Towards a Platform Chromatography Purification Process for Adeno-Associated Virus (AAV)

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Bogdanovic, A., Donohue, N., Glennon, B., McDonnell, S. and Whelan, J., 2025. Towards a Platform Chromatography Purification Process for Adeno‐Associated Virus (AAV). Biotechnology Journal, 20(1), p.e202400526. 

This peer-reviewed study explores how chromatography can form the basis of a scalable, serotype-independent AAV purification platform. While AAV serotypes vary in surface structure, they often share key characteristics such as size, density, and isoelectric point. Yet current purification approaches typically remain serotype-specific.

The authors propose that by focusing on these commonalities, we can streamline purification and build a more standardized and efficient gene therapy manufacturing process.

This work provides a scientific and strategic foundation for transforming AAV purification from bespoke workflows into scalable, universal platforms—advancing the reliability, accessibility, and impact of gene therapies.

The Challenge of Impurity Management in AAV Production

The production of AAV vectors typically generates various impurities that can compromise the safety and efficacy of the final therapeutic product. The authors classify these impurities into two main categories: process-related and product-related:

• Process-related impurities include host cell DNA/RNA, host cell proteins (HCPs), plasmid DNA, and media components.

• Product-related impurities include empty capsids, replication-competent AAV particles, and aggregated or degraded vectors.

These impurities must be characterized and reduced to acceptable ranges, aligning with Good Manufacturing Practices (GMP) and regulatory guidelines.

However, controlling and eliminating certain product-related impurities, such as empty capsids, remains particularly challenging due to their similarity to full capsids in physical properties. The authors highlight that downstream processing (DSP) must account for these intricacies during chromatography platform development.  

Lessons from Monoclonal Antibodies (mAb) Production

The authors draw parallels between the development of AAV purification processes and the well-established platform for monoclonal antibodies (mAbs). The success of the mAb platform is attributed to its universal design heuristics, such as prioritizing complicated separations at the end of the process, removing high-quantity impurities early, and addressing unstable materials swiftly.

These "rules of thumb" can inspire the development of a similar platform for AAV, albeit with modifications to address AAV-specific challenges. 

Critically, tools like high-throughput process development (HTPD) and response surface modeling (RSM) are cited as promising methods for accelerating AAV platform creation:

• High-throughput process development (HTPD): for rapid resin and condition screening.

• Response surface modeling (RSM): for exploring interactions between variables like pH and conductivity.

Together, these approaches could streamline the exploration of the design space for AAV purification while minimizing experimental workload. 

Chromatography and the Quest for a Universal Platform

Chromatography is central to current AAV purification efforts, with multiple types of resins and monoliths trialed for their ability to capture or separate impurities. The authors offer insights into some of the most promising materials for a platform approach, such as POROS CaptureSelect AAVX and CIMmultus monoliths, which demonstrate serotype-agnostic capabilities in AAV binding and impurity removal.

In contrast, certain resins, like AVB Sepharose, which binds only specific serotypes, may limit their application in a universal process. 

Moreover, intermediate and polishing steps employ specialized resins, such as CaptoQ ImpRes and Superdex 200, which enable the separation of full AAV capsids from empty or aggregated ones.

Together, these technologies—when combined with a deeper understanding of how AAVs interact with chromatography media—form a strong foundation for building a scalable, serotype-independent purification platform.

Toward a GMP-Ready Solution

The authors stress that the increasing demand for gene therapies using recombinant AAVs (rAAVs) necessitates the rapid establishment of a GMP-ready platform process. By standardizing purification methods, this platform would facilitate faster adoption of AAV therapies while reducing costs and complexity at the process development stage.

However, significant challenges remain, including the diversity of AAV serotypes and the limited experience in large-scale AAV manufacturing within the biopharmaceutical industry.

In summary, the authors provide a robust roadmap for the development of an AAV chromatography-based purification platform. By integrating insights from mAb production, leveraging high-throughput tools, and optimizing chromatography materials for AAV-specific properties, the path forward is clear.

The implementation of such a platform could unlock the full therapeutic potential of AAV vectors, paving the way for more accessible and effective gene therapies to patients in need. 

Bogdanovic, A., Donohue, N., Glennon, B., McDonnell, S. and Whelan, J., 2025. Towards a Platform Chromatography Purification Process for Adeno‐Associated Virus (AAV). Biotechnology Journal, 20(1), p.e202400526.