Proven Intelligence Accelerating Next-Generation Therapies.

Executive Summary

Residual host cell proteins (HCPs) present a known risk to viral vector product quality, potentially impacting immunogenicity and overall safety profiles. Standard immunoassays like ELISA are limited to detecting a predefined subset of HCPs, leaving a substantial portion of the proteome uncharacterized. Franklin Biolabs employs liquid chromatography with tandem mass spectrometry (LC-MS/MS) to provide comprehensive, unbiased identification and quantification of HCPs in AAV, lentivirus, and adenovirus preparations, directly supporting robust CMC packages for IND submissions. This approach minimizes clinical risk by providing a complete inventory of process-related impurities.

The Analytical Challenge of Process-Related Impurities

The purity of a viral vector preparation is a foundational quality attribute. During production, proteins from the host cell system can co-purify with the final product. These residual HCPs can be immunogenic, potentially eliciting an unwanted immune response that could neutralize the therapeutic vector or cause adverse events.

Characterizing the immune response to vector components is a well-established field. Work defining T cell epitopes in viral proteins (PMID: 15823604) and evaluating the immunogenicity of different adenoviral vector platforms (PMID: 29093095) underscores the sensitivity of the immune system to foreign proteins. These biological insights directly inform the level of analytical rigor required during manufacturing: any protein impurity could act as an adjuvant, confounding the product’s intended safety and efficacy profile.

Limitations of Traditional Immunoassays

For years, the industry standard for HCP quantification has been the enzyme-linked immunosorbent assay (ELISA). While useful, this method has inherent limitations:

• Coverage: A process-specific ELISA is only as effective as the polyclonal antibodies it employs. It cannot detect HCPs to which no antibodies were generated.

• Bias: The assay provides a single, aggregated value (e.g., ng of HCP per dose) and cannot identify which specific proteins are present.

• Process Changes: Any significant change in the upstream or downstream manufacturing process may alter the HCP profile, potentially requiring a costly and time-consuming re-development of the ELISA.

Unbiased Proteomics for Complete Characterization

LC-MS/MS-based proteomics overcomes the limitations of traditional methods. By directly analyzing the proteins present in a sample, this technique provides an unambiguous and comprehensive view of process impurities.

The workflow involves enzymatic digestion of all proteins in the sample, separation of the resulting peptides by liquid chromatography, and their subsequent identification and quantification by high-resolution mass spectrometry. This allows for the identification of hundreds to thousands of individual HCPs, providing actionable intelligence to manufacturing teams for process optimization. This level of detail is invaluable for demonstrating process consistency and product purity to regulatory bodies.

Our >100,000 sq ft facility is equipped to perform these complex analytical assays under GxP conditions, supporting programs from preclinical development through IND submission. This capability has been a component of the work contributing to a 100% successful IND rate for programs conducted since 2019, with the Franklin Biolabs brand itself launching in 2024 to carry this legacy forward.