Nonmedical Adalimumab Biosimilar Switch Maintains Disease Control in Pediatric IBD

Children and young adults with inflammatory bowel disease (IBD) generally maintained stable disease control after an insurance-mandated, nonmedical switch from the adalimumab originator to a biosimilar, according to findings published in JPGN Reports.1

“Adalimumab biosimilars are as safe and effective compared to the originator. Adult patients with inflammatory bowel disease (IBD) who switched to a biosimilar have comparable outcomes, but pediatric data are limited,” wrote the researchers of the study.

Adalimumab (Humira; AbbVie), an anti–tumor necrosis factor (anti-TNF) biologic, is an established treatment option for pediatric Crohns disease and ulcerative colitis. Infliximab biosimilars have been available in the US since 2016, with established safety and efficacy data in pediatric IBD, and adalimumab biosimilars entered the US market in 2023. Much of the existing evidence has focused on biosimilar-naive patients rather than patients switched from the originator. Ten adalimumab biosimilars had been introduced in the US by June 2024, and payers have increasingly used formulary preferences and step-therapy policies involving adalimumab products.2

Researchers at Nationwide Children's Hospital conducted a retrospective chart review of 50 pediatric and young adult patients with IBD who underwent a nonmedical switch from an adalimumab originator to a biosimilar between May 2023 and July 2024.1 The cohort was predominantly male (58%), White (90%), diagnosed with Crohn disease (88%), and covered by commercial insurance (100%). Most patients (92%) were switched to adalimumab-adaz based on payer formularies.

Clinical Outcomes Were Largely Stable

Among the 42 patients with Physician Global Assessment (PGA) data available both before and after the switch, 86% (36 of 42) had stable or improved disease activity. This included 74% who remained in remission and 12% who improved to remission. Six patients (14%) experienced worsening disease activity, although no patients developed severe disease activity. The change in PGA scores before and after the switch was not statistically significant (P = .79).

Laboratory markers, including albumin, hemoglobin, C-reactive protein, and erythrocyte sedimentation rate, showed no significant differences before and after the switch.

Adalimumab trough levels declined significantly, from a mean of 18.1 µg/mL to 15.0 µg/mL (P = .007). Although levels remained above the 10 µg/mL threshold used by the study authors to define a therapeutic concentration, the decrease may be clinically relevant for some patients, particularly those with perianal disease, for whom higher adalimumab concentrations may be associated with fistula healing.

Detectable antidrug antibodies increased from 4.8% to 14.3% of patients, but the difference did not reach statistical significance (P = .16). Given the small sample size, however, the lack of statistical significance does not necessarily exclude a clinically meaningful change.

Discontinuation and Adverse Effects

Thirty-eight of 50 patients (76%) remained on the biosimilar at least 6 months after the switch. Twelve patients discontinued treatment during follow-up. Five discontinued for reasons considered unrelated to the switch, including insurance changes or persistent baseline disease activity, and the remaining 7 discontinued for reasons considered related to the switch, including adverse effects, disease worsening, or declining drug levels.

The authors also reported that recurrence of symptoms without corresponding biochemical changes could, in some cases, reflect a nocebo effect. This interpretation remains speculative and should not be considered evidence that reported symptoms were not genuine treatment-related events.

The 76% observed 6-month continuation rate was lower than the 93% 6-month durability probability reported in a 2025 European pediatric IBD cohort. However, the populations and study methods differed: the European study include patients initiating a biosimilar and patients switching from the originator, limiting direct comparison between the studies.

The Nationwide Children's study has several limitations. Its retrospective, single-center design; small sample size; predominantly White, commercially insured population; Crohn disease–predominant cohort; and short follow-up limit generalizability. In addition, the absence of a nonswitching control group means the study cannot establish that biosimilar switching is equivalent to continuing the originator product.

“In summary, clinical, laboratory, and pharmacokinetic outcomes were largely maintained over 6 months following a nonmedical switch to adalimumab biosimilars,” wrote the researchers. “While short‐term medication continuation was demonstrated, larger and longer‐term studies are needed to better understand biosimilar use in children—especially as the economic landscape continues to evolve.”

References

1. Himelstein D, McNicol M, Abdel-Rasoul M, et al. Outcomes of adalimumab biosimilar nonmedical switches in children and young adults with inflammatory bowel disease. JPGN Rep. 2026;10.1002/jpr3.70212. doi:10.1002/jpr3.70212
2. Tesser JRP, Charabaty A, Hebert AA. Switching from adalimumab reference product to and among adalimumab biosimilars outside the USA: insights for US clinicians. BioDrugs. 2025;39(4):591-606. doi:10.1007/s40259-025-00719-z