Efficacy and safety of ABP 798 compared with rituximab: Results from the comparative clinical study in patients with non-Hodgkin’s.

Abstract

8044 Background: ABP 798* is being developed as a biosimilar to rituximab, a CD20-directed cytolytic antibody. A randomized, double-blind, active-controlled study compared the efficacy, safety, and immunogenicity of ABP 798 with rituximab reference product (RP) in subjects with CD20-positive NHL; results of the final analysis are presented here. Methods: Adult subjects with grade 1, 2, or 3a follicular B-cell NHL and low tumor burden were randomized to receive intravenous ABP 798 or RP (375 mg/m2) once weekly for 4 weeks, then at weeks 12 and 20. The primary endpoint was risk difference (RD) of overall response rate (ORR) by week 28. Secondary endpoints included RD of ORR at week 12, pharmacokinetics, pharmacodynamics, safety, and immunogenicity. Results: 254/256 randomized subjects were treated with at least one infusion of ABP 798 (n = 128) or RP (n = 126); ORR by week 28, based on independent central blinded assessment of the modified full analysis set, was comparable between the ABP 798 and RP groups (78% vs. 70%, respectively). The 2-sided 90% confidence interval of RD of ORR (-1.4%; 16.8%) was within the pre-specified margin (-15%; 35.5%) thereby establishing clinical equivalence between ABP 798 and RP. This result was supported by analyses of the secondary efficacy endpoint of RD of ORR at week 12. In the two groups, the geometric least squares means for serum concentrations over time (e.g., week 12, pre-dose: ABP 798, 21.89 vs. RP, 20.57; week 12 post-dose: ABP 798, 201.30 vs. RP, 203.52) and the extent of B-cell depletion from day 1 to day 8 (ABP 798, 98.3% vs. RP, 98.3%) were similar. Frequency, type, and severity of adverse events (AEs) were comparable between ABP 798 and RP groups; grade ≥3 AEs were reported in 10.9% and 10.3% of subjects and serious AEs in 3.9% and 4.0%, respectively. Most common AEs were headache, fatigue, and nausea; the most common AE of interest was infusion reactions. No new or unexpected safety signals were observed. Binding and neutralizing anti-drug antibodies were comparable between groups. Conclusions: Results of this study demonstrated clinical similarity between ABP 798 and rituximab RP in subjects with CD20-positive NHL. *At the time of this submission, ABP 798 had not been approved by the FDA or any relevant regulatory agency and the indications are yet undetermined. Please consult ABP 798’s later approved label in the relevant country for information regarding the approved uses for ABP 798.