Browsing by Author "Yao, Jing"

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    Real-Time PCR: An Effective Tool for Measuring Transduction Efficiency in Human Hematopoietic Progenitor Cells
    (Elsevier, 2004-12-04) Villella, Anthony D.; Yao, Jing; Getty, Robert R.; Juliar, Beth E.; Yiannoutsos, Constantin; Hartwell, Jennifer R.; Cai, Shanbao; Sadat, Mohammed A.; Cornetta, Kenneth; Williams, David A.; Pollok, Karen E.; Medical and Molecular Genetics, School of Medicine
    Accurate measurement of gene transfer into hematopoietic progenitor cells is an essential prerequisite for assessing the utility of gene therapy approaches designed to correct hematologic defects. We developed a reliable method to measure transduction efficiency at the level of the progenitor cell with real-time polymerase chain reaction (PCR) analysis of individual progenitor-derived colonies. We hypothesized that this method would demonstrate better sensitivity and specificity than are currently achievable with conventional PCR. An oncoretroviral vector containing the enhanced green fluorescent protein was used to transduce human CD34+ cells derived from bone marrow or granulocyte-colony-stimulating factor-mobilized peripheral blood. Progenitor assays were set up and colonies plucked after visualization by fluorescence microscopy. By analyzing microscopically identified fluorescent samples and nontransduced samples, we calculated an overall sensitivity and specificity of 90.2 and 95.0%, respectively. Real-time PCR had higher specificity and sensitivity than conventional PCR as analyzed by generalized linear models (P = 0.002 and P = 0.019, respectively). In conclusion, we found real-time PCR to have superior sensitivity and specificity compared to conventional PCR in determining transduction efficiency of hematopoietic progenitor cells.
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    Replication competent retrovirus testing (RCR) in the National Gene Vector Biorepository: No evidence of RCR in 1,595 post-treatment peripheral blood samples obtained from 60 clinical trials
    (Elsevier, 2023) Cornetta, Kenneth; Yao, Jing; House, Kimberley; Duffy, Lisa; Adusumilli, Prasad S.; Beyer, Rachel; Booth, Claire; Brenner, Malcolm; Curran, Kevin; Grilley, Bambi; Heslop, Helen; Hinrichs, Christian S.; Kaplan, Rosandra N.; Kiem, Hans-Peter; Kochenderfer, James; Kohn, Donald B.; Mailankody, Sham; Norberg, Scott M.; O’Cearbhaill, Roisin E.; Pappas, Jennifer; Park, Jae; Ramos, Carlos; Ribas, Antonio; Rivière, Isabelle; Rosenberg, Steven A.; Sauter, Craig; Shah, Nirali N.; Slovin, Susan F.; Thrasher, Adrian; Williams, David A.; Lin, Tsai-Yu; Medical and Molecular Genetics, School of Medicine
    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.