Real-World Data Underscore the Safety and Highlight the Acceptance of Biosimilar Rituximab

While no biosimilar rituximab products have yet become available in the United States, despite the recent approval of Celltrion and Teva’s Truxima, biosimilar rituximab products are available in the European Union, and data on their use, published concurrently with the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting, highlight not only their safety but also their growing acceptance among prescribers in Europe.

First, researchers reported interim safety results from a real-world study of Sandoz’s biosimilar rituximab, Rixathon, as curative therapy for CD20-positive diffuse large B-cell lymphoma (DLBCL).¹ The study, REFLECT, is the first post-approval study of the biosimilar in DLBCL.

REFLECT includes adult patients with DLBCL who are eligible for treatment with rituximab and cyclophosphamide, doxorubicin, vincristine, prednisone, or R-CHOP. The study’s primary end point is complete response rate at the end of treatment.

In an interim analysis, with a cutoff of September 2018 and with approximately 50% enrollment, the full analysis set comprised 80 patients. In total, 53 adverse events (AEs) were reported, and 13 were deemed to be treatment-related. There were 19 serious AEs, 2 of which were deemed to be treatment-related. Six AEs led to discontinuation, 6 led to dose interruption, and none led to death.

These interim data from this ongoing study, say the investigators, are as expected for rituximab-based treatment.

Also published alongside the ASCO meeting were data concerning the prescribing of biosimilar rituximab in the European Union.²

The study used data from the Ipsos Global Oncology Monitor, which provided deidentified data on 3239 patients with non-Hodgkin lymphoma treated with anticancer drugs in France, Germany, Italy, Spain, and the United Kingdom between 2017 and 2019. Data on patients treated with and without a rituximab biosimilar were compared using descriptive statistics.

While the prescribing of the reference rituximab was stable during the study period, the prescribing of biosimilar rituximab increased significantly, from 7% to 35% (P <.01). The uptake of the biosimilar was particularly strong in Germany and the United Kingdom; by the third quarter of 2019, for those patients who had rituximab prescribed as part of a regimen, prescribing of a biosimilar was 72% in Germany and 63% in the United Kingdom.

Additionally, physicians were more likely in 2018 than in 2017 to state “proven efficacy” and “well tolerated” as their reasons for prescribing the biosimilar.

France, Italy, and Spain had 47%, 32%, and 30% rates of biosimilar prescribing, respectively, which the study suggests may be driven by skepticism about subsequent-entry products that has been observed with generics in some European countries.

Prescribing of the brand-name rituximab may also be driven, in part, by the availability of a subcutaneously administered formulation, which is not available for biosimilar versions at this time, the study author noted.

References

1. Welslau M, Marschner N, Wolff T, et al. Sandoz rituximab (GP2013; SDZ-RTX) for the treatment of diffuse large B-cell lymphoma (DLBCL): interim safety results of the non-interventional, observational, multicenter, open-label REFLECT study. Presented at: American Society of Clinical Oncology Annual Meeting 2019; May 31-June 4, 2019; Chicago, Illinois. Abstract e19020.

2. Francescetti A. NHL and rituximab biosimilar: How have prescribing behaviours changed in EU5 in 15 months? Presented at: American Society of Clinical Oncology Annual Meeting 2019; May 31-June 4, 2019; Chicago, Illinois. Abstract e19054.