Systematic Comparison Of The Ef-1 Alpha Short (Efs) And Viral Promoters For Gene Modification Of Human Primary Cells For Clinical Applications

Optimization of transgene expression is paramount for successful gene modification of primary cells for clinical applications, and careful selection of the viral vector construct is a critical part of this process. Viral promoters based on the U3 region of the Moloney murine leukemia virus (such as MNDU3 and MSCV) are currently the most commonly used for gene transfer in human primary cells. These viral promoter-containing vectors, however, can activate nearby genes, potentially causing toxicity and/or neoplastic transformation. EF1alpha (or its short, intron-less form, EFS) is a promoter that has been recently used in many clinical trials. It is a cellular-derived enhancer/promoter with decreased cross-activation of nearby promoters, therefore hypothetically decreasing the risk of genotoxicity. We have produced vector constructs carrying the internal enhancer/promoters MNDU3, MSCV, or EFS driving clinically relevant transgenes for modification of primary human T lymphocytes and hematopoietic stem cells.