Celltrion's Rituximab Biosimilar Demonstrates Equivalence in Follicular Lymphoma

Investigators said they were able to demonstrate the biosimilarity of a rituximab biosimilar (CT-P10 [Truxima]) to reference rituximab in a long-term (27 months) efficacy and safety study (N = 258) involving a single transition from the originator to the biosimilar in patients with low–tumor burden follicular lymphoma (LTBFL). CT-P10 is a Celltrion biosimilar that was approved by the FDA in November 2018 for patients with CD20-positive, B-cell non-Hodgkin lymphoma.

The trial was a randomized (1:1), controlled, double-blind, phase 3 study in LTBFL. Patients received CT-P10 (375 mg/m²) weekly or the reference product at the same dose for an induction period of 4 cycles, followed by maintenance treatment once every 2 months for 2 years. The primary end point was overall response rate (ORR) over 7 months, defined as the number of patients achieving complete response (CR), unconfirmed complete response, or partial response. The secondary end point was ORR during the study period, overall survival (OS), progression-free survival (PFS), and time to progression.

Most patients completed induction and initiated maintenance period 1 (CT-P10, n = 123; reference, n = 120). Reasons for treatment discontinuation were similar between treatment groups, with the most frequently reported reason in both groups being progressive disease.

Investigators reported no clinically meaningful differences in ORR or OS between treatment cohorts over the study period. The ORR was 88% (n = 115) in the CT-P10 cohort and 87% (n = 111) in the rituximab reference group. This included CR rates of 56% and 52% for the CT-P10 and rituximab reference groups, respectively.

Median PFS was not estimable in either group due to a low number of events. The investigators stressed caution in interpreting the significance of this “due to the relatively immature data set.” There was no difference in OS between groups, although median OS also was not estimable.

The investigators said 88% and 81% of patients in the CT-P10 and reference groups, respectively, experienced at least 1 treatment emergent adverse event, and 11% of patients in each group experienced treatment emergent serious adverse events. “There were no unexpected safety signals … after the single transition from rituximab [reference] to CT-P10,” said Larry W. Kwak, MD, PhD, lead author, City of Hope, Duarte, California.

“The overall similarity in ORR, OS, and safety over the study period supports the biosimilarity between the CT-P10 and rituximab [products]," Kwak said, adding that longer-term follow-up is needed to understand the efficacy findings.

Reference

Kwak LW, Sancho JM, Cho SG, et al. Long-term efficacy and safety (27 months) of the biosimilar CT-P10 in patients with low tumor burden follicular lymphoma. Presented at: 62nd American Society of Hematology Annual Meeting and Exposition; December 5-8, 2020. Poster 1125. https://ash.confex.com/ash/2020/webprogram/Paper135999.html