Clinical Grade Vector Production: Analysis of Yield, Stability, and Storage of GMP-Produced Retroviral Vectors for Gene Therapy

Retroviral vector gene transfer of a therapeutic gene to correct or modify a disease process is a promising strategy for many inherited and acquired diseases. A major obstacle in this process is the large-scale production of the gene transfer vector under good manufacturing practice (GMP) conditions. We have used the CellCube bioreactor system to produce five batches of GMP-grade vector. The production batches were of 10-20 L each, and the titers were around 2 × 10^6 IU/mL. We find that this particular vector is relatively stable with a half-life of about 8 h at 37 °C, 40 h at 20 °C, and 14 days at 4 °C. The half-life during storage at -80 °C is around 18 months. The supernatant may be frozen and thawed up to five times without any significant loss of titer. We have also made a comparison between the CellCube bioreactor and the automated roller bottle system RollerCell 40 (RC 40). The yields from the two systems were comparable.