The eculizumab biosimilar SB12 is equivalent to eculizumab in patients with paroxysmal nocturnal hemoglobinuria (PNH), according to the results of a randomized phase 3 clinical trial published in the European Journal of Haematology. These results “support SB12 use in PNH patients,” the authors of the study said.

The double-blind, multinational crossover study compared the safety, efficacy, pharmacokinetics, and immunogenicity of SB12 and eculizumab in patients aged 18 or more years with PNH. 

Participants were randomly divided into 2 groups. Those in one group received SB12 then eculizumab, while those in the other group received eculizumab then SB12.

For the first 3 weeks, patients in the first group received 600 mg of SB12 infusions every week. This was followed by 900 mg of SB12 infusions every 2 weeks until week 26 when SB12 was switched to eculizumab. Eculizumab treatment continued until week 50 at a dose of 900 mg infusions every 2 weeks. 

Patients in the second group started with 600 mg weekly infusions of eculizumab, then 2 weekly infusions of 900 mg of eculizumab, and then were switched to 900 mg of SB12 infusions every 2 weeks until week 50.

Read more about eculizumab for the treatment of PNH

The primary endpoint was hemolysis as measured by the levels of lactate dehydrogenase at Week 26 and the secondary endpoint was hemolysis at Week 52. 

The results showed that the levels of lactate dehydrogenase in the serum of all patients were equivalent at week 26. 

The mean numbers of transfused red blood cell units, other secondary endpoints, pharmacokinetics, and pharmacodynamics were also comparable between the groups. 

None of the patients developed antidrug antibodies and the occurrence of treatment-emergent adverse events was similar between the 2 groups, at 72% in the SB12 group and 68% in the eculizumab group.

Eculizumab, marketed under the brand name Soliris®, is a recombinant humanized monoclonal antibody that specifically binds to C5 complement protein thereby inhibiting terminal complement-mediated intravascular hemolysis. It is the first drug the US Food and Drug Administration approved for the treatment of PNH.

SB12 has been developed as a biosimilar to reference eculizumab and has been shown in previous clinical trials to have equivalent pharmacokinetics and comparable pharmacodynamics, safety, and immunogenicity profiles to eculizumab.


Jang JH, Gomez RD, Bumbea H, et al. A phase III, randomised, double-blind, multi-national clinical trial comparing SB12 (proposed eculizumab biosimilar) and reference eculizumab in patients with paroxysmal nocturnal haemoglobinuria. Eur J Haematol. Published online December 20, 2022. doi:10.1002/jha2.632 

A study to compare SB12 (proposed eculizumab biosimilar) to Soliris in subjects with paroxysmal nocturnal haemoglobinuria. US National Library of Medicine. Last updated October 25, 2021. Accessed December 22, 2022.