Switchback from biosimilar tumor necrosis factor-alpha inhibitors to reference medicines: a review

Switching from reference biologics to biosimilars usually occurs for non-medical reasons, such as cost-driven formulary changes. However, despite biosimilars having the same efficacy and similar safety profiles as their reference products, some patients discontinue treatment and 'switchback' to the reference product.

In this narrative review, the authors examine the frequency and causes of switchback reported in journal articles and congress abstracts published between 2016 and 2023, evaluating patients who switched from biosimilars back to the reference biologic. As almost all publications focused on tumor necrosis factor inhibitors, and so the authors restricted their analysis to this drug class.

Evidence suggests that switchback rates are low, with most studies of at least 100 patients reporting rates of less than 20%. The main reasons for switchback are typically patient-reported loss of effectiveness (usually judged subjectively) and side effects. These findings support the view that the nocebo ('negative placebo') effect is a plausible and likely contributor to switchback. Healthcare professional and patient education on the effectiveness and safety of biosimilars is needed and will be vital to counter misinformation and minimize the nocebo effect, allowing biosimilars to continue contributing to sustainability in healthcare.