Safety of switching between rituximab biosimilars in cancer

In more than 10 years of clinical experience, no substantial clinical and safety differences have been detected among biosimilars and their already approved biologicals [1]. However, concerns are raised with respect to the practice of switching in patients already treated with a specific biological product (either reference or biosimilar) [2].

Although there are multiple contributing factors [3], the slow uptake of biosimilars is likely due in part to the fact that patients and healthcare professionals have at times been subjected to incomplete information about biosimilars [4].

The equivalence between reference rituximab (MabThera) and its biosimilars has been demonstrated in randomized, double-blind, controlled trials [5-8].

In order to build patient and physician confidence, haematologists and pharmacists from Italy carried out a prospective observational study at the Trento General Hospital in Italy [9]. The study documented any adverse event (AE) reported in association with the use of the rituximab biosimilars Truxima (Mundipharma) and Rixathon (Sandoz) and with the practice of switching between different products in patients with non-Hodgkin’s lymphoma (NHL) and chronic lymphocytic leukaemia (CLL).

A total of 83 patients (72 NHL and 11 CLL) received rituximab and were included in the study between March 2018 and March 2019. The study population received 465 rituximab infusions, and all received biosimilars. Fifty patients (60%) experienced at least one switch between different biosimilars or between rituximab originator and biosimilar, whereas 33 (40%) received one of the two biosimilars and one patient received reference rituximab. A total of 146 AEs were reported in 71 patients (84.5%) during the study period. The AEs reported were similar in terms of seriousness and frequency, regardless of rituximab formulation and switching.

Data from post-marketing studies and real-world experience are needed to provide additional information to supplement the strong evidence already obtained on biosimilars from randomized controlled trials.

The increasing availability of biosimilars has led to significant healthcare savings and has provided greater patient access to high-cost therapeutics [10].

A cost-analysis study conducted in Europe, predicted that switching to a rituximab biosimilar would save Euros 56.82 million over a year [11].

The authors concluded that ‘in the setting of our haematology unit of a general hospital, this shared approach has increased clinicians and patients confidence in biosimilars with respect to safety, generating at the same time a 45% reduction in the price of rituximab (around 400,000 euros savings in one year)’.

Conflict of interest
The authors of the research paper [9] declared that there was no conflict of interest.

Abstracted by Silvana AM Urru, Hospital Pharmacy Unit, Trento General Hospital, Autonomous Province of Trento, Trento, Italy and the School of Hospital Pharmacy, University of Sassari, Sassari, Italy.

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