the lymphoma rate was not statistically significant (O Atia et al. J Crohns Coliitis 2022; 16: 786-795 Open Access! Risk of Cancer in Paediatric onset Inflammatory Bowel Diseases: A Nation-wide Study From the epi-IIRN).
  • The authors note a recent review “rejected the hypothesis that initiation of biologic treatment later in the disease course correlates with lower response and remission rates in UC patients.”
  • Based on the efficacy and safety, the authors advocate for use of thiopurines “either early in the treatment course or as part of a de-escalation therapy…Thiopurines should be considered in the treatment of UC patients before the initiation of biologic drugs in most children.”

My take: In the U.S., it appears that thiopurine monotherapy, and even combination therapy, in pediatrics with IBD is used infrequently. Anti-TNF therapy with therapeutic drug monitoring is used routinely in patients if a 5-ASA is ineffective or not a good option. This article is a reminder that thiopurines are still a reasonable option. This would have been a good opportunity for a commentary in JPGN to add some context to this article regarding the role of these agents.

AGA guidelines for moderate-to-severe ulcerative colitis: “In adult outpatients with moderate to severe UC in remission, AGA makes no recommendation in favor of or against using biologic monotherapy or tofacitinib rather than thiopurine monotherapy for maintenance of remission.”

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