A phase 3 study of rituximab biosimilar HLX01 in patients with diffuse large B-cell lymphoma

Rituximab in combination with chemotherapy has shown efficacy in patients with diffuse large B-cell lymphoma (DLBCL) for more than 15 years. HLX01 was developed as the rituximab biosimilar following a stepwise approach to demonstrate biosimilarity in analytical, pre-clinical, and clinical investigations to reference rituximab. With demonstrated pharmacokinetic similarity, a phase 3 multi-center, randomized, parallel, double-blind study (HLX01-NHL03) was subsequently conducted to compare efficacy and safety between HLX01 plus cyclophosphamide, doxorubicin, vincristine, and prednisone (H-CHOP) and reference rituximab plus CHOP (R-CHOP) in a total of 407 treatment-naïve, CD20-positive DLBCL patients aged 18-80 years. The primary efficacy endpoint was best overall response rate (ORR) within six cycles of treatment in the per-protocol set (PPS). Secondary endpoints included 1-year efficacy outcomes, safety, and immunogenicity profile. The results showed difference in ORRs [H-CHOP 94.1%; R-CHOP 92.8%] between two treatment groups was 1.4% (95% confidence interval [CI], - 3.59 to 6.32, p = 0.608) which falls within the pre-defined equivalence margin of ± 12%. The safety profile was comparable between the treatment groups, with a similar overall incidence of treatment-emergent adverse events (H-CHOP 99.5%, R-CHOP 99.0%, p = 1.000) and serious adverse events (H-CHOP 34.0%, R-CHOP 32.5%, p = 0.752). This study established bioequivalence in efficacy and safety between HLX01 and reference rituximab. The trial was registered at http://www.chinadrugtrials.org.cn on 26 August 2015 [#CTR20150583].