Absence of Replication-Competent Lentivirus in the Clinic: Analysis of Infused T Cell Products

• Published in: Molecular therapy Vol. 26; no. 1; pp. 280 - 288
• Main Authors: Cornetta, Kenneth, Duffy, Lisa, Turtle, Cameron J., Jensen, Michael, Forman, Stephen, Binder-Scholl, Gwendolyn, Fry, Terry, Chew, Anne, Maloney, David G., June, Carl H.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 03.01.2018; Elsevier Limited; American Society of Gene & Cell Therapy
• Subjects: Cancer; Cancer immunotherapy; clinical gene therapy; Clinical trials; Deoxyribonucleic acid; DNA; Gene therapy; Immunotherapy; lentivirus; Leukemia; Lymphocytes; Lymphocytes T; Original; Replication; replication-competent virus; safety; T cell receptors; Transfection; Vectors (Biology); Viruses; United States > US; clinical gene therapy; safety; immunotherapy; lentivirus; replication-competent virus
• ISSN: 1525-0016; 1525-0024; 1525-0024
• DOI: 10.1016/j.ymthe.2017.09.008

Exposure to replication-competent lentivirus (RCL) is a theoretical safety concern for individuals treated with lentiviral gene therapy. For certain ex vivo gene therapy applications, including cancer immunotherapy trials, RCL detection assays are used to screen the vector product as well as the vector-transduced cells. In this study, we reviewed T cell products screened for RCL using methodology developed in the National Gene Vector Biorepository. All trials utilized third-generation lentiviral vectors produced by transient transfection. Samples from 26 clinical trials totaling 460 transduced cell products from 375 subjects were evaluated. All cell products were negative for RCL. A total of 296 of the clinical trial participants were screened for RCL at least 1 month after infusion of the cell product. No research subject has shown evidence of RCL infection. These findings provide further evidence attesting to the safety of third-generation lentiviral vectors and that testing T cell products for RCL does not provide added value to screening the lentiviral vector product. The safety of lentiviral vectors is a factor in their acceptance as clinical therapies. In this issue of Molecular Therapy, Cornetta et al. (2017) screened 460 cell products for replication-competent lentivirus (RCL); none were positive. The low risk of RCL suggests that revisions to U.S. FDA testing guidelines are warranted.