Low Anti-Tumor Necrosis Factor Levels During Maintenance Phase Are Associated With Treatment Failure in Children With Crohn's Disease

Inflamm Bowel Dis. 2024 Oct 17:izae239. doi: 10.1093/ibd/izae239. Online ahead of print.

Abstract

Background: Higher drug levels and combination therapy with low-dose oral methotrexate (LD-MTX) may reduce anti-tumor necrosis factor (TNF) treatment failure in pediatric Crohn's disease. We sought to (1) evaluate whether combination therapy with LD-MTX was associated with higher anti-TNF levels, (2) evaluate associations between anti-TNF levels and subsequent treatment failure, and (3) explore the effect of combination therapy on maintenance of remission among patients with therapeutic drug levels (>5 µg/mL for infliximab and >7.5 µg/mL for adalimumab).

Methods: We conducted a post hoc analysis of the COMBINE trial, which compared anti-TNF monotherapy to combination therapy with LD-MTX. We included participants who entered maintenance therapy and provided a serum sample approximately 4 months from randomization.

Results: Among 112 infliximab and 41 adalimumab initiators, median drug levels were similar between combination therapy and monotherapy (infliximab: 8.8 vs 7.5 μg/mL [P = .49]; adalimumab: 11.1 vs 10.5 μg/mL [P = .11]). Median drug levels were lower in patients experiencing treatment failure (infliximab: 4.2 vs 9.6 μg/mL [P < .01]; adalimumab: 9.1 vs 12.3 μg/mL [P < .01]). Among patients treated with infliximab with therapeutic drug levels, we observed no difference in treatment failure between participants assigned monotherapy or combination therapy. Among patients treated with adalimumab, a trend towards reduced treatment failure in the combination therapy arm was not statistically significant (P = .14).

Conclusions: LD-MTX combination was not associated with higher drug levels, but higher drug levels were associated with reduced risk of treatment failure. Among patients with therapeutic drug levels, we observed no benefit of LD-MTX for patients treated with infliximab. A nonsignificant trend towards reduced treatment failure with the addition of LD-MTX patients treated with adalimumab warrants further investigation.

Keywords: biologics; inflammatory bowel disease; pediatrics; therapeutic drug monitoring.

Plain language summary

For children with Crohn’s disease treated with biologic medications, with and without low-dose methotrexate, the role of drug levels on treatment failure in a recent prospective trial is unclear. These data suggest patients on infliximab with therapeutic drug levels are more likely to continue any therapy, and the effect on patients treated with adalimumab requires more investigation.