Improving AAV Production

Solving manufacturing complexities often depends on interdisciplinary expertise. Statistics suggest that over 65 percent of gene therapies in development use adeno-associated virus (AAV). However, AAV production is complex and time consuming, partly because current analytical methods mainly rely on manual sampling. Now, the Cell and Gene Therapy Catapult (CGT Catapult), in collaboration with Rentschler Biopharma and Refeyn, are hoping to change things. Here, Yatindra Tirunagari, Technical Expert at Rentschler Biopharma discuss the nature of the partnership – and what it could mean for the future of AAV manufacturing.

What sparked the collaboration?
 

Our mutual understanding of the challenges we face as an industry was a monumental factor!

And what is the main focus?
 

Ultimately, we aim to develop and apply process analytical technologies to improve AAV manufacture. Real-time monitoring and feedback control for AAV manufacturing would allow real-time decision-making, reduce processing bottlenecks, and enhance process reproducibility and batch-to-batch comparability. 

To get there, the teams will carry out high throughput and automated sampling and analysis of AAV material throughout the production process. This data will then be leveraged for the creation of digital twins: digital models of the manufacturing process that can be used to further refine and improve the efficiency of the process. 

Afterwards, we hope to use these digital models to perform initial tests of changes to the process in a digital environment, which should reduce the number of expensive and time-consuming physical tests which need to be carried out in the laboratory. This will allow us to assess for improvements in productivity and AAV yield using automated analytical technologies. For example, we can use Refeyn’s technology to assess the proportion of full AAV capsids produced. This is a key measurement for the industry, as quantity of full AAV capsids indicates process efficiency but may also impact clinical efficacy.

What are the current limitations of AAV manufacture?
 

The optimization of upstream and downstream processes depends on the ability to rapidly characterize critical quality attributes (CQAs). In the context of rAAV production, the virus titer, capsid content, and aggregation are identified as potential CQAs, affecting the potency, purity, and safety of rAAV-mediated gene therapy products. 

Analytical methods to measure these attributes commonly suffer from long turnaround times or low throughput for process development – partly because current analytical methods mainly rely on manual sampling. However, rapid, high-throughput methods are beginning to be developed and commercialized; as is also the case in the collaboration project between Rentschler Biopharma, CGT Catapult and Refeyn. These methods are not yet established in academic or industrial practice, and supportive data are scarce.

We believe active engagement across scientific disciplines (academia, industry experts and technology vendors or suppliers) will allow us to openly discuss the challenges we face, whilst creating an environment to discover solutions.

Refeyn’s technology is a key part of the partnership; why is this technique so promising?
 

Current standard practices involve analytical ultracentrifugation, electron microscopy or PCR/ELISA – each of which present drawbacks (not least long turnaround times, high sample consumption, and the need for specialized staff).

Mass photometry is a bioanalytical technique that measures the mass of AAVs in solution and at a single particle level. The analysis requires smaller amounts of sample than other techniques and takes less than five minutes. In our collaboration, Refeyn’s technology will be used to assess the proportion of full AAV capsids produced. This is a key measurement for the industry, as the quantity of full AAV capsids indicates process efficiency but may also impact clinical efficacy.