460. MGMTP140K Vector Constructs for Efficient In Vivo Enrichment of Genetically Corrected Cells Following Hematopoietic Cell Gene Transfer

MGMTP140K, a mutant of the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) resistant to the inhibitor O6-benzylguanine (BG), protects hematopoietic stem cells (HSC) from the toxicity of alkylating agents such as temozolomide (TMZ) and, therefore, allows efficient in vivo enrichment of transduced cells by BG/TMZ therapy. MGMTP140K has been proposed as a selection marker in gene therapy of monogeneic diseases. If used for this purpose, however, MGMTP140K expression in vectors containing internal ribosomal entry sites (IRES) would be from the compromised 3' position, as the 5' position will be required for the therapeutic gene. Thus, we have investigated SFFV/MESV-based vector…