Background/Purpose: A biosimilar is a copy of an approved biologic therapeutic agent that has undergone rigorous evaluation to ensure that it is similar to the innovator in physicochemical characteristics, efficacy and safety. In many countries, there are biologic products available that have not undergone such evaluation and thus should be labeled “intended copy”.¹ It is critical to examine the safety profile of these intended copies to ensure that patients receive the best medical care available. The purpose was to evaluate the incidence of adverse events reported by patients treated with intended copies of etanercept (Infinitam or Etanar) and rituximab (Kikuzubam).

Methods: These data are a compilation of observations from four hospitals in Mexico and Colombia. Patients with rheumatic diseases, e.g., rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, were treated with Infinitam/Etanar or Kikuzubam. Patients were followed from initiation of treatment till first experience of an adverse event. Based on the nature and severity of the adverse event, treatment was continued, interrupted, suspended, or discontinued as determined by the treating physician.

Results: A preliminary analysis was performed of 219 patients with various diagnoses treated with Infinitam/Etanar (14) or Kikuzubam (205) in the four hospitals. Among patients receiving treatment, 10 (4.6%) on Infinitam/Etanar and 101 (46.1%) on Kikuzubam experienced at least one treatment-related adverse event (AE). Of these, 86.7% were female, and the median age was 51.9 years (range: 22 – 93 years). The median duration of disease was 14.5 years (range: 1 – 67 years). Overall, although the majority of the AEs reported (98/118, 83.1%) were Grade 2 or less, there were several reports of Grade 3 (13/118; 11.0%) and Grade 4 (7/118; 5.9%) AEs; there were no Grade 5 AEs reported for any agent. The time to the first experience of an AE from initiation of intended copy therapy was ranged from 0 – 50 months with 38 (36.2%) patients experiencing AEs on the same day as the first treatment.

Conclusion: A significant percent (14.3%) of patients receiving Infinitam/Etanar or Kikuzubam, intended copies of etanercept and rituximab, respectively, experience Grade 3/4 AEs with a very short time to onset.

Reference

1. Dörner T. et al. Ann Rheum Dis2013;72:322.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/incidence-of-adverse-events-in-patients-treated-with-intended-copies-of-biologic-therapeutic-agents-in-colombia-and-mexico/