Real-world Data Show Interchangeability of Rituximab Biosimilar

A retrospective real-world study assessing patient outcomes related to switching from reference rituximab (Rituxan) to a biosimilar version (Truxima) found that transitioning between the products was safe for patients and did not result in a change in adverse events.

A retrospective real-world study, published in Internal and Emergency Medicine, assessing patient outcomes related to switching from reference rituximab (Rituxan) to a biosimilar version (Truxima) found that transitioning between the products was safe for patients and did not result in a change in adverse events.

The study concluded that Truxima (Celltrion Healthcare), also known as CT-P10, is a safe treatment alternative for patients who require therapy with rituximab and that data on interchangeability and switching in real-life scenarios can help clinicians become more comfortable with biosimilars.

“We believe that an increased number of real-life studies on biosimilars conducted among patients with various diseases could assist healthcare providers, stakeholders, and decision makers in using biosimilar rituximab,” wrote the authors.

Rituximab is used to treat antineutrophil cytoplasmic antibody–associated vasculitis (AAV), rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE) on label and systemic lupus erythematosus, systemic sclerosis, inflammatory myopathies, Sjogren syndrome, and IgG4-related disease off label.

The authors reviewed treatment-related adverse events in patients treated with at least 1 dose of the reference product or biosimilar between September 2020 and December 2021, with at least 6 months of follow-up after rituximab infusion. The patients were treated at the University Hospitals Rheumatology Outpatient Clinic in Turkey. The study included 128 patients with a mean (SD) age of 53.0 (12.5) years. Overall, 64 patients received the biosimilars and 64 patients received the originator. Of those the received the biosimilar, 52 were switched from the originator and 12 received it on first infusion.

Of the adverse events that were reviewed, there were no statistically significant differences between the 2 treatment groups.

The most common adverse events observed were infusion-related reactions (IRRs; 55 patients [43.0%]), such as laryngeal paresthesia, chest tightness, drowsiness/weakness. Most IRRs (69.1%) occurred during the first hour after infusion. Only 14.5% of IRRs occurred during the first infusion of rituximab. There were no treatment-emergent IRRs of grade 3 or higher reported in either treatment group.

“None of the reactions reported in these studies was considered serious, all resolved without causing any problems, and most occurred after the first infusion and within the first hour of infusion,” explained the authors.

Infections were observed in 19 (33.9%) patients in the biosimilar group and 21 (35.0%) patients in the originator group (P = .903). The most frequent infections were upper respiratory tract infections and urinary tract infections. In each group, 6 patients needed to be hospitalized for their infections, and 3 of the reactions (1 in the originator group, 2 in the biosimilar group) led to COVID-19–related pneumonia, resulting in death. Five of the hospitalizations in each group were caused by COVID-19–related pneumonia.

When attributing the reason for the infections, the authors wrote, “Considering that data were collected during the COVID-19 pandemic for this study, COVID-19–pneumonia could have an impact on higher occurrence rates of infections compared to previously reported rates. Moreover, it is thought that use of high-dose glucocorticoids or a history of immunosuppressive drugs, such as cyclophosphamide may trigger the risk of infections in some patients which might explain the high incidence of infection in this study.”

The risk of developing IRRs did not differ between the patients who received the biosimilar vs the originator (odds ratio, 1.376; 95% CI, 0.68-2.78; P = .373). Patients who were most likely to develop an IRR were more often female (P = .018) and had longer disease duration (P = .004); however, these factors were not determined to be significant during the multivariate analysis (P = .099 and P = .052, respectively).

“This is the largest study that provides data on interchangeability and safety issues in heterogeneous populations with rheumatologic diseases in a post-marketing real-world setting,” the authors noted.


Bahap-Kara M, Duran E, Bayraktar-Ekincioglu A, Karadag O. Interchangeability and adverse events in originator-rituximab and its biosimilar (CT-P10) among rheumatic patients: a real-life experience. Intern Emerg Med. 2023;8(3):791-799. doi:10.1007/s11739-023-03222-x

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