|Eculizumab is a humanized monoclonal antibody targeting terminal complement activation, by binding to complement component C5 and inhibiting the production of C5a . It is the first approved therapy for paroxysmal nocturnal hemoglobinuria.
Eculizumab's developers, Alexion Pharmaceuticals have developed a next-generation version of eculizumab called ravulizumab (ALXN1210; FDA approved in December 2018), that has a longer circulating half-life than the originator, which allows for monthly dosing.
The evidence confirming C5, C5a and the C5a receptor as anti-inflammatory and anti-cancer drug targets is reviewed by Horiuchi and Tsukamoto (2016) .
ABP 959 (Amgen) is in Phase 3 development under the jurisdiction of the Australian New Zealand Clinical Trials Registry (trial ID ACTRN12616000509460).
BOW080 (Epirus Biopharmaceuticals) is in preclinical development- see
None of these biosimilars can be FDA approved until Alexion's exclusivity period (due to protection as an orphan drug) expires in March 2019. Eculizumab's patent protection ends in May 2020 (Europe) and March 2021 (US). Hence, Alexion developed the improved agent ravulizumab as a replacement product.