Abstract
Complement activation is known to be one of the recognized toxic effects of a class of oligonucleotide therapeutics. For many phosphonothioate antisense oligonucleotides, complement activation occurs due to drug interactions with Factor H in the alternate pathway of the complement activation pathway, and species differences in its effects have been reported. Complement activation is likely to occur in monkeys, whereas complement activation is rarely observed in other species. In this study, we conducted a method development and validation study of an in vitro complement activation assessment system that may be useful in considering human relevance for complement activation found in cynomolgus monkeys during oligonucleotide drug development.
One negative control or three positive control oligonucleotide solutions were each mixed at a constant ratio with cryopreserved serum collected from cynomolgus monkeys and healthy adult volunteers incubated at 37℃ for 1 hour, and serum C3a, Bb and C5a were determined. Negative control oligonucleotide did not increase complement levels in cynomolgus monkeys or humans. All complements were elevated in cynomolgus monkeys after exposure to 3 positive control oligonucleotides. In humans, exposure to 2 positive control oligonucleotides led to slight increases in C3a and Bb, and exposure to 3 positive control oligonucleotides led to slight increases in C5a. The magnitude of the increase in complement in in vitro was clearly higher in cynomolgus monkeys than in humans, which may recapitulate the previously reported differences in the strength of complement activation. These findings suggest that in vitro complement assessment system established here is a system that can be used to discuss species differences in complement activation by oligonucleotide drugs and human relevance.
