The safety of a rituximab biosimilar in Europe was highlighted in data presented in an abstract at the American Society of Clinical Oncology (ASCO) Annual Meeting (May 31 – June 4, 2019; Chicago, IL).
Currently, no rituximab biosimilar products are available in the US, despite the recent FDA approval of rituximab-abbs. However, rituximab biosimilar products are available in the European Union, and data on their use are beginning to be published.
A group of German researchers conducted the REFLECT real-world study, the first post-approval study of a rituximab biosimilar product (SDZ-RTX) in diffuse large B-cell lymphoma (DLBCL). Researchers examined the safety results of SDZ-RTX administration as a curative therapy option for CD20-positive disease.
Among 80 patients included in the study were adults who were eligible for treatment with rituximab and cyclophosphamide, doxorubicin, vincristine, prednisone, or R-CHOP. The primary endpoint of the study was complete response rate at the end of treatment, and secondary endpoints included overall response rate, progression-free survival at 12 months, and adverse events.
Data were collected at baseline and every study visit for 12 months as well as after 30 days since last SDZ-RTX dosage.
In the interim analysis—with a cutoff data of September 2018 and with almost 50% enrollment—a total of 53 adverse events were reported, 13 of which were determined to be treatment-related. The most frequent adverse events were polyneuropathy (12.5%), anemia (10%), and fatigue (10%).
Additionally, there was 19 serious adverse events, though only two of which were deemed treatment-related.
Researchers acknowledged that six adverse events led to treatment discontinuation, six adverse events led to dose interruption, and no adverse events led to death.
In their concluding comments, researchers noted that the interim baseline data are as expected for treatment-naïve patients with CD20-positive DLBCL, and the safety results are as expected for the rituximab-based treatment. The study is ongoing, they added.—Zachary Bessette