Efficacy and safety of rituximab biosimilar in refractory lupus

Aims To characterise patients with refractory SLE receiving rituximab biosimilar (CT-P10) and to explore short-term efficacy and safety associated with rituximab biosimilar use. Methods We retrospectively analysed data from the medical records of patients with refractory SLE who received CT-P10 in Ramathibodi Hospital, Mahidol University, Thailand. Baseline characteristics, disease activity (modified Systemic Lupus Erythematosus Disease Activity Index (SLEDAI)), response to treatment at 6 months after CT-P10 and infection over 6 months were recorded. Results Thirty-two patients with SLE received CT-P10 from April 2018 to June 2019. Of these, 29 (90.6%) were female and the mean±SD age was 36.8±15.2 years. The median (IQR) disease duration was 9.5 (1.3–13.0) years. All patients received glucocorticoid treatment and used 1.7±0.1 immunosuppressive agents at baseline, excluding antimalarial drugs. Baseline Systemic Lupus International Collaborating Clinics Damage Index score was 0.5 (0.0–1.0). Overall response, which was defined as a reduction in the modified SLEDAI score of ≥4, was achieved in 25.0% of patients at 6 months. The modified SLEDAI score reduced from 4 (1.3–8.0) at baseline to 1 (0.0–5.8) at 6 months (p=0.005). Response by active organ involvement was 71.8%. Serious infection occurred in four patients (12.5%), resulting in one death. The median time of onset of infection after CT-P10 infusion was 35.5 (17.0–72.5) days. Conclusion Rituximab biosimilar is associated with improvement in active organ involvement in patients with refractory SLE. Infection occurred early after rituximab biosimilar infusion.