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In their correspondence, Cantini and Benucci1 express their concern about the lack of real-life data supporting the switch from originator to biosimilar biological disease-modifying antirheumatic drugs, as recommended in the recently issued consensus-based recommendations.2 They argue that the Danish Nationwide Biologic (DANBIO) registry reporting real-life data showed a lower than expected retention rate after the switch to biosimilar infliximab (bio-IFX) and etanercept.3 4
Concerning bio-IFX, several other real-life studies have been published so far. One Dutch and one French open studies have examined real-life outcomes of the switch from originator to bio-IFX in patients with inflammatory rheumatic diseases.5 6 Both studies revealed a bio-IFX retention rate between 72% and 76%, which is lower than the expected originator IFX retention rate. Interestingly, the two studies reported that a significant proportion of patients stopping bio-IFX presented subjective complaints without any clinical sign of disease activity. In the French study, exclusion of the subgroup of patients presenting only subjective complaints (44% of dropouts) suppressed the difference in retention rate when compared with a historic cohort of original IFX (ori-IFX) treated patients. Finally, both studies allowed patients to switch back to ori-IFX. Patients presenting with subjective complaints were rescued by ori-IFX resumption, whereas those with objective symptoms were more likely to switch to another biologic.
These results strongly suggest that the lower retention rate after the switch is due to a nocebo effect,7 or an incorrect attribution bias where a random flare-up is falsely attributed to an unrelated factor (eg, the switch).
To put it in other words, if 100 patients are switched from ori-IFX to bio-IFX, roughly 70% will continue the biosimilar, 15% will present IFX failure with objective signs of activity (as expected without the switch) and 15% will develop subjective symptoms that can be rescued with ori-IFX resumption. Thus, one can see the glass half full or half empty. We prefer to see evidence that in case of switch, 70% of patients will remain treated with the biosimilar leading to substantial savings for the health system, and that the other 30% will switch back either to the originator or to another biologic.
We therefore fully support the task force guidelines including recommendation 6 stating that the switch from an originator biologic to its biosimilar appears safe and that this recommendation deserves a 1b level of evidence.
Biologics have changed the prognostic of patients with rheumatic diseases. However, this breakthrough has come with substantial costs that our health systems have difficulties to cope with. Biosimilar might be one of the solutions for this serious issue. In the UK, considering that IFX and etanercept are estimated to cost £408 million/year (€482 million) and that biosimilar prices are on average 20% lower than originator prices, a 70% biosimilar switch rate would account for savings of 81.6 million/year (€96.4 million).8
Biosimilars have, for now, consistently shown that a lower price does not equal a lesser quality. Continuous diffusion, pharmacovigilance and research around biosimilars will allow to address the remaining questions on their use and reassure patients and physicians about their safety.
Competing interests None declared.
Provenance and peer review Not commissioned; internally peer reviewed.
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