How effective and safe is rituximab biosimilar HLX01 in patients with moderate to severe rheumatoid arthritis?

This study evaluated the effectiveness and safety of rituximab (Rituxan) biosimilar HLX01 combined with methotrexate (MTX; Trexall) in patients with moderate to severe rheumatoid arthritis (RA) following inadequate responses to MTX. The study showed that HLX01 added to MTX resulted in improvements compared to placebo in these patients.

RA is a chronic disease that causes painful joints, joint stiffness, impaired physical activity, and decreased quality of life. Several treatment options are available for RA. One option is a csDMARD known as MTX. MTX is usually the first line of therapy for RA. However, many patients experience inadequate responses to it.

Rituximab is a biologic DMARD. It has been approved for use in the US and Europe in combination with methotrexate for adults with RA. Rituximab has not yet been approved for treating RA in China.

HLX01 is rituximab biosimilar. HLX01 is highly similar but not identical to rituximab in structure. HLX01 has been approved as the first rituximab biosimilar for the treatment of certain types of cancer in China. However, there is a need to evaluate its therapeutic potential for other diseases such as moderate to severe RA.

This study included 275 Chinese patients with moderate to severe RA and inadequate responses to methotrexate. 183 patients were randomly assigned to receive HLX01 1000mg in addition to MTX (group 1). 92 patients were randomized to receive a placebo in addition to MTX (group 2). Disease activity was evaluated using the ACR20 response rate (a 20% or higher improvement in RA symptoms) at week 24. The safety and effectiveness of HLX01 were assessed up to week 48.

At week 24, a significantly greater proportion of patients in group 1 (60.7%) achieved the ACR20 response compared to those in group 2 (35.9%). These patients also had better disease activity measures. Patients in group 1 were 2.8 times more likely to achieve an ACR20 response compared to those in group 2. Patients in group 1 also reported better pain, physical function, and mental status compared to group 2. 

After 24 weeks, 83% of group 1 and 80.4% of group 2 experienced side effects. Most side effects were mild and were mainly related to intravenous administration.

The study suggested that HLX01 improved RA disease activity and was safe in Chinese patients with moderate to severe RA after inadequate responses with methotrexate.

This study only included Chinese patients and future studies with diverse ethnicities are needed. This study was funded by Shanghai Henlius Biotech, the manufacturer of HLX01.