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21 Sep 2020

TESSA technology for robust and reproducible AAV manufacture at scale

Novel, plasmid-free manufacturing system reduces the cost of goods and improves AAV quality to enable development of safer gene therapies.

OXGENE, a designer and developer of scalable gene therapy technologies, has launched its scalable, plasmid-free manufacturing system for adeno-associated virus (AAV).

AAV, is a popular choice of viral vector to deliver gene therapies to patients, owing to its low immunogenicity, favourable safety profile and the ease with which it transduces numerous cell and tissue types.

Manufacturing systems, however, have not kept pace with biological advances, leaving these therapies costly, difficult to produce at scale, and subject to inherent batch-to-batch variability, thus representing a serious challenge to regulators and health authorities with regard to approving these treatments for clinical use.

OXGENE claims its TESSA technology overcomes manufacturing obstacles by taking advantage of AAV’s natural relationship with another virus — the adenovirus. In nature, AAV co-exists with adenovirus, which provides the ‘help’ AAV needs to replicate.

Yet, as well as replicating the AAV, the adenovirus also replicates itself, leading to high levels of adenoviral contamination if this process is translated to an industrial context.

OXGENE says it is confident it has addressed these challenges by manipulating the adenoviral life cycle so that it can still provide high quality help for AAV replication, but is unable to manufacture itself, reducing adenoviral contamination by 99.99% in a manufacturing run.

Integration of the AAV rep and cap genes into the adenoviral vector means that everything required for AAV production, except the AAV genome, can be provided in a single viral vector.

Meanwhile, the AAV genome can either be encoded within a second TESSA vector, in a plasmid, or within an AAV particle itself. Using two TESSA vectors improves yields of AAV2 by 40-fold, accompanied by a 2000-fold increase in particle infectivity compared to a standard three-plasmid manufacturing approach.

Once this first AAV seed stock has been produced, co-infecting cells with this AAV alongside another TESSA vector can further amplify the AAV in a simple, reproducible and scalable manner, removing the reliance on expensive and limiting plasmids for AAV manufacture.

According to OXGENE’s CEO, Dr Ryan Cawood, the gene therapy industry’s reliance on plasmids is a "major limitation for robust and reproducible large-scale AAV manufacture".

He commented: "By taking a ‘back to nature’ approach to rethink AAV production from the ground up, we’ve developed a truly innovative technology that we expect to transform the way AAV is manufactured.

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