Biosimilar, originator DMARDs exhibit no differences in treatment retention
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There are no clinically relevant differences in treatment retention among patients receiving biosimilar or originator biologic disease-modifying antirheumatic drugs as first exposure to that drug, data published in Rheumatology show.
The researchers added that there was similarly no evidence for worse retention following a non-medical switch, and no “obvious nocebo effect.”
“Biosimilar products of biologic DMARDs entered the Swedish market in 2015,” Daniela Di Giuseppe, MSc, PhD, of the Karolinska Institutet, in Stockholm, Sweden, told Healio. “Since then, many biosimilars have been marketed, and have now largely taken the place of their originator product due to their lower price. Since studies on the comparison between biosimilars and their originators have been limited, both in number of indications and to a short study period, we aimed to detect any unexpected differences in performance, as part of a continuous need for pharmacovigilance.”
To compare treatment retention between patients who received either a biosimilar or its originator as their first exposure to that biologic DMARD, as well as after non-medical switching, Di Giuseppe and colleagues studied data from the national Swedish Rheumatology Quality Register (SQR). According to the researchers, the SQR has collected national data on patients with rheumatic diseases since 1995 and is linked to other national Swedish registers.
“Throughout this period there has been a considerable increase in the use of biosimilars in Sweden, gradually replacing the originator drugs,” they wrote. “Hence, with a large number of patients in Sweden having either started a biosimilar product as their first exposure to that drug or having performed a non-medical switch to a biosimilar, it is now possible to compare the treatment retention of the biosimilars with their originators, both for new starts and after switching, for several different biosimilars in the same setting.”
The researchers identified 21,443 first-treatment courses with etanercept (Enbrel, Amgen), infliximab (Remicade, Janssen), adalimumab (Humira, AbbVie) or rituximab (Rituxan/Mabthera, Genentech), or their biosimilars, among patients with rheumatic diseases.
Included biosimilars were Benepali (SB4, Samsung Bioepis) and Erelzi (etanercept-szzs, Sandoz) for etanercept; Remsima/Inflectra (infliximab-dyyb; Celltrion/Pfizer), Flixabi (SB2, Samsung Bioepsis) and Zessly (PF-06438179/GP1111, Sandoz) for infliximab; Imraldi (SB5, Samsung Bioepis), Amgevita (adalimumab-atto, Amgen), Hyrimoz (adalimumab-adaz, Novartis Sandoz) and Idacio (MSB11022, Fresenius Kabi Deutschland) for adalimumab; and Ritemvia/Truxima (rituximab-abbs, Celltrion) and Rixathon (GP2013, Sandoz) for rituximab.
The researchers included data from March 1, 2012, to Dec. 31, 2020.
A total of 2,925 patients who switched from an originator drug to one of its biosimilars were also included and individually matched to those continuing with the originator. The researchers analyzed 1-year retention and calculated HRs for discontinuation, adjusting for comorbidities and socioeconomic factors.
According to the researchers, the proportion of patients still receiving their first-exposure drug at 1 year, as well as the HRs for discontinuation, demonstrated no differences across adalimumab products — Humira, Imraldi, Amgevita and Hyrimoz — nor rituximab products — Rituxan/Mabthera, Ritemvia/Truxima and Rixathon.
In addition, proportions of patients still receiving the drug at 1 year were similar for Benepali and Enbrel — 77% versus 75%, respectively — while the adjusted discontinuation hazard ratio for Benepali, compared with Enbrel, was 0.91 (95% CI, 0.83-0.99).
Regarding infliximab, the proportion of patients still on the drug at 1 year was 67% for Remicade, compared with 66% for Remsima/Inflectra, while the discontinuation hazard ratio for the biosimilar, versus the originator, was 1.16 (95% CI 1.02-1.33).
Among those who switch from an originator to one of its biosimilars, there were no statistically significant or clinically relevant differences in drug survival, compared with those who remained with the reference product.
“In our large study, there was no evidence of any clinically relevant differences in treatment retention,” Di Giuseppe said. “Neither were there any signals of poorer retention following a non-medical switch, including the lack of any obvious nocebo effect. Our results support the equivalence of biosimilars and originator products across the available marketed products.”