No Change in Efficacy when IA Patients Are Switched to SB4: Results from the DANBIO Registry

In 2015, Danish rheumatologists were mandated to switch patients with inflammatory arthritis (IA) treated with originator infliximab to the biosimilar CT-P13. There was no change in clinical outcomes after 1 year of follow-up (reported at ACR 2016 and by RheumReports).

In April 2016, a similar non-medical switch was mandated for all IA patients in Denmark treated with etanercept 50 mg/wk to the biosimilar SB4. The results from 5 months of follow-up were reported today by Glintborg et al (#FRI0190). A total of 1548 patients (891 RA, 335 PsA and 322 axSpA) were switched after a median duration on innovator etanercept of 5.2 years. The outcomes of interest included disease activity 3 months before and 3 months after the switch, rates of disease flare over time, treatment retention rates, and reasons for withdrawal.

Rates of disease activity were largely unchanged before and after the switch, with no statistically significant differences from pre- to post-switch. Similarly, rates of disease flare were unchanged before and after the switch. Overall, 129 patients discontinued SB4 during the follow-up period, mostly due to lack of effect (n=59) or adverse events (n=42). Factors that were independently associated with treatment withdrawal included higher patient global score and no background methotrexate treatment at baseline. A further analysis is planned after 1 year of follow-up.

The investigators concluded that patients with IA had largely stable disease activity and similar rates of disease flare before and after switching from innovator etanercept to biosimilar SB4 for non-medical reasons. A small proportion of patients (9%) discontinued treatment after switching.

During an earlier satellite symposium on biosimilars and non-medical switching, DANBIO co-author Dr. Merete Lund Hetland discussed these results in the context of her own clinical practice. Patients often ask why their medication is being switched and whether the new medication will be as safe and effective as the current one. She acknowledges that economic reasons drove the reason for switching, and she reassures them that there is evidence to support the similar efficacy and safety of biosimilars compared to innovator biologics. Danish patients will continue to be followed in the DANBIO registry to monitor outcomes over time.

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