Evaluation of a novel cyclic olefin polymer container system for cryopreservation of adeno-associated virus

Abstract

Background & Aim One of the most effective vehicles for delivery of therapeutic nucleic acids are viral vectors, demonstrated by their utility in many commercial cell and gene therapies. Despite success, gaps remain in the optimization of viral vector storage. Traditional polypropylene snap- and screw-cap vials used in academic and research settings do not have the closure integrity or inert properties required for storage of a commercial drug product. Further, glass vials commonly used for protein biologic drug products have not been fully characterized in the context of viral vectors, which have a need for colder storage temperatures and an associated need for increased break resistance. In the present work, two vial types used for biologic drug product storage, cyclic olefin polymer (COP) and glass, were evaluated for preservation of adeno-associated virus (AAV) during low-temperature storage. Methods, Results & Conclusion Preservation of AAV was evaluated using an AAV2 serotype GFP expression vector that was stored frozen at -80°C in either COP or glass vials. Different storage volumes were investigated in both vial types to determine if surface area-to-volume ratio would have any effect on viral recovery. A quantitative viral titer assay was used to measure any loss of nucleic acid content during the freeze-thaw process and HEK293 transduction efficiency was evaluated as a functional readout using flow cytometry. Overall, viral recovery was greater for larger volume samples, indicating that surface area-to-volume ratio of the storage container may be an important consideration during viral gene therapy formulation. Further, AAV recovery was greater after storage in COP as compared to storage in glass. The results provide baseline data indicating that the storage container used for a viral vector therapy can affect product quality, and that the COP vial may serve as a preferred container for commercial viral vector storage.