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Updated: Aug 17, 2025
Production of Replication-Defective Retrovirus by Transient Transfection of 293T cells
Published on: December 4, 2007
Replication competent retrovirus testing (RCR) in the National Gene Vector Biorepository: No evidence of RCR in 1,595
Kenneth Cornetta1, Jing Yao2, Kimberley House2
1Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA; Brown Center for Immunotherapy, Indiana University School of Medicine, Indianapolis, IN, USA.
Abstract:
The clinical impact of any therapy requires the product be safe and effective. Gammaretroviral vectors pose several unique risks, including inadvertent exposure to replication competent retrovirus (RCR) that can arise during vector manufacture. The US FDA has required patient monitoring for RCR, and the National Gene Vector Biorepository is an NIH resource that has assisted eligible investigators in meeting this requirement. To date, we have found no evidence of RCR in 338 pre-treatment and 1,595 post-treatment blood samples from 737 patients associated with 60 clinical trials. Most samples (75%) were obtained within 1 year of treatment, and samples as far out as 9 years after treatment were analyzed. The majority of trials (93%) were cancer immunotherapy, and 90% of the trials used vector products produced with the PG13 packaging cell line. The data presented here provide further evidence that current manufacturing methods generate RCR-free products and support the overall safety profile of retroviral gene therapy.
