Pharmacokinetic and Safety of CT-P10, a Biosimilar Candidate to the Rituximab Reference Product, in Patients with Newly Diagnosed Advanced Stage Follicular Lymphoma (AFL)

Background: CT-P10 is a biosimilar candidate to the reference rituximab product, EU-approved MabThera^® and US-licensed Rituxan^®. CT-P10 has an identical amino acid sequence and highly similar physicochemical and in vitro functional properties to its reference drug. In patients with rheumatoid arthritis, CT-P10 has demonstrated compelling similarity in pharmacokinetics (PK), pharmacodynamics (PD), efficacy, safety and immunogenicity (Yoo DH, et al. Arthritis Rheum. 2013;65(10):1736).

Objective: The goal of this study was to demonstrate PK similarity of CT-P10 to rituximab, each administered in combination with cyclophosphamide, vincristine, and prednisone (CVP) in patients with newly diagnosed Advanced Follicular Lymphoma (AFL) (NCT02162771) (Kim WS et al. Blood. 2015;126(23): 5111). The results of PK, PD, safety and immunogenicity up to Core Cycle 4 (12 weeks) are presented here from this ongoing study.

Methods: Patients with AFL were randomized 1:1 to receive infusion (375mg/m²) of either CT-P10 or rituximab, at a 3-week interval, in combination with CVP. PK analysis was conducted in terms of AUC_tau and C_max at steady state, Core Cycle 4, as primary PK endpoints. PK parameter values considered as outliers determined by robust regression outlier testing were excluded from the pharmacokinetic primary analysis.

Results: In total, 121 patients were randomly assigned to receive either CT-P10 (n=59) or rituximab (n=62) in combination with CVP. Result of CT-P10 PK at Core Cycle 4 was similar to that of rituximab. The ratios (90% CI) of geometric least square means (CT-P10 to rituximab treatment group) were 102.3% (94.1%-111.2%) for AUC_tau and 100.7% (93.8%-108.0%) for C_maxSS at Core Cycle 4. The 90% CIs of ratio of geometric LS means for both AUC_tau and C_maxSS were entirely contained within the equivalence margin of 80% to 125% (Table 1 and Figure 1). Mean serum concentrations of the study drug were highly similar for the 2 treatment groups at each time point (Core Cycle 1 to 4).

The B-cell kinetics was similar up to Core Cycle 4 in the 2 treatment groups. Median number of B-cells decreased to below the lower limit of quantification (LLoQ) (20 cells/μL) 1 hour after the end of infusion at Core Cycle 1 and remained below the LLoQ at each subsequent cycle, up to and including Core Cycle 4.

The proportion of patients with a positive anti-drug antibody up to Core Cycle 4 at post-treatment visits was similar between the 2 treatment groups; 3/59 (5.1%) patients and 2/62 (3.2%) patients in the CT-P10 and rituximab groups, respectively.

In addition, CT-P10 was well tolerated and the safety profile of CT-P10 up to Core Cycle 4 was similar to that of rituximab. The number of patients who experienced at least 1 treatment emergent adverse event (TEAE) was 43 (72.9%) patients and 41 (66.1%) patients in CT-P10 and rituximab treatment groups, respectively. The proportion of patients who experienced at least 1 treatment emergent serious adverse event considered by the investigator to be related to the study treatment was similar between the 2 treatment groups; 2/59 (3.4%) patients and 2/62 (3.2%) patients in the CT-P10 and rituximab groups, respectively. The frequencies of adverse events special interest (AESI) were similar between the 2 treatment groups (Table 2).

Conclusion: This study demonstrated similarity of PK in terms of AUC_tau and C_maxSS between CT-P10 and rituximab in AFL patients. The B-cell kinetics and immunogenicity were comparable between the two treatment groups. CT-P10 was well tolerated with a safety profile comparable to that of rituximab up to and including Core Cycle 4 (12 weeks).

Table 1

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Statistical Analysis of Rituximab Pharmacokinetic Primary Endpoints for Core Cycle 4 at Steady State: Pharmacokinetic Population

Table 1

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Statistical Analysis of Rituximab Pharmacokinetic Primary Endpoints for Core Cycle 4 at Steady State: Pharmacokinetic Population

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Figure 1

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Mean (±SD) Serum Concentration of Rituximab Versus Time for Cycle 4 at Steady State (Linear Scale): Pharmacokinetic Population

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Mean (±SD) Serum Concentration of Rituximab Versus Time for Cycle 4 at Steady State (Linear Scale): Pharmacokinetic Population

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Table 2

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The Incidence Rates of Adverse Events Special Interest: Safety Population

Table 2

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The Incidence Rates of Adverse Events Special Interest: Safety Population

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