Phase 1 studies comparing safety, tolerability, pharmacokinetics and pharmacodynamics of HLX01 (a rituximab biosimilar) to reference rituximab in Chinese patients with CD20-positive B-cell lymphoma

Objective: This study aimed to compare the pharmacokinetic, pharmacodynamic and safety profiles of HLX01 (a rituximab biosimilar) and reference rituximab sourced from China (MabThera^®; rituximab-CN).

Methods: Here we report the results of two phase 1 studies. In the phase 1a, open-label, dose-escalation study (NCT03218072, CTR20140400), eligible patients received 250, 375 and 500 mg/m² HLX01 sequentially at 7-day intervals, after confirming no dose-limiting toxicity (DLT). In the phase 1b, double-blind study (NCT02584920, CTR20140764), eligible patients were given a single dose of 375 mg/m² HLX01 or rituximab-CN. The primary endpoints included safety and tolerability parameters for the phase 1a and the area under the plasma concentration-time curve from time zero to day 91 (AUC_{0-91 d}) for the phase 1b study. Equivalence was concluded if 90% confidence interval (90% CI) for the geometric least squares mean ratio (GLSMR) fell in the pre-specified equivalence criteria (80%-125%).

Results: Between June 20, 2014 and January 5, 2015, 12 patients were enrolled in the phase 1a study. The pharmacokinetics of HLX01 showed dose proportionality and accumulation to steady state. HLX01 was well tolerated, with no serious adverse events (AEs), discontinuations or DLTs. Between November 8, 2014 and August 13, 2015, 87 eligible patients were enrolled in the phase 1b study, including 43 who received HLX01 and 44 who were treated with rituximab-CN. The equivalence endpoint was met with GLSMR for AUC_{0-91 d} being 89.6% (90% CI: 80.4%-99.8%). AEs, anti-drug antibodies, and CD19+ and CD20+ B lymphocyte counts were similar between the HLX01 and rituximab-CN treatment groups.

Conclusions: Treatment with HLX01 was safe and well tolerated in Chinese patients with B-cell lymphoma. HLX01 and rituximab-CN have similar pharmacokinetic, pharmacodynamic and safety profiles.