BEBPA’s 7th annual Host Cell Protein Conference May 15-17th took place in Los Angeles, California. It once again attracted HCP experts from biopharma, service- and technology providers, and regulatory agencies.
The organizing committee had again put together a great mix of talks, workshops and round-table discussions. Very importantly, there was also plenty of time for questions and networking. We even got a chance to share HCP-challenges between competing companies, which you seldom see at conferences.
My colleague Rikke Lund and I have made a short summary of key topics and take‐home messages from the meeting, for those who could not attend:
Main Topics at BEBPA 2019
- Mass Spectrometry Data Analysis Methods for HCP Analysis
- Improved Methods for HCP Antibody Coverage
- Safety and Tox Risks of Host Cell Protein Impurities
- Health Authority Panel Discussion
Mass Spectrometry Data Analysis Methods
Most, if not all, presentations at the conference included mass spectrometry (MS) analysis of HCPs at different levels. It was said more than once that Mass Spectrometry is becoming a standard method. This goes for both characterization and control of process-related impurities.
The MS Workshop, on day one, discussed software and challenges for both Data Dependent Analysis (DDA) and Data Independent Analysis (DIA) workflows.
Some points discussed at the BEBPA HCP workshop:
- Different workflows and search engines impact the HCP identifications. Consistent results are obtained when at least 2 unique peptides are required for a positive identification.
- False Discovery Rates (FDR) are based on statistics and are thus only meaningful to apply when a certain number of peptides are observed. FDR are not relevant at the protein level when only a few HCPs are present in a purified drug substance.
- Absolute, reproducible HCP quantification can be obtained with DIA workflow using intact proteins as internal standards.
- As mass spectrometry moves into more regulated HCP analysis software improvements are therefore needed for; better manual QC check of data, higher reproducibility, ease-of-use and reportability.
Improved Methods for HCP Antibody Coverage
A common problem with 2D PAGE Western Blots is that they often show too few proteins in the low Mw-region. So this may indicate that small proteins are not covered in the ELISA.
A detailed study found that this is due to multiple issues, including; low amounts of antibodies for low Mw proteins, and also low protein amounts on blots.
Alphalyse presented a new HCP Coverage method using plate-based immunocapture in the ELISA plate and LC-MS/MS identification of the captured proteins.
The immunocapture LC-MS method provides a detailed list of host cell proteins covered by the ELISA. It also provides an HCP Coverage percentage and a Specific Coverage of HCPs in the drug substance.
Safety and Tox Risks of Host Cell Protein Impurities
The Risk Assessment Workshop, multiple presentations and roundtable discussions clearly show the importance of this topic. The HCP risk evaluation can thus further be divided into; Safety/Efficacy risk for the Patient, and Process and Product risk for the biopharma company.
The BioPhorum Development Group – A Multi-Company Collaboration presented their views on “High Risk” Host Cell Proteins, and establishment of lists of potentially problematic HCPs.
The work has focussed on HCPs from CHO, and will be expanded to other expression cell lines, e.g. E. coli. The BioPhorum Development Group plans to make the work and lists of proteins publicly available.
Health Authority Panel Discussion
On the last day of the conference, the regulatory representatives from FDA and EMA each gave their personal perspectives. Below you will find some key points from their slides.
Biopharma are advised to:
- develop an HCP control strategy
- introduce an HCP assay early in the development process
- characterize the HCP profile
- establish assay capabilities (coverage and range, etc.)
- develop process specific assay if commercial assay is insufficient
- develop bioanalytical assay for anti-HCP antibodies in patient plasma samples in parallel with assay for HCPs in the product
- re-qualify the assay following major changes in the manufacturing process
The chosen HCP assays should have:
- high sensitivity and be able to detect low levels of HCPs expected in the product
- high specificity and also perform well in the presence of large amount of therapeutic protein
- sufficient coverage and demonstrate the ability to detect the majority of the HCPs present in the final product
- demonstrated quantitative relationship to the amount of HCPs in the final product
Overall, we came back from the well-organized BEBPA 2019 HCP Conference with a lot more knowledge about HCP impurity control, and many new contacts within the existing field. We will certainly return for BEBPA HCP Conference in 2020.
Rikke Lund and Ejvind Mørtz, Alphalyse