Executive Summary

A well-designed GxP biodistribution study is a required component of any Investigational New Drug (IND) application for an AAV-based gene therapy targeting the central nervous system. For intrathecally administered AAVrh10 vectors, the scientific challenge is to accurately quantify vector genome persistence, transgene expression, and potential non-target tissue biodistribution. This requires a multi-faceted analytical approach, combining molecular and histological endpoints to build a comprehensive safety and efficacy profile. A successful program de-risks clinical translation, directly supporting an 18-24 month IND timeline.

The Challenge of Intrathecal AAVrh10 Delivery

Intrathecal administration provides direct access to the CNS, bypassing the blood-brain barrier. However, achieving predictable and safe vector delivery throughout the target neuroaxis is not straightforward. The specific route of administration chosen for a program can have profound implications for the safety profile.

Key translational insights from preclinical research underscore this challenge. Studies evaluating different intrathecal delivery techniques have shown that route selection can lead to significantly different safety outcomes, including inflammatory responses, despite achieving similar levels of target tissue transduction (PMID: 28806897). This highlights the need for rigorous, early-stage evaluation of the chosen delivery method to ensure the nonclinical model accurately reflects the intended clinical approach.

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Designing a GxP-Compliant Biodistribution Program

A definitive biodistribution study for an intrathecal AAVrh10 vector integrates multiple analytical platforms to generate a complete data package for regulatory submission. Our approach, conducted within our >100,000 sq ft GxP-compliant facility, is built on a foundation of validated assays and deep vector biology expertise.

• Vector Genome Quantification: Sensitive, validated qPCR assays are used to measure vector DNA copy numbers in all collected tissues, including CNS, DRGs, and peripheral organs. This provides the core quantitative data on vector persistence and dissemination.

• Transgene Expression Analysis: Histology with IHC or ISH provides cellular-level confirmation of transgene expression within target tissues. This qualitative data is vital for correlating vector presence with functional protein expression.

• Comprehensive Tissue Analysis: The study must assess both target tissue transduction and non-target tissue biodistribution. This provides the detailed data necessary to build a complete safety profile.

“We started collaborating with UPenn Vector core in 2023 and the AAV vector which they manufactured laid a foundation for development of a gene therapy candidate which will enter soon preclinical studies. The key people from UPenn Vector Core joined Franklin Biolabs and our partnership transitioned without interruption from UPenn Vecor Core to Franklin Biolabs Research Vector Division. Franklin Biolabs is our trusted partner in our AAV-vector based gene therapy candidate development and we hope to continue the partnership for years to come.”
— Biotech Partner