How do you manage pre-existing neutralizing antibodies (NAbs) in large animal populations for AAV studies?

We implement a rigorous pre-screening protocol to identify and exclude animals with high-titer pre-existing NAbs to the specific AAV serotype used in the study. This ensures that the observed toxicology and efficacy data are a direct result of the investigational product, not confounded by pre-existing immunity, a known variable in large animal populations.

What is your approach to immunosuppression protocols to mitigate anti-drug antibody (ADA) responses against AAV vectors?

Our scientific team designs prophylactic immunosuppression regimens based on established principles to delay or reduce anti-capsid antibody formation. This strategy can enhance transgene expression and provide a clearer assessment of the product’s safety profile by minimizing the impact of the host immune response to the vector itself.

For EMA submissions, what are the key differences in toxicology study design for large animal models compared to other regulatory bodies?

EMA guidance often places specific emphasis on the immunological characterization of advanced therapies. This includes detailed assessments of immunogenicity, the potential for germline transmission, and long-term biodistribution. Our study designs prospectively incorporate these endpoints to meet EMA expectations for a comprehensive risk assessment.

How do you integrate biodistribution and toxicology endpoints within a single GxP study?

We design unified protocols where toxicology assessments are conducted in parallel with biodistribution analysis. A subset of animals from the main toxicology cohorts is designated for comprehensive non-target tissue biodistribution analysis via qPCR or other appropriate methods. This approach optimizes animal usage in alignment with the 3Rs principles and generates a cohesive dataset for regulatory submission.

Executing a successful GxP toxicology program in large animal models for cell and gene therapies requires managing the inherent biological complexities of the model and the vector. The primary challenges involve pre-existing vector immunity and treatment-emergent immunogenicity, which can obscure the true safety profile of a therapeutic candidate. A robust program proactively screens for neutralizing antibodies and incorporates scientifically justified immunomodulation strategies to generate clean, interpretable data for EMA submission. This approach provides High-Fidelity In Vivo Intelligence for Complex Modalities.

A significant variable in AAV gene therapy development is the host immune response. Large animal species can possess pre-existing neutralizing antibodies to common AAV serotypes due to natural exposure.

As demonstrated in foundational research, these NAbs can effectively block vector transduction in vivo, confounding study outcomes and reducing the translational relevance of the data (PMID: 26067568). An effective toxicology program begins with rigorous NAb screening to establish immunologically naive cohorts, ensuring that the observed safety and biodistribution data are directly attributable to the therapeutic article.

Beyond pre-existing immunity, the development of anti-drug antibodies post-administration presents another challenge. A proactive strategy involves the use of transient, prophylactic immunosuppression to mitigate the immune response against the vector capsid.

This approach is supported by studies showing that specific immunosuppressive regimens can delay anti-capsid antibody development and improve transgene expression (PMID: 37833563). By controlling for immune-mediated clearance of the vector, we can more accurately assess the intrinsic toxicology profile of the product, a key requirement for regulatory review.

Our GxP-compliant programs are executed within a >100,000 sq ft facility designed for complex biologic studies. We specialize in integrated study designs that combine toxicology, biodistribution, and immunogenicity endpoints into a single, efficient protocol. This methodology streamlines development, supporting a typical 18-24 month IND timeline. Since 2019, programs developed with our scientific leadership have achieved a 100% IND success rate, with the Franklin Biolabs brand itself launching in 2024.

Our programs are designed to meet or exceed global standards, conducted in compliance with USDA regulations and in collaboration with AAALAC-accredited partners.

Our approach is built upon the core principles of the 3Rs:

• Reduce: Using advanced statistical analysis and integrated study designs to minimize the number of animals required.

• Refine: Employing sophisticated techniques and environmental enrichment to enhance animal well-being.

• Replace: Continuously evaluating and validating alternative methods where scientifically appropriate.