No differences in adverse events, including infusion-related reactions, infections, and hypogammaglobulinemia, were reported among patients receiving rituximab and the biosimilar, CT-P10.
The first rituximab biosimilar approved in Europe, CT-P10, was proven to be a safe alternative to the reference drug, according to a study published in Springer.1 Findings are reinforced by evidence on interchangeability and switching to biosimilars in real-life settings, which will aid clinicians in their decision-making process.
“The cost of CT-P10 is 60–70% lower than rituximab, providing a significant financial incentive to switch to the use of biosimilars, allowing more patients to access life-saving treatment,” a team of Turkish investigators wrote. “One of the problems in biosimilar products including CT-P10 is immunogenicity, which is a major safety issue. It might result in fatal complications by causing unwanted immune responses, which in rare cases, occur as anaphylaxis or hypersensitivity reactions in patients.”
With this in mind, to accept biosimilars as an interchangeable option, comparison studies should emphasize that switching between the biologic originator and the biosimilar does not affect either safety or efficacy.2
A retrospective review analyzed treatment-related adverse events in patients treated with 1 or more dose of originator rituximab or CT-P10 between September 2020 and December 2021 who had at least 6 months of follow-up after a rituximab infusion in a rheumatology clinic. Adverse events included infusion-related reactions (IRRs), infections, and hypogammaglobulinemia. Additional data, including demographics, concomitant disease-modifying antirheumatic drugs (DMARDs) use, prior use of DMARDs, and disease duration were collected.
Switching between rituximab and the biosimilar was conducted based on drug availability at the hospital pharmacy at the time of infusion and followed the local hospital’s procedures. Clinicians were not involved in the biosimilar selection decision.
A total of 128 patients were included in the study, of which 64 received CT-P10 and 64 were treated with rituximab. Of these patients, 40.6% (n = 52) switched to CT-P10 and 35.5% (n = 48) continued rituximab treatment. The mean age was 53 years and most (n = 93) patients were female. Baseline demographics were comparable between groups, except for age.
No difference in IRRs, the most common adverse events, were reported among patients receiving CT-P10 and rituximab (25 vs 30, respectively) and all reactions were rated as graded 1 and 2. Similarly, no significant differences were reported in rates of infections (P >0.05) and rate of hypogammaglobulinemia (P >0.05).
The most common IRRs were laryngeal paresthesia, tightness in the chest, and drowsiness/weakness. Infections were reported in 33.9% (n = 19) of patients in the CT-P10 cohort and 35.0% (n = 21) in the rituximab cohort, with upper respiratory tract and urinary tract reported as the most frequently reported infections. Patients who developed IRRs were more likely to be female (P = 0.018) and had a longer disease duration (P = 0.004); however, they were not deemed significant after multivariate analysis. The risk of developing IRRs was comparable among treatment groups.
The retrospective nature of the study may have limited the results. Additionally, subgroup analysis by rheumatological diseases could not be conducted due to the heterogeneous population. The single-center study design may have limited the generalizability of the findings. However, this was the largest study to demonstrate a comparable safety profile between rituximab and CT-P10 in patients with rheumatic disease in a real-world setting.
“Given the value of cost/effectiveness, the use of biosimilars may result in reduced treatment costs, thereby increasing patients’ access to rituximab treatment and providing economic benefits for healthcare systems,” investigators concluded.