Disulfide bond reduction has been a challenging issue in antibody
manufacturing, as it leads to reduced product purity, failed product
specifications and more importantly, impacting drug safety and efficacy.
Scientists across industry have been examining the root causes and
developing mitigation strategies to address the challenge. In recent
years, with the development of high-titer mammalian cell culture
processes to meet the rapidly growing demand for antibody
biopharmaceuticals, disulfide bond reduction has been observed more
frequently. Thus, it is necessary to continue evolving the disulfide
reduction mitigation strategy and development of novel approaches to
achieve high product quality. Additionally, in recent years as more
complex molecules emerge such as bispecific and trispecific antibodies,
the molecular heterogeneity due to incomplete formation of the
interchain disulfide bonds becomes a more imperative issue. Given the
disulfide reduction challenges that our industry are facing, in this
review, we provide a comprehensive contemporary scientific insight into
the root cause analysis of disulfide reduction during process
development of antibody therapeutics, mitigation strategies and recovery
based on our expertise in commercial and clinical manufacturing of
biologics. First, this paper intended to highlight different aspects of
the root cause for disulfide reduction. Secondly, to provide a broader
understanding of the disulfide bond reduction in downstream process,
this paper discussed disulfide bond reduction impact to product
stability and process performance, analytical methods for detection and
characterization, process control strategies and their manufacturing
implementation. In addition, brief perspectives on development of future
mitigation strategies will also be reviewed, including platform
alignment, mitigation strategy application for bi- and tri-specific
antibodies and using machine learning to identify molecule
susceptibility of disulfide bond reduction. The data in this review are
originated from both the published papers and our internal development
work.