SAAVE: preciSion AAV thErapy

Adeno-Associated Virus (AAV)-based viral vectors are the most prevalent modality for personalized in vivo gene therapy, with eight approved therapies. Their ability to mediate long-term gene expression without chromosomal integration ensures a relatively benign safety profile. AAV’s capsid serotype largely determines the tropism of currently used AAV vectors. The inherent lack of strong tissue selectivity leads to extremely high clinical doses required to transduce their target cells and unspecific delivery to non-target organs, such as the liver. Thus, improvements in tissue targeting are highly desired for broad therapeutic applications.

Recently, a complete retargeting was demonstrated by integrating monoclonal antibody (mAb) fragments recognizing cell-specific receptors into AAV capsids (Olarewaju et al., 2024, Mol Ther Methods Clin Dev 32 (4):101378), thereby improving their selectivity. Retargeting can be achieved by genetic fusion, where the targeting moiety is attached during AAV production, or by subsequent coupling of the targeting molecule to the purified AAV. In any case, achieving and understanding the right degree of modification optimal for efficacy and safety remains a significant challenge. Therefore, manufacturing, analysis, and control of these improved AAV vectors are currently major hurdles toapplication.

We will revisit and improve manufacturing methods for targeted AAV capsids, which are retargeted to specific cell types utilizing suitable targeting moieties, such as mAbs. Based on known and well-understood capsid variants and targeting moieties, we will evaluate different manufacturing methods for optimal yield, quality, and consistency. Finally, analytical techniques to determine the efficiency of modification and the quality and functionality of the resulting viral vectors will be tested and developed to ensure the safety and efficacy of these novel, precise therapeutics. The anticipated project duration is three years.

We are searching for an additional partner to cover the aspects of one or several of these fields: complex analytics like MS, in vivo pre-clinical systems, structural modeling, and epitope prediction. The following three entities are involved in the consortium:

IGB: Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, Department of Virus-based Technologies, Stuttgart, Germany, and Biberach, Baden-Württemberg, Germany; non-profit research institute.

Boehringer Ingelheim Pharma GmbH, Biberach, Baden-Württemberg, Germany; profit company.

UAB: Laboratory of Cell Engineering and Bioprocesses, Group of Bioprocess Engineering and Applied Biocatalysis, Escola d’Enginyeria, Universitat Autònoma de Barcelona, Catalunya, Spain. Public University

The consortium partners have the following resources and infrastructure: Developing virus-based therapies, including virus engineering, virus analytics, and process development, is a key competence that has been well established for many years. Standard and advanced equipment exists for these virus-associated activities: molecular techniques, virus quantification methods, bioreactors, and chromatography devices.