Navigating Host Cell Protein (HCP) ELISA Bridging Challenges During Customer Process Tech Transfer

By Oktawia Borkowska
Principal Scientist, Analytical Development

Scientist Spotlight: Oktawia Borkowska, Principal Scientist, Analytical Development. Navigating Host cell protein (HCP) ELISA bridging challenges during customer process tech transfer

Bringing complex therapeutic molecules to the market involves many stringent regulatory assessments that can also vary over time; yet the characterization of the product substance as well as the relevant impurities remain one of the key aspects of all successful clinical trial and license applications. With current trends seeing the intrinsic complexity and heterogeneity of these molecules increasing, an even bigger burden is placed on analytics, requiring cutting edge instrumentation and characterization techniques.

At Lonza, I work in a team that specializes in the comprehensive analysis of complex biopharmaceuticals. We employ cutting edge mass spectrometry techniques to unravel structural and functional intricacies of each molecule that comes to the characterization team. Within my role I leverage my extensive method development and characterization experience to oversee and guide the development, manufacturing as well as testing of the drug substance to support our customers with a successful clinical trial or license application.

One of the challenges faced in the biopharmaceutical development is the characterization of product and process related impurities. As stated in ICH Q6B guideline this needs to be done to the extent possible therefore Lonza continues to invest in the latest technologies and develops new workflows to make these complex analyses faster to support our customers.

Host cell proteins (HCPs) are a critical process related impurities that require monitoring during biopharmaceutical process to ensure product purity and most importantly, patient safety. Enzyme-linked immunosorbent assay (ELISA) is the workhorse method for monitoring HCPs due to its sensitivity, specificity and throughput.

A requirement for a license application is to show the HCP ELISA is fit for purpose, and this is done through method validation and HCP coverage assessment. At Lonza we like to start evaluating this as early as possible so it’s ready for process validation. If a customer is using the Lonza platform upstream manufacturing process they will be using the Lonza platform HCP ELISA, but if a customer is not, they sometimes leverage a commercially available kit.

Important to note: When approaching the strategy for HCP ELISA to support process validation, there are a lot of things to consider. If a customer comes to us with a commercial ELISA, it is not always best to switch during the late clinical phase of the product.

For one specific example, a customer came to Lonza with their manufacturing process using a commercially available HCP ELISA method. Using traditional coverage assessment referenced in USP 1132 we compared HCP coverage of the commercially available ELISA kit and the Lonza HCP ELISA method. Lonza HCP ELISA had higher HCP coverage and looked to be better than the commercially available kit for process validation and BLA.

In addition to the above, we now leverage orthogonal mass spectrometry testing to de-risk the HCP bridging to the new ELISA and show that it is fit for purpose. Due to the lineage of the cell line, the use of Lonza platform ELISA was deemed the best path forward for a project as this mitigates the need to generate a process specific ELISA reagent.

As part of the analytical technology transfer process we generated data on the historical batches where it was identified that the overall HCP value increased with the Lonza HCP ELISA method. This raised concerns within the project team and it was decided to utilize Lonza’s HCP MS method to support the HCP bridging. As part of any method bridging, the historical batch data is used to support the new specification setting and in Lonza’s experience health authorities are unlikely to accept an increase in HCP levels without sound scientific justification. The data package which includes HCP reagent coverage assessment as well as orthogonal LC-MS/MS testing can be used to support and justify the new specifications. Every situation is always slightly different, we actively discuss every scenario with customers in order to agree on the best option for the project.

Figure 1: Schematic of Lonza’s HCP MS method to support the HCP bridging

Technology transfers are a significant part of the development and commercialization process for biopharmaceutical products.

At Lonza we recognize this and have a tailored approach to ensure a seamless analytical method transfer which supports customers’ product success. As discussed here, often one of the biggest challenges from an analytical perspective is host cell protein control and measurement. HCP is an obligatory Critical Quality Attribute (CQA) due to safety and because of this we have an orthogonal approach leveraging both ELISA and orthogonal mass spectrometry technologies to de-risk the transfer as much as possible.