Gene therapy products while a relatively new category with limited approval history nevertheless still requires rigorous characterization and quality control. Potency estimation for gene therapy, especially those using adeno-associated virus (AAV) as a vector to deliver the product is a measure of the therapeutic activity of the drug that also involves measure infection of target cells (DNA, copy number), transcription (RNA measurement), translation (protein expression), protein modifications, proper localization of the protein product (protein function at the targeted location).
The Food and Drug Administration (FDA) describes potency for a gene therapy product as “the specific ability or capacity of the product, as indicated by appropriate laboratory tests or by adequately controlled clinical data obtained through the administration of the product in the manner intended, to effect a given result.” (21 CFR 600.3(s)). Applied StemCell (ASC) offers a preclinical Bioservice platform that support AAV gene therapy and cell therapy development to meet the fast-growing needs in gene and cell therapy space. ASC has extensive experience in AAV gene therapy products using AAV2, AAV5, AAV, 6, AAV8, AAV100M and other serotypes: titer estimation, infectivity, and potency; serotype assessment for cell line and animal models.
ASC will develop assays to determine recombinant AAV (rAAV) vector infectivity and transcription at mRNA and protein level. The conversion of the single stranded rAAV genome to a double stranded DNA for further transcription is a rate limiting step for the AAV-based therapy. ASC will combine reverse transcription and real-time PCR (TR-qPCR) method to detect the relative mRNA abundance of target genes in cell line and mouse model-derived samples and set acceptable range of RNA extraction and detection efficiency. We can also develop assays to estimate protein expression of the gene therapy product using ELISA and Western blot assays specific to the transgene being investigated.