Improved injection site reactions after switching from adalimumab reference to adalimumab biosimilar LBAL for ulcerative colitis: A case report.

Rationale: Adalimumab (ADA) is an antitumor necrosis factor agent that is used for the treatment of inflammatory bowel disease. However, its cost has resulted in varying degrees of restricted access across global healthcare economies. Biosimilars are agents that contain a similar version of the active substance of an already approved original biologic agent and are intended to be used for the same indication as the reference product. In general, biosimilars follow the originator; therefore, information on its efficacy and safety had been few. Some studies have reported on replacement of the originator with a biosimilar of the same efficacy because of medical reasons.

Patient concerns: A 15-year-old girl with steroid-dependent ulcerative colitis that relapsed after vedolizumab was treated with ADA reference. Six weeks after starting ADA reference, her gastrointestinal symptoms had completely resolved, however, immediately after the eighth dose of ADA reference, redness, swelling, and pruritus were noted at the injection site on the left thigh.

Diagnosis: Allergic reaction caused by the ADA reference.

Intervention: ADA reference was changed to ADA biosimilar LBAL.

Outcomes: ADA biosimilar LBAL was continued without any symptoms, such as local swelling, redness, or itching. In addition, there was no deterioration of gastrointestinal symptoms.

Lessons: We showed the efficacy and safety of ADA biosimilar LBAL as an alternative to ADA reference, which caused injection site reactions. Changing from ADA reference to ADA biosimilar because of adverse events may be an option that needs careful observation, considering that the originator and the biosimilar are not exactly the same.