Gene therapy AAV Approach
Gene therapy researchers have found modified viruses to be effective vehicles (“vectors”) for introducing therapeutic genes into cells. Adeno-associated viruses (AAV) play a unique role here and represent the most commonly used approach: most gene therapy vectors deliver therapeutic genes by integrating their genetic material into the DNA of the host cell, whereas episomal AAV-delivered genes are expressed transiently and do not permanently modify the genetic information of the cells. This results in very low immunogenicity and practically zero oncogenic potential. Hence, AAV-derived active substances are becoming the vector of choice for delivering gene therapies for a vast number of diseases; they have been investigated for the treatment of cancer as well as ocular, pancreatic and CNS conditions.
The fundamental benefit of using AAV particles as the primary “delivery system” for gene therapeutics is based in its favorable safety profile. AAV cannot replicate its genetic information without additional help by specific plasmids not present in the cells of the patient, which means it will not propagate in the body like other viruses. The genetic information introduced by AAV particles thus eventually disappears, which gives physicians precise control over how much AAV is administered. For these reasons, AAV is driving today’s therapeutic discoveries and has become the dominant form of gene therapy for genetic diseases. At the same time, regulatory demands are increasing, as authorities request extensive analytical characterization for the drug vectors (e.g. capsid loading, process impurities). This requires reliable, robust, GMP-compliant analytical methods and characterization protocols, and specific analytical assays need to be performed to assess vector productivity, vector purity, biological activity and safety.
PPS offers a broad range of analytical methods for measuring the strength/dose of the AAV vector, quantifying full/empty particles and illegitimate encapsulated DNA, and ensuring the identity, purity, potency and safety of the final product. Verifying whether the gene of interest is actually present in the vector is essential for monitoring the production process as well as for evaluating the right dosage for the patient. PPS uses the following techniques to determine vector loading:
- Analytical ultra centrifugation (AUC)
- SEC-MALLS, AF4-MALLS
- cGE, AEX
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