From The Editor | January 29, 2025

GlycoNex On Challenges In Biosimilar Development, Manufacturing

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By Tyler Menichiello, contributing editor

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Biosimilars are integral to a healthy biotech market. While their developers face many of the same manufacturing challenges as novel biologics (e.g., optimizing process development and scaling), biosimilar development has its own unique challenges. Perhaps most notable among these are the stringent analytical requirements, which need to demonstrate comparability to reference products, and the market pressure to reduce manufacturing costs. To gain further insight into the challenges biosimilar developers face, I conducted a written Q&A with the president and CEO of GlycoNex, Dr. Mei-Chun Yang. Her responses have been edited for style and clarity.

Dr. Mei-Chun Yang, President & CEO, GlycoNex
What challenges has GlycoNex faced in the development of its denosumab biosimilar, SPD8?

  • Structural Complexity: The complexity of denosumab’s IgG2 structure presents significant scientific and technical challenges. IgG2 antibodies display unique disulfide isomerization patterns, which result in structural heterogeneity. The isomers — IgG2-A, IgG2-B, and IgG2-A/B — affect stability, binding affinity, and functionality. Ensuring consistent disulfide isomer distribution is essential to achieve equivalence with the reference product.
  • Patent Issues: Originator companies typically secure multiple process patents that cover various aspects of production, including media composition, upstream processes, purification methods, and formulation techniques. As biosimilar developers, we must navigate these patents by identifying alternative approaches to achieve comparable product quality while avoiding infringement. However, it is nearly impossible to uncover all process patents held by originators.

What challenges does GlycoNex face currently?

The main challenge is lowering manufacturing costs, as denosumab (Prolia and Xgeva) is already priced relatively low. While biosimilars aim to offer cost savings, high development and production expenses limit manufacturers' ability to reduce prices. This is further complicated by denosumab's low starting price, making cost reductions even harder to achieve. GlycoNex has managed to reduce manufacturing costs by optimizing feed strategies to maximize productivity. We are also working to increase batch sizes to distribute fixed costs across more products.

What are the keys to ensuring product similarity during biosimilar process development (i.e., similarity to the reference product)?

  • Establishing Robust Analytical Methods: It is important to develop precise comparability testing to align the biosimilar's critical quality attributes (CQAs) with the reference product.
  • Verify Functionality: We use cell-based assays to confirm the biosimilar's activity and functionality.
  • Ensure Consistent Quality: It is critical to implement effective parameter controls to maintain consistent product quality throughout production.  

What kind of process analytical technologies (PAT) does GlycoNex rely on to ensure GMP process control and consistent product quality?

  • UV-Vis Spectroscopy: To measure protein concentration and purity
  • High-Performance Liquid Chromatography (HPLC): To evaluate glycosylation profiles, aggregates, and degradation products
  • Capillary Electrophoresis-Sodium Dodecyl Sulfate (CE-SDS): Provides high-resolution separation of protein variants and impurities
  • Mass Spectrometry (MS): To identify post-translational modifications and ensure the molecular profile aligns with the reference product
  • Real-Time Sensors And Offline Measurements: To monitor critical process parameters (CPPs) like pH, dissolved oxygen, dissolved carbon dioxide, glucose levels, and lactate levels in bioreactors

How does GlycoNex prepare for and execute the scaling of its manufacturing processes for biosimilars throughout development?

The process begins with the selection of stable, high-productivity clones, integrating process development early in clone selection to ensure scalability. Critical process parameters (CPPs) are optimized using Design of Experiments (DoE) in systems such as Amber-250 to establish a robust foundation. Pilot-scale testing in 1 L bioreactors is conducted to refine culture conditions and assess scalability. Incremental scaling through larger bioreactors, including 50 L systems, validates process reproducibility and robustness under production-like conditions. Robust analytical methods are implemented early to ensure consistent monitoring of product quality throughout development and scaling.

At the commercial scale, 2,000 L validation runs are conducted to confirm process consistency and reliability under full-scale manufacturing conditions. These runs include real-time monitoring of key parameters, such as pH, dissolved oxygen, temperature, and nutrient feed rates, to ensure precise control and alignment with CPPs. Extensive product quality assessments are carried out during and after these runs, ensuring CQAs such as glycosylation, purity, and yield meet predefined specifications. This structured and rigorous approach ensures the delivery of high-quality biosimilars that comply with regulatory standards and meet commercial production demands.

Can you elaborate on GlycoNex’s approach to high-productivity cell line development? What are the company’s key principles for developing a stable, high-productivity cell line?

The keys for developing a stable, high-productivity cell line include:

  •  Host-cell cloning to select a clone with a desirable growth profile
  • A proprietary expression vector with an optimized factor combination
  • A high-throughput screening system
  • An optimized culture process

Please explain the importance of glycosylation control in your company’s biosimilar development process. How can this affect safety and efficacy?

Although the primary mechanism of action (MoA) of SPD8 is to block RANKL function with minimal impact from glycosylation, GlycoNex remains committed to ensuring that the N-glycan profile of SPD8 closely matches that of the reference biologic to maintain safety and avoid immunogenicity.

What are the most significant ways GlycoNex is advancing its biosimilar development platform, whether through new technologies, adopting continuous manufacturing processes, etc.?

GlycoNex creates a seamless workflow from cell line selection to manufacturing by combining CQA-driven clone selection with integrated process development. This approach reduces time and resources while ensuring high similarity to the reference biologic and minimizing risks during scale-up.

  • CQA-Driven Clone Selection: GlycoNex incorporates CQA analysis early in cell-line development to identify clones capable of producing highly similar products with optimal growth and productivity. By prioritizing clones aligned with CQAs, GlycoNex reduces the risk of deviations during later stages.
  • Integrated Process Development: Process development considerations are embedded into the clone selection phase to streamline scale-up and simplify optimization. Clones are pre-adapted to process conditions, minimizing the need for extensive adjustments later.
  • Scalable Clone Identification: The early identification of scalable clones ensures a smooth transition to larger bioreactors.