Aggregates and particles in therapeutic protein products: causes, characterization and control

Written in collaboration with Judy Hadley, Malvern Panalytical’s Market Development Specialist – RMM 

Numerous studies have been undertaken to understand whether aggregates can cause immunogenicity (the ability of a protein or chemical substance to provoke an immune response) since uncertainty is a high risk. Aggregation of therapeutic proteins can occur during bioprocessing, shipping, storage and even delivery to the patient. Understanding of the roles of aggregates in immunogenicity of therapeutic protein products is critical. Such immune responses can have serious consequences for patients.

While most recent studies suggest confirmation of the relationship between aggregates and immunogenicity, many questions remain, such as: whether a particular subset of particles may be the cause, what attributes need to be controlled, what amount it takes to break the threshold, and what the nature of the response is. With these questions in mind, the analytical methods have become important not only for lot release as a QC tool, but also in the research and development phases to understand what needs to be controlled in order to understand whether aggregates are immunogenic or not.

At the final fill stage of manufacturing, protein aggregation can result from several causes: shelf life, foreign particles that adhere to proteins, mechanical shock, routine handling and mishandling, agitation, compression, dilation, and pumping. Proteins adsorb onto most interfaces; for example, the tubing type selected can affect the presence of aggregate particles resulting from shedding.

In a recent webinar, Professor John Carpenter and his team at the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences did a deep dive into the causes of protein aggregates and particles present in therapeutic protein products. In his presentation, Professor Carpenter explains how it is critical to utilize the right instrumentation to detect and characterize aggregates and particles in the nanosize range and shows examples of how Nanoparticle Tracking Analysis (NTA) and Resonant Mass Measurement (RMM) have been utilized to detect the presence of particulates, which by light obscuration alone had gone undetected. Watch the webinar to learn how an approach encompassing the characterization of both the micro and nano-size ranges is key to understanding and identifying the cause of aggregates and foreign particles with an end goal of controlling particulates levels.

RMM measurements with the Archimedes instrument provides count and size data and can distinguish protein aggregates from and other materials such as silicon oil droplets which may be present in the product.

If you do not have the right toolset to detect protein aggregates, you are running of risk of immunogenicity; Malvern Panalytical’s NanoSight instrument should be in your tool set!

• WhitePaper – NTA: Protein Aggregation
• Article – ‘Critical to Quality’ measurements of protein aggregation in biopharmaceuticals
• Webinar – Aggregates and particles in therapeutic protein products: Causes, characterization and control
• Blog – John Carpenter’s keynote speech at next month’s biophysical & particle characterization symposium
• Webinar – The roles of nanoparticles in therapeutic protein aggregation pathways