How early in process development should you address glycosylation? This episode presents the case for co-optimizing glycan profiles with productivity from initial process characterization. Deferring glycosylation characterization until after titer targets are met introduces risk: quality attribute gaps discovered late in development force process re-optimization, extended timelines, and potential cell line reselection. Media supplementation enables earlier intervention—tuning glycan distribution as a process parameter from the beginning of cell line and media development rather than as a remediation strategy.

David Brühlmann outlines the experimental protocol for validating raffinose supplementation, including decision criteria for proceeding or terminating at each development stage. The discussion addresses process design space requirements, analytical monitoring strategy, and the experimental variables that determine when media-based glycan tuning is appropriate versus when alternative approaches are needed.

Highlights from the episode:

• When to use (and not use) raffinose in your development program, including limitations and effectiveness windows (00:30)
• Essential protocol: three experiments over eight weeks to validate raffinose for your process, with clear go/no-go criteria (04:09)
• Why individualized mannose tracking (Man5, Man6, Man7, Man8) is crucial for meaningful results (01:06)
• Managing osmolality: why it matters and how to control it in your experiment (04:36)
• Advice on scaling up: moving from small-scale screens to benchtop bioreactors and stress-testing your process (07:48)
• Three key mistakes to avoid when implementing raffinose, including lessons from analytical oversight, incomplete design mapping, and feed interference (09:08)
• Integrating glycosylation as a core part of process design, not just a secondary consideration after titer optimization (13:10)

Strategic insight:

Sequential optimization of productivity followed by glycosylation introduces development risk: quality attribute deviations discovered after process lockdown require costly re-optimization cycles. Parallel development of titer and glycan specifications from initial cell line characterization reduces this risk by establishing feasible operating windows early in the development timeline.

Are you planning your next recombinant protein scale-up? Hear how David’s rule-of-three protocol and battle-tested lessons can help you optimize faster and avoid painful late-stage surprises.

Resources: Journal of Biotechnology, 2017, volume 252, pages 32 to 42

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