New data suggests that switching between rituximab biosimilars does not increase the risk of adverse events in patients with hematological malignancies. The study, published in Cancers, examined the safety of switching between different rituximab products, including biosimilars, in a real-world setting across multiple Italian centers. The findings could alleviate concerns about the safety and usage of biosimilars, potentially leading to reduced treatment costs and increased access to therapy.
The study included 505 patients with oncohematological diseases, such as non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL), from 13 centers across 8 Italian regions between March 2018 and June 2022. Researchers collected data on adverse drug reactions related to rituximab, whether it was the reference product (Rituxan) or one of its biosimilars. The analysis included both intravenous and subcutaneous formulations of rituximab, as well as intravenous formulations of the biosimilars.
Clinical information, concomitant medications, previous lines of treatment, number of prior rituximab cycles, and quality of life data were gathered. Clinical evaluations were conducted three months after the administration of rituximab biosimilars and approximately 4 to 6 months after the initial evaluation, with follow-up data collected until February 2023. The primary outcomes measured were the proportion of patients experiencing at least one adverse reaction (AR) and those experiencing at least one grade 3 or higher AR.
Of the 505 patients included, a total of 3681 infusions were administered, with 77% being biosimilars, 19% rituximab subcutaneous, and 3% rituximab intravenous. Approximately 78% of patients did not experience any switching, while 22% did. The study identified two main types of switches: switching to rituximab subcutaneous and switching among different intravenous rituximab treatments.
Adverse Reactions Analysis
Overall, 16.8% of patients reported adverse reactions (ARs). These events were more frequent in patients with indolent NHL compared to those with highly malignant NHL and CLL. Adverse reactions were significantly associated with age at diagnosis and higher neutrophil count. Of the 124 reported events (approximately 1.5 per patient), 16% were classified as grades 3 to 5. The most commonly reported events included general disorders and administration site conditions.
Interestingly, the incidence of adverse reactions was higher among patients who did not switch medications (20.7%) compared to those who did switch (3.5%). Events were reported most frequently during the first and second infusions.
Implications of the Findings
The introduction of biosimilars has been estimated to reduce treatment costs while increasing access to therapy. Rituximab, a monoclonal antibody targeting the CD20 protein found on B cells, is a crucial targeted cancer medication for certain types of lymphoma and leukemia. There are currently three rituximab biosimilars available in the US market: rituximab-abbs (Truxima), rituximab-pvvr (Ruxience), and rituximab-arrx (Riabni). Data from 2019 to 2021 showed that the overall use of rituximab decreased by more than half, while biosimilar use increased to approximately 60%.
This study provides further evidence supporting the safety of switching between rituximab products, including biosimilars. The findings suggest that concerns about increased adverse events due to switching are not substantiated by real-world clinical data. This could encourage greater adoption of biosimilars, leading to cost savings and improved access to essential cancer treatments.
