Gene therapy was once an experimental technique and an object of dreams, using the concept of faulty gene replacement to reprogram the body to fix itself and cure disease. However, this is no longer a distant mirage — the future is now! There are currently 20 FDA-approved gene therapeutics on the market, allowing doctors to treat many diseases without the need for drugs or surgery. With new research coming it also seems that the future of gene therapy holds endless possibilities to cure anything from rare genetic conditions to cancer or even HIV in the not-too-distant future. For gene therapy to work, viruses, like the adeno-associated virus (AAV), are typically incorporated into the final product as the gene delivery vehicle targeting cells to replace faulty genes with healthy ones. The pipeline for new gene therapeutics is strong with the FDA expecting approvals to reach around 20 per year by 2025. In addition to this, the market — which has a current annual growth rate (CAGR) of 33.6% — is expected to increase from $3.6 billion in 2020 to $35.7 billion by 2027, making it one of, if not the most, explosive biopharma market on the planet!
Is your Capsid half-full or half-empty? It turns out only completely full will do ...
AAV vectors are common gene delivery vehicles. Empty capsids, which do not contain the gene therapy of interest, and partial capsids, those containing only a fragment of the gene of interest, are by-products of the AAV production and can impact product safety and maximum efficacy. The amount of full, partial, and empty capsids, therefore, needs to be characterized and monitored through process development. There are various methods used to characterize full, partial, and empty capsid levels, including analytical ultracentrifugation, transmission electron microscopy, charge detection mass spectrometry, and anion exchange chromatography. However, there are challenges and disadvantages with each.
Fear not, though. In this July 15 webinar titled “Emerging LC-MS Techniques to Characterize AAV at the Subunit and Intact Levels,” Anita Liu, Lead R&D Specialist and Victoria Cotham, Analytical Scientist from Regeneron will discuss a unified approach using high-resolution mass spectrometry to quantify ratios of empty, partially and fully filled capsids.
Learn about ways to analyze adeno-associated virus capsids with different MS methods
See methods developed to achieve serotype identification, PTM characterization, and stoichiometry assessment
Rapid online analytical strategies to quantify ratios of empty, partially, and fully filled capsids
So now that we know how full your capsids are, what next?
It is important to understand capsid identity because each AAV serotype has unique capsid proteins that transfer the genetic material to specific cells or organs. Depending on the therapeutic target area the correct AAV serotype is chosen, and the identity and purity are monitored. All AAV capsids consist of three proteins (VP1, VP2, and VP3) that share high-sequence homology, and ensuring the identity and purity of these proteins is critical to viral infectivity and gene transfer. Given the importance of the serotype and the capsid protein composition, there is a need for methods to identify and monitor the capsid and the capsid proteins through gene therapy development and manufacturing.
In addition to the webinar mentioned above, which discusses how to monitor AAV serotypes in detail, Professor Albert J.R. Heck, Distinguished Faculty Professor, Utrecht University, takes "A Detailed Look at Antibodies, Plasma Proteins, Viruses and Gene-Delivery Vehicles by High-Resolution Native Mass Spectrometry,” unlocking unique insights into the complexity of those biotherapeutics. Professor Heck presents:
Ways to analyze the next generation of biopharmaceutical products with different MS methods
Methods developed to analyze IgG hexamers, endogenous viruses, and adenovirus delivery vectors
Native mass spectrometry strategies for the analysis of higher molecular weight compounds