Treatment of immune thrombotic thrombocytopenic purpura (iTTP) with the rituximab biosimilar Truxima (Napp Pharmaceutical Group Ltd) yielded equivalence in ADAMTS13 recovery, platelet count at 28 days and 3 months after administration, and cluster of differentiation (CD) 19 depletion compared with MabThera (Roche Pharmaceuticals), the rituximab originator. Infusion and infective complications were also similar between the biosimilar and the originator, according to study results published in the British Journal of Haematology.
Rituximab is an immunosuppressive drug that can be used to treat iTTP. Expiration of the patent for MabThera resulted in an influx of approved biosimilars for the treatment of different diseases. Because of bioequivalence in pharmacokinetics and immunogenicity, Truxima has been approved for all indications for which MabThera is approved in Europe and South Korea.
Immunosuppression with CD20 antibodies forms the backbone of therapy for iTTP. Autoantibodies for ADAMTS13 mediate iTTP.
In this study, researchers examined outcomes from 84 consecutive patients with iTTP over 2 years. Patients were treated with MabThera for 12 months before switching to treatment with Truxima.
Platelet counts were not significantly different between acute MabThera and Truxima therapy at day 1 (D1), day 28 (D28), or 3 months after treatment initiation (D1, P =.085; D28, P =.77; 3 months, P =.71). Platelet counts also were not significantly different between elective MabThera and Truxima therapy (D1, P =.79; D28, P =.68; 3 months, P =.99).
Additionally, ADAMTS13 recovery was not significantly different acutely (D1, P =.99; D28, P =.27; 3 months, P =.26) or electively (D1, P =.59; D28, P =.61; 3 months, P =.34).
Percent depletions of CD19 at D1 and 3 months were not significantly different between the biosimilar and the originator acutely (D1, P =.52; 3 months, P =.56) or electively (D1, P =.22; 3 months, P =.19).
Infusion reactions and infective complications both had similar incidences in the 2 rituximab treatment groups.
The authors concluded that because the efficacy demonstrated by this rituximab biosimilar was comparable to the efficacy of the originator, “more patients [should be able] to receive this therapy, given the cost effectiveness.”
1. Stubbs MJ, Low R, McGuckin S, et al. Comparison of rituximab originator (MabThera) to biosimilar (Truxima) in patients with immune-mediated thrombotic thrombocytopenic purpura [published online March 28, 2019]. Br J Haematol. doi:10.1111/bjh.15874