TOPLINE

Rituximab biosimilars achieved remission in a notable proportion of patients with antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) by 6 months, with no significant differences compared to the originator. No relapses occurred in patients who switched from originator to biosimilar maintenance therapy.

METHODOLOGY

• An observational study enrolled 207 adults with granulomatosis with polyangiitis (GPA) or microscopic polyangiitis from nine Canadian centers between July 2021 and September 2023; participants had started rituximab treatment as early as 2018.
• Mean age at cohort entry was 56.7 years, 52% were women, 80% were White, and 70% had GPA; median disease duration was 1.6 years.
• Participants included 132 starting rituximab induction (58 originator and 74 biosimilar), 59 starting maintenance (23 originator and 36 biosimilar), and 16 switching from originator to biosimilar maintenance.
• This study focused on remission at 6 months, defined as Birmingham Vasculitis Activity Score version 3 of 0, a prespecified endpoint; other outcomes assessed included relapse, change in Vasculitis Damage Index, and serious adverse events (SAEs).
• Rituximab-pvvr was the most commonly used biosimilar.

TAKEAWAY

• At 6 months, 51 of 53 (96%) participants in the originator induction group and 66 of 73 (90%) in the biosimilar induction group achieved remission (difference 6%; 95% CI, −4% to 15%).
• At 3 months, 48 of 51 (94%) in the originator group and 57 of 72 (79%) in the biosimilar group were in remission (difference 15%; 95% CI, 2% to 26%).
• One minor relapse occurred in each induction group and in the originator maintenance subgroup (remission re-achieved by 6 months); all participants in the maintenance and switch groups remained in remission at 6 months.
• SAEs occurred in 8% of originator induction, 14% of biosimilar induction, 9% of originator maintenance, 6% of biosimilar maintenance, and 19% of switch group participants, with no significant differences in event rates between originator and biosimilar subgroups.

IN PRACTICE

"The present study provides unique real-world evidence of the rituximab originator compared to the biosimilar in AAV, comprehensively evaluating vasculitis control, damage, SAEs including serious infections, and drug access," wrote the authors of the study.

SOURCE

The study was led by Arielle Mendel, MD, MSc, McGill University in Montreal, Quebec, Canada. It was published online July 30 in ACR Open Rheumatology.

LIMITATIONS

Differences in participant selection between originator and biosimilar groups could introduce bias. The small sample sizes of maintenance subgroups limited statistical power for meaningful comparisons. The relatively short 6-month follow-up period and rarity of early relapses restricted the ability to detect differences in relapse rates.

DISCLOSURES

The study was supported by the Canadian Initiative for Outcomes in Rheumatology cAre. One author's work was supported by a Fonds de Recherche Quebec Santé salary award. Several authors reported financial relationships — including grants, consulting fees, speaker honoraria, advisory board participation, expert testimony, and travel support — with multiple pharmaceutical companies.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.