Outcomes of Rituximab-abbs versus Rituximab in Patients with Diffuse Large B-Cell Lymphoma in a Noninferiority Study.

Background: Rituximab with cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) is one of the first line treatments for diffuse large B-cell lymphoma (DLBCL). Rituximab comprises most of the treatment cost for this regimen; therefore, biosimilars, such as rituximab-abbs are crucial to provide affordable care. Although rituximab-abbs was studied primarily in follicular lymphoma, the Food and Drug Administration (FDA) approved this drug for all indications of the reference product on the basis of extrapolation. Effectiveness and safety data surrounding the use of rituximab-abbs in DLBCL is lacking.

Objective: To evaluate the effectiveness and safety of rituximab-abbs and reference product rituximab as R-CHOP treatment for patients with DLBCL.

Patients and methods: This noninferiority (NI) study compared the 2-year overall survival (OS), overall response rate (ORR), and incidence of adverse events (AEs) between rituximab-abbs and its reference product (RP) in R-CHOP among adult patients with newly diagnosed DLBCL. The study inclusion period was from 1 January 2019 to 31 December 2020. Analyses were performed on the basis of a noninferiority lower limit of 10% for OS and ORR, and an upper limit of 10% for serious AEs.

Results: There were 240 patients who received RP rituximab, while 295 patients received rituximab-abbs. The cohort had a mean age of 63.7±12.2 years and 43% were female. The 2-year OS was 81.0% and 79.6% (NI p < 0.01) while the ORR was 80.0% and 69.6% (NI p < 0.01), among the rituximab-abbs and rituximab groups, respectively. The incidence of infusion reaction AEs (NI p < 0.01) and noninfusion reaction AEs (NI p < 0.01) also met noninferiority.

Conclusions: We demonstrated that rituximab-abbs was noninferior to rituximab in both effectiveness and safety among patients receiving R-CHOP for DLBCL in this study. Long-term follow-up would be needed to confirm these results.