Prospective data are lacking on evolution of trough levels, effectiveness, acceptance rate and patient satisfaction after switch from the adalimumab originator to a biosimilar in patients with inflammatory bowel disease.
Patients in clinical remission or stable response and treated with adalimumab originator in 2 Belgian centers were offered to participate in this phase IV, prospective trial in which patients were switched to adalimumab biosimilar SB5. The primary outcome was the description of adalimumab trough levels over time. Secondary outcomes were secondary loss of response, disease activity, patient satisfaction score and drug persistence over 12 months.
The study included 110 patients. Mean baseline adalimumab trough level was 9.21 μg/ml. Concentration remained within the therapeutic range over time. No changes were observed in disease activity scores nor in biochemical parameters over time. The acceptance rate of switch was 84.6%. By month 12, 74.5% was still treated with SB5. The most frequent reason for discontinuation was occurrence of adverse events. 50% of these adverse events were injection site pain. The local discomfort was only significant the first 30 minutes after injection. Satisfaction with the decision to switch to SB5 was high and remained stable over time.
After being well informed the great majority of patients treated with the adalimumab originator is willing to switch to biosimilar SB5. In our study, there was a persistence rate of 75% over one year. The trough levels remained within the therapeutic range and no change in disease activity was seen over time.