A Platform Production Process for Manufacturing Viral Vector and Vaccine Therapeutics Using Vero Cells

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Yang ZhiYan Zhi, program design technical lead, Fujifilm Diosynth Biotechnologies

Fujifilm Diosynth Biotechnologies (FDB) is a world-leading contract development and manufacturing organization (CDMO) with over 25 years of experience using biologicals and more than 310 projects including six licenses. Production sites are located in North Carolina and Texas. In Texas, the flexible biomanufacturing facility can handle production from preclinical to current good manufacturing practices (CGMP) commercial manufacturing. Facilities and capabilities include state-of-the-art process development; mobile cleanroom (MCR) technology with fully segregated and self-contained units that can be connected as needed for upstream, recovery, and downstream; nearly exclusive use of single-use technology; fully functional process and analytical development, including virology sections; an extensive quality system; and high-speed robotic viral product fill-in-place that will be up and running by late 2018. Texas FDB specializes in development and manufacture of viral vaccines and gene therapy treatments.

FDB facility’s solution for scale-up is to develop a viral vector platform using a popular cell line for making vaccines and gene therapy medicines: the Vero cell line derived from African green monkeys. There are currently at least five Food and Drug Administration (FDA)–approved vaccines (rotavirus, Dengue, smallpox, rabies, and polio) that are produced using Vero cells. These cells grow well in adherent serum–containing culture, so scaling up is challenging.

In phase 1 FDB will adapt Vero cells to become serum-free adherent and, eventually, suspension cells. The resulting cell line will be fully safety-tested for human use, be able to grow in chemically defined media as a suspension culture, be able to be scaled up in single-use, stirred bioreactors for commercial production, include a platform purification process for each type of virus, be well characterized, and go through process characterization and validation. The cells will be used with multiple virus platforms, whether the product is produced by infection (a virus infecting the Vero cells) or transfection (DNA plasmids). Phase 2 will see the development of high–cell-density cultures with high yields per cell. FDB has completed licensing of the Vero cells, and clean cells have been brought into the facility.

Three proof-of-concept studies have been conducted: “Ad5 Yields from Adherent Parental Vero Compared to HEK 293 with Serum,” “Comparison of Ad5 Yields from SF-Vero Adherent to Parental,” and “Comparison of Ad5 Yields from SF-Vero Suspension to Parental.” FDB found no change in viral productivity after adaptation. Company scientists also found that cells were 75% viable at harvest, and yield could be optimized by increasing the fermentation time.

FDB offers process development through commercial manufacturing services with multiple options to suit its customers. The cell lines will be fully tested and growthoptimized to prevent delays in starting projects. Upstream and downstream processes will be platformed for each virus, and there will be no licensing fees for use of this system if customers stay with FDB for manufacturing. The license for Vero cells is complete, and different Vero cell lines now are being studied. That will continue through 2019 so the adherent cells will be ready for GMP production in 2019, and suspension-adapted cells will be ready in 2020.

Challenges in Viral Vaccine, Cell, and Gene Therapy Production
First-in-human trials (developing the process with limited knowledge, dose required might be unknown)
Success metrics unknown (assays to measure success not yet developed)
Components of the treatment are difficult to buy or make (components of the process are rare and exist in very small quantities)
Difficult to scale up (current manufacturing process is not amenable to scale up)

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