Improvement of Transmural Inflammation With Adalimumab Versus Immunomodulator Maintenance Therapy in Pediatric Crohn's Disease: Single-Center Prospective Evaluation Using the Pediatric Inflammatory Crohn's Magnetic Resonance Enterography Index.

Background and aims: Transmural healing, including as assessed by magnetic resonance enterography (MRE) has been associated with long-term favorable outcomes in Crohn's Disease (CD), but data concerning MRE improvement and normalization with therapy are sparse. We performed a prospective longitudinal study utilizing the recently developed pediatric MRE-based multi-item measure of inflammation (PICMI) to examine the efficacy of adalimumab (ADA) and immunomodulator (IM) in attaining improvement of transmural inflammation of the small intestine.

Methods: Pediatric patients with CD involving small bowel and initiating ADA or IM were prospectively enrolled and followed with repeat MRE at 1 year. A single radiologist provided global assessment (RGA) and scored PICMI items (wall thickness, wall diffusion restriction, mural ulcers, comb sign, mesenteric edema) blinded to clinical information and to the timing of MRE. The primary outcome was mild improvement in PICMI at one year without a change in therapy.

Results: Sixty-two eligible patients were enrolled, 26 receiving ADA and 36 IM. On intent to treat basis, a decline in PICMI score of >20 points without change of therapy was observed more frequently in ADA versus IM-treated patients (54% vs 31%, P = .01). By RGA, 71% improved with ADA vs 42% with IM (P = .03). MRE normalization was rare with both treatments (9% vs 6%, P = .62). A change in PICMI of >20 points was confirmed as the best cut off for MRE improvement as assessed by RGA also for the small bowel.

Conclusions: ADA therapy was associated with objective improvement in MRE findings of inflammation more frequently than IM. The low rate of MRE normalization suggests that this is not yet a realistic target with existing therapies.